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Bibliography « Sand and Dust occurrence » Dust Sources and atmospheric dust process authors title contents publication R. Arimoto Y.J. Kim Y.P. Kim P.K. Quinn T.S. Bates T.L. Anderson S. Gong I. Uno M. Chin B.J. Huebert A.D. Clarke Y. Shinozuka R.J. Weber J.R. Anderson S.A. Guazzotti R.C. Sullivan D.A. Sodeman K.A. Prather I.N. Sokolik

Characterization of Asian Dust during ACE-Asia

- dust has a pervasive influence on the chemical composition, size distribution, and optical properties of the aerosol - most of the coarse-particle nitrate and sulfate in post-frontal air was associated with dust - studies showed that coarse-mode dust was less absorbing and less hygroscopic than pollution aerosol + little correlation in light scattering and absorption by the sub- vs. super-micrometer aerosol - below ∼2 km, dust was commonly mixed with pollutants → stronger influence on the optical properties of the submicrometer particles than the coarse-mode dust - mixing of black carbon (BC) with dust was common, but only certain types of BC particles were aggregated

Global and Planetary Change 52, p.23–56; 2006

S.R. Aston R. Chester L.R. Johnson R.C. Padgham

Eolian dust from the lower atmosphere of the eastern Atlantic and Indian Oceans, China Sea and Sea of Japan

- average dust-loadings in the lower atmosphere: North Atlantic (northeast trades, 7.7 μg/m3 of air) > northern Indian Ocean (1.2 μg/m3 of air) > South Atlantic (southeast trades, 0.78 μg/m3 of air) = southern Indian Ocean (0.68 μg/m3 of air) > China Sea (0.21 μg/m3 of air) - dusts in the Atlantic northeast trades are dominated by kaolinite from the soils of equatorial Africa; dusts in the northeast monsoons of the northern Indian Ocean have a source in the arid regions of the Rajasthan desert where illite is the principal clay mineral - quartz occurs in larger amounts in the dusts of the Northern Hemisphere (7%) than those of the Southern Hemisphere (3%) over the Atlantic and Indian Oceans - map

Marine Geology 14, Issue 1, p. 15-28; 1973

R. Bagnold The Physics of Blown Sand and Desert Dunes

Proceedings of the Royal Society A 225 49; 1954

I. Chiapello G. Bergametti B. Chatenet P. Bousquet

Origins of African dust transported over the northeastern tropical Atlantic

- measurements of mineral dust concentrations at Sal Island (Cape Verde) during the dusty season (October to April) - three different sectors of origin of the transported dust: Sahara (north/west and central/south) and the Sahel regions

Journal of Geophysical Research 102(D12), p. 13,701-13,709; 1997 doi:10.1029/97JD00259

F. Dulac E. Santos Soares

- time variations of the dust transport can be explained by the seasonal shift of the subtropical high-pressure center

T. Claquin M. Schulz Y. Balkanski

Modeling the mineralogy of atmospheric dust sources

Journal of Geophysical Research 104(22), p. 243-256; 1999

S. Engelstaedter K.E. Kohfeld I. Tegen S.P. Harrison

Controls of dust emissions by vegetation and topographic depressions: An evaluation using dust storm frequency data

- examination of dust storm frequency (DSF) derived from visibility records to evaluate the controls of dust emissions by vegetation cover and geomorphic setting - DSF is highest in desert/bare ground (median: 60–80 d/yr) and shrubland (median: 20–30 d/yr) regions, and comparatively low in grassland regions (median: 2–4 d/yr) - DSF is inversely correlated with leaf area index (index of vegetation density) and net primary productivity → significant variability in emissions within vegetation types

Geophysical Research Letters 30(6); 2003 doi:10.1029/2002GL016471

L. Gomes G. Bergametti G. Coudé-Gaussen P. Rognon

Submicron desert dusts: A sandblasting process

- description of aerosol production due to sandblasting Journal of Geophysical Research 95(13), p. 927–13; 1990

A.S. Goudie N.J. Middleton

Desert Dust in the Global System

- the Nature and Importance of Dust Storms - Dust Entrainment, Transport and Deposition (Origin of Desert Dust Particles, Threshold Velocities, Wind Erosion, Long-Range Transport, Wet and Dry Deposition…) - Environmental and Human Consequences (Marine Ecosystems, Erosion and Contamination of Soils, Desert Depressions, Radiative Forcing, Chemistry interactions (CO2, Ozone), Clouds, Health, …) - Global scale (Rainfall, Vegetation, Diurnal and Seasonal Timing of Dust Storms) - Regional Scale (North America, South America, Southern Africa, Sahara, Middle East, South West Asia, Central Asia and the Former USSR, China, Mongolia, Australia) - Dust Concentrations, Accumulation and Constituents - Dust Storm Control - Quaternary Dust Loadings - Loess

ISBN-10 3-540-32354-6 Springer

A. Grini C.S. Zender P. Colarco

Saltation sandblasting behavior during mineral dust aerosol production

- description of aerosol production due to sandblasting Geophysical Research Letters 29(18), p. 1868; 2002

A. Kumar M.M. Sarin

Mineral aerosols from western India: Temporal variability of coarse and fine atmospheric dust and elemental characteristics

- PM2.5 and PM10 samples collected in India (Jan–Dec-2007) - dominant and uniform contribution of mineral dust (60–80%) in the coarse mode relative to large temporal variability (11–75%) observed in the fine mode - coarse mass fraction: characteristic increase with the wind speed during summer months (Mar to Jun - fine aerosol mass: temporal pattern associated with north-easterlies

Atmospheric Environment 43, p. 4005-4013; 2009 doi:10.1016/j.atmosenv.2009.05.014

during wintertime (Oct–Feb) - relative enrichment of Fe in fine mode Fe/Al weight ratio during winter months due to the down-wind advective transport of combustion products derived from large-scale biomass burning, industrial and automobile emission sources (northern India) - relative enrichment of Ca and Mg in the coarse mode Ca/Al and Mg/Al weight ratios shows dominant contribution from carbonate minerals

J.M. Prospero P. Ginoux O. Torres S.E. Nicholson T.E. Gill

Environmental characterization of global sources of atmospheric soil dust derived from the NIMBUS7 TOMS absorbing aerosol product, Rev

- TOMS sensor on the Nimbus 7 satellite was used to map the global distribution of major atmospheric dust sources - largest and most persistent sources: “dust belt” (Northern Hemisphere, from the west coast of North Africa, over the Middle East, Central and South Asia, to China) - Southern Hemisphere is devoid of major dust activity - dust sources can be associated with topographical lows located in arid regions with annual rainfall under 200–250 mm - many sources are associated with areas where human impacts are well documented

Geophysical Journal 40, p. 2002; 2002

J.M. Prospero R.T. Nees

Dust Concentration in the Atmosphere of the Equatorial North Atlantic: Possible Relationship to the Sahelian Drought

- increase of the concentration of insoluble mineral aerosol in the lower troposphere of the western equatorial North Atlantic Ocean by a factor of 3 over the last decade → may be related to the Sahelian drought

Science New Series 196(4295), p. 1196-1198; 1977

K. Psye H. Tsoar

Aeolian Sand and Sand Dunes - nature of airflow - characteristics of windblown sediments - mechanics of aeolian sand transport - …

ISBN: 978-3-540-85909-3 Springer 2009

Y. Shao M. Raupach

Effect of saltation bombardment by wind

- description of saltation process Journal of Geophysical Research 98(12), p. 719–12; 1993

M.C. Todd R. Washington J. Vanderlei Martins O. Dubovik G. Lizcano S. M’Bainayel S. Engelstaedter

Mineral dust emission from the Bodélé Depression, northern Chad, during BoDEx 2005

- the Bodélé Depression of northern Chad is the world’s greatest source region of mineral dust into the atmosphere → may be responsible for 6–18% of global dust emission - results from the BoDEx 2005 experiment are presented - the aerosol loading in this source region is highly variable from day to day - the large dust plume events during BoDEx 2005 were triggered by strong wind events driven by ridging of the Libyan high-pressure cell - specific threshold wind speed (15 min average at 2 m height) for dust emission to be 10.0 m s-1 is unusually high in comparison to other dust source regions - the dominant coarse mode of the particle size distribution of dust is characteristic of other Saharan dust observation despite the unusual characteristics of the Bodélé diatomite sediment (there is minor but noticeable presence of particles with radii < 1 mm) - the single-scattering albedo of Bodélé dust is very high with relatively

Journal of Geophysical Research 112, D06207; 2007 doi:10.1029/2006JD007170

low wavelength dependence - evidence of dust transport from the Bodélé up to distances of at least 1700 km, dust is transported highly likely much farther, as far as South America

C. Zender Natural Aerosols in the Climate System

- few chapters about dust aerosol, containing among others: - Dust Source Processes - Boundary Layer Physics - Wind Stress/Wind Speed - Stability - Threshold Wind Friction Speed - Surface Fluxes/Dust Fluxes - Dust Devils - Dependence On Soil Moisture -Geomorphology - Dust Source Regions (Bodélé Depression, Takla Makan Desert, Lake Eyre Basin…) - Dry Deposition - Wet Deposition - Precipitation-Aerosol Interactions - Radiative Properties - Heterogeneous Chemistry - Chemistry and Mineral Dust - Biogeochemistry (Nutrients…)

Onlinebook http://dust.ess.uci.edu/facts 2008

Dust transport and deposition authors title contents publication D. Balis V. Amiridis S. Kazadzis A. Papayannis G. Tsaknakis S. Tzortzakis N. Kalivitis M. Vrekoussis M. Kanakidou N. Mihalopoulos G. Chourdakis S. Nickovic C. Pérez J. Baldasano M. Drakakis

Optical characteristics of desert dust over the East Mediterranean during summer: a case study

- the spatial and temporal evolution of a Saharan dust outbreak during 30–31 August 2003 has been studied in detail using coordinated measurements by three lidar systems over Greece located at Thessaloniki, Athens and Finokalia, Crete - many high AOD events corresponding to Saharan dust - mixing of dust with aerosol from other sources commonly occurs over Greece and impedes the separation of dust in the aerosol profiles which are extremely case sensitive, showing that the case could imply large uncertainties if it is treated in a statistical way → multiwavelength lidar and sunphotometric measurements are essential for the calculation of the microphysical aerosol properties in the vertical

Annales Geophysicae 24, p. 807–821; 2006

Y. Chung On the observations of yellow sand (dust storms) in Korea

- outbreak of dust storms (yellow sand) from Northern China and Mongolia occurs a few time in spring

Atmospheric Environment 26 A, Issue 15, p. 2743-2749; 1992

- dust cloud can move to Korea and Japan in 2–4 days - phenomenon occurs in the lee sides of massive mountains; the Tienshan-Altai-Sayan Mts ↔ downslopes barriers are favourable regions of föhn (dry air) and of orographic cyclogenesis - in Korea the episodes of yellow sand appear to occur after the passage of a dry cold front of a cyclone - with the invasion of dust clouds, visibility less than 1 km has been observed and atmospheric loadings up to 1105 μg m−3

S. Engelstaedter I. Tegen R. Washington

North African dust emissions and transport

- intense source regions (Bodélé Depression and the West African sources in the heat low region of the Sahara) have been recognized - Models have led to estimates of the sensitivity of the radiation budget to changes in dust properties - largest dust emitting region in the world: North Africa - Africa: efficient transport mechanisms - the combination of sources rich in deflatable material and energetic wind systems, that facilitate long range transport make it possible to influence remote ecosystems

Earth Science Reviews 79, Issues 1-2, p. 73-100; 2006

A.T. Evan A.K. Heidinger P. Knippertz

Analysis of winter dust activity off the coast of West Africa using a new 24-year over-water advanced very high resolution radiometer satellite dust climatology

- strong relationship between tropical North Atlantic dustiness and this vegetation index → possibility that vegetation changes in the Sahel play an important role in variability of downwind dustiness - a climatological study showed a distinct region of enhanced mean dust values over the tropical North Atlantic and another over the Gulf of Guinea - the correlations between the Sahel NDVI and dust coverage in the TATL region could be interpreted as signifying that vegetation in the Sahel exerts a certain amount of control on the dust in the downwind areas, considering the predominant trade flow - but: it is possible that these correlations result from general circulation features that alter summertime Sahel precipitation as well as dustiness independent of vegetation influences


S. Fan L.W. Horowitz H. Levy II W.J. Moxim

Impact of air pollution on wet deposition of mineral dust aerosols

- air pollution increases the scavenging of dust by producing high levels of readily soluble materials on the dust surface, which makes dust aerosols effective cloud condensation nuclei (CCN) → air pollution could have caused an increase of dust deposition to the coastal oceans of East Asia and a decrease by as much as 50% in the eastern North Pacific

Geophysical Research Letters 31, L02104; 2004 doi:10.1029/2003GL018501

S. Fan W.J. Moxim H. Levy II

Implications of droplet nucleation to mineral dust aerosol deposition and transport

- activation threshold radius (ATR) for droplet nucleation is typically found in the range of clay-sized particles (0.1 to 1.0 mm), a spectrum over which the amount of dust removed declines ~60% both in surface area and particle number; nucleation of silt-sized particles occurs under most conditions - larger fractions of mineral aerosols are removed in cumulus clouds than in stratus - acid coating of dust particles in polluted environments acts to decrease the ATR (reduced by competition with soluble aerosols) - regional mineral dust environments exhibit potentially diverse aerosol


wet removal impacts S. Gassó A.F. Stein

Does dust from Patagonia reach the sub-Antarctic Atlantic Ocean?

- difficult to determine Patagonian dust by satellite measurements (clear sky condition needed, no black background (sea-ice), dust emission short lived) → combined approach of different satellite detectors aided by an aerosol transport model - observations confirm that dust advects through the SW Atlantic Ocean and can reach the area around the biological rich sub-Antarctic Ocean within 30 hours of emission


D.W. Griffin C.A. Kellogg E.A. Shinn

Dust in the Wind: Long Range Transport of Dust in the Atmosphere and Its Implications for Global Public and Ecosystem Health

- benefits and the potential hazards associated with exposure to particle fallout as clouds of desert dust traverse the globe

Global Change & Human Health 2(1), p. 20-33; 2001 doi: 10.1023/A:1011910224374

P.L. Israelevich Z. Levin J. H. Joseph E. Ganor

Desert aerosol transport in the Mediterranean region as inferred from the TOMS aerosol index

- identifying of dust sources by investigating local maxima of the TOMS aerosol index distribution - spring-summer: flux of dust from the sources at lat ∼16°N/long ∼16°E (Chat basin, maximum activity April) and lat ∼19°N/long ∼6°W (more variable, maximum July) → the atmosphere over North Africa is almost permanently loaded with a significant amount of mineral dust - Sharav cyclones (low pressure systems) mobilize the already suspended mineral dust and transport it eastward and northward along the Mediterranean basin

Journal of Geophysical Research 107(D21), p. 4572; 2002

C. Moulin C.E. Lambert U. Dayan V. Masson M. Ramonet P. Bousquet M. Legrand Y.J. Balkanski W. Guelle B. Marticorena G. Bergametti F. Dulac

Satellite climatology of African dust transport in the Mediterranean atmosphere

- despite a large daily variability, climatological results show a clear seasonal cycle with a maximum during the dry season - dust transport begins over the eastern basin in spring and spreads over the western basin in summer → related to cyclogenesis over North Africa and rainfall over the Mediterranean Sea - frequency of dust mobilization over the continent and of dust outbreaks over the sea are strongly related to the climatology of depressions affecting North Africa - precipitations appear to be an important factor explaining the seasonal east-west shift in transport location and the south-north gradients of dust concentrations over the Mediterranean


C. Pérez S. Nickovic J.M. Baldasano M. Sicard F. Rocadenbosch V.E. Cachorro

A long Saharan dust event over the western Mediterranean: Lidar, Sun photometer observations, and regional dust modeling

- the western Mediterranean is affected by Saharan dust events mostly in spring and summer → long Saharan dust event 12–28 June 2002 - was followed by a EARLINET lidar device in Barcelona and two AERONET Sun photometers located at Spain and France → spatial and temporal evolution, optical properties and vertical structure of the dust plume were analyzed in detail together with DREAM - dust was present mainly between 1- and 5-km height - sequences of 3 main meteorological low index circulation patterns (high pressure over the western Mediterranean, high pressure over


northwestern Africa and low pressure over southwestern Portugal) explained the persistence of dust over the region for more than 2 weeks - anthropogenic aerosols contribute significantly to the observed aerosol optical properties → discrepancy model and measurements - lidars: ability to assess dust structure and optical properties with high vertical resolution

K.D. Perry T.A. Cahill R.A. Eldred D.D. Dutcher T.E. Gill

Longrange transport of North African dust to the eastern United States

- North African dust incursions into the continental United States persist for ∼10 days and occurred, on average, 3 times per year from 1992 to 1995 - fine soil mass usually exceeds 10 μg m−3 during these dust episodes and dominates local fine soil dust by an order of magnitude or more - mass mean diameter of the transported North African dust is < 1 μm → high mass scattering efficiency and abundant particle surface area → radiative balance of the region and the chemistry of the local aerosols


J.M. Prospero

Long-range transport of mineral dust in the global atmosphere: Impact of African dust on the environment of the southeastern United States

- Dust transported over long distances usually has a mass median diameter <10 μm - Small wind-borne soil particles show signs of extensive weathering; consequently, the physical and chemical properties of the particles will greatly depend on the weathering history in the source region and on the subsequent modifications that occur during transit in the atmosphere (typically a period of a week or more) - particles with diameters of a few micrometers or less will have a relatively long lifetime in the atmosphere with respect to gravitational settling—in the absence of precipitation removal, on the order of several weeks → can be transported thousands of kilometers by winds

Proceedings of the National Academy of Sciences 96(7), p. 3396-3403; 1999

J.M. Prospero E. Bonatti

Continental Dust in the Atmosphere of the Eastern Equatorial Pacific

- dust samples in the area of 8°N to 17°S and 80°W to 110°W (spring 1967): dust loads from 0.04 to 1.2 μg/m3, highest concentrations along a track between 5° and 8°N - mineralogical composition of the samples collected north of the equator differs from the more southerly samples → northern dust: plagioclase dominant mineral and subordinate amounts of quartz southern dust: quartz prevalent, appreciable quantities of micas, chlorites, and smectites - all samples contain organic material

Journal of Geophysical Research 74(13), p. 3362-3371; 1969 doi:10.1029/JC074i013p03362

J.M. Prospero

E. Bonatti C. Schubert T.N. Carlson

Dust in the Caribbean atmosphere traced to an African dust storm

- satellite observation and investigation of the composition of the dust at Barbados after a dust event in the Sahara → most of the airborne dust transported over the western Atlantic Ocean during the summer and early fall is derived from the same general area of the storm — Spanish Sahara, Mauritania, Mali and Senegal

Earth and Planetary Science Letters 9, Issue 3, p. 287-293; 1970

T. Takemura I. Uno T. Nakajima A. Higurashi

Modeling study of long-range transport of Asian dust and anthropogenic aerosols from East Asia

- three-dimensional aerosol transport-radiation model: SPRINTARS - 10 to 20% of the Asian dust around Japan reached North America - the contribution of the anthropogenic aerosol (carbonaceous, sulfate aerosol emitted from the industrialized areas) to the total optical thickness is simulated to be of a comparable order to that of the Asian

Geophysical Research Letters 29, p. 2158; 2002 doi:10.1029/2002GL016251

I. Sano dust O.B. Toon J.B. Pollack T.P. Ackermann R.P. Turco C.P. McKay M.S. Liu

Evolution of an impact-generated dust cloud and its effects on the atmosphere

- simulation of the evolution of an optically thick dust cloud: large quantities of dust remain in the atmosphere for periods of only three to six months ↔ coagulation → sedimentation - duration of the event is nearly independent of the initial altitude, initial particle size, initial mass, atmospheric vertical diffusive mixing rate, and rainout rate / is dependent on the particle density and the colliding probability → limited by the rate at which the debris spreads from the initial impact site

Geological implications of impacts of large asteroids and comets on the earth (A84-25651 10-42) Geological Society of America, p. 187-200; 1982

R.A. VanCuren T. A. Cahill

Asian aerosols in North America: Frequency and concentration of fine dust

- fine (<2.5 μm) Asian dust is a regular component of the troposphere over the eastern Pacific and western North America and is common, at least in spring, across North America (consistent with isentropic transport processes previously observed in the western Pacific) - the annual dust minimum occurs during winter, with potential implications for the natural efficiency of winter precipitation and the formation of supercooled drizzle

Journal of Geophysical Research 107; 2002 doi:10.1029/2002JD002204

R. Vautarda B. Bessagnetb M. Chinc L. Menutd

On the contribution of natural Aeolian sources to particulate matter concentrations in Europe: Testing hypotheses with a modeling approach

- considering only European anthropogenic emissions, chemistry-transport model simulations underestimate the PM10 concentrations by 30–50% → missing mass originates from natural sources like erosion dust entrainment and resuspension of material available on the ground

Atmospheric Environment 39, p. 3291–3303; 2005 doi:10.1016/j.atmosenv.2005.01.051

Anthropogenic impact on dust occurrence authors title contents publication N.M. Mahowald C. Luo

A less dusty future? - Atmospheric desert dust is potentially highly sensitive to changes in climate, carbon dioxide and human land use. - simulations suggest increases of 24% or decreases of 63% in atmospheric loading between the pre-industrial climate relative to today - high sensitivity of ‘natural aerosols’ to human intervention: anthropogenic portion of current desert dust can be between 14 to 60%. Humans and climate change have caused a 9 to 24% decrease in mineral aerosols since pre-industrial times, depending on which scenario is most realistic

Geophysical Research Letters 30(17); 2003 doi:10.1029/2003GL017880

I. Tegen I. Fung

Contribution to the atmospheric mineral aerosol load from land surface modification

- contribution of mineral dust from disturbed soils (i.e., soils affected by human activity and/or climate variability) to the total atmospheric mineral aerosol load is presented → observed features like the seasonal shift of maximum optical thickness caused by Saharan dust over the Atlantic ocean are best reproduced if disturbed sources contribute 30–50% of the total atmospheric dust loading


I. Tegen M. Werner S.P. Harrison K.E. Kohfeld

Relative importance of climate and land use in determining present and future global soil dust emission

- dust from agricultural soils contributes less than 10% to global dust emissions under modern climate conditions → even if significant locally, is not of great importance for the global radiation budget today - agricultural regions are not the only source of anthropogenic dust → possible changes in sources through deforestation


C. M. Taylor E.F. Lambin N. Stephenne R.J. Harding R.L.H. Essery

The Influence of Land Use Change on Climate in the Sahel

- changes in vegetation in the Sahel can cause substantial reductions in rainfall ↔ extent and intensity of vegetation changes are crucial in determining the magnitude of the atmospheric response in the models - one important driver of vegetation change is land use practice → in this paper the hypothesis that recent changes in land use have been large enough to cause the observed drought is tested - suggestion: Sahel cropland coverage has risen from 5% to 14% in the 35 yr prior to 1996 (4% of the land from tree cover to bare soil) - the model predicts further changes in the composition of the land surface by 2015 based on changes in human population, livestock population, rainfall, cereals imports, and farming systems - relative to 1961 simulated rainfall decreases by 4.6% (1996) and 8.7% (2015) → later onset of the wet season core during July - once the wet season is well developed the sensitivity of total rainfall to the land surface is greatly reduced, and depends on the sensitivity of synoptic disturbances to the land surface - climate of the region is rather sensitive to small changes in albedo and leaf area index, recent historical land use changes are not large enough to have been the principal cause of the Sahel drought, but climatic impacts of land use change in the region are likely to increase rapidly in the coming years

Journal of Climate 15, p. 3615–3629; 2002

X. Wang Z. Zhou Z. Dong

Control of dust emissions by geomorphic conditions, wind environments and land use in northern China: An examination based on dust storm frequency from 1960 to 2003

- investigation used the dust storm frequency (DSF) and meteorological data - most dust emissions originated in gobi deserts that developed in piedmont alluvial fans of the Kunlun, Qilian and Helan mountains - Dust emissions are low where high vegetation coverage restrained dust emissions or where dust-size particles are not abundant after a long period of strong wind erosion → Sandy deserts with relatively high vegetation coverage or an extensive cover by mobile sands are not a major dust source - DSF trends were closely related to local wind activity - DSF was low in regions with high levels of human activity, which indicates that extensive land use did not contribute to DSF ↔ although land use could produce abundant fine soil fractions, vegetation coverage and soil moisture remained higher than in the gobi deserts of arid China

Geomorphology 81, Issues 3-4, p. 292 -308; 2006

J. Xu Sand-dust storms in and around the Ordos Plateau of China as influenced by land use change and desertification

- the occurrence of sand-dust storms induced by wind erosion is a process that accelerates land degradation and can also be considered as an indicator of desertification - non-linear relationship between sand-dust storm frequency and the index of land degradation (Id, percentage of the area of total land that is desertified) - threshold at Id = 30%, when Id < 30% sand-dust storm frequency does not change with increasing Id, but when Id > 30%, sand-dust storm frequency increases rapidly → sand-dust storm frequency would increase abruptly when the human-induced Id exceeds 30%

Catena 65, Issue 3, p. 279-284; 2006

Measurement techniques authors title contents publication D.S. Balis V. Amiridis S. Nickovic A. Papayannis C. Zerefos

Optical properties of Saharan dust layers as detected by a Raman lidar at Thessaloniki, Greece

- the south-eastern Mediterranean is a crossroad where aerosol can be transported from very different sources - lidar measurements and DREAM - anticorrelation was found between the lidar ratio and the color index during the Saharan dust events - large lidar ratios of 80 sr correspond to the larger and also absorbing dust particles and are consistent with calculations that consider non-spherical particles - lidar ratios between 45 and 55 sr were found in most of the cases


R. Fraser Satellite measurement of mass of Sahara dust in the atmosphere

- measurements were made from the Landsat-1 satellite → resulting mass of particulates smaller than 10-µm radius in a vertical column is 1.6 g m-2

Applied Optics 15, Issue 10, p. 2471-2479; 1976 doi:10.1364/AO.15.002471

Y.J. Kaufman

D. Tanré

O. Boucher

Review article: A satellite view of aerosols in the climate system

- to study aerosol distribution and composition continuous observations from satellites, networks of ground-based instruments and dedicated field experiments is required → this review gives an overview about satellite measurements

Nature 419, p. 215-223; 2002 doi:10.1038/nature01091

M.E. Koukouli D.S. Balis V. Amiridis S. Kazadzis A. Bais S. Nickovic O. Torres

Aerosol variability over Thessaloniki using ground based remote sensing observations and the TOMS aerosol index

- TOMS = Total Ozone Mapping Spectrometer - - on board of TOMS: the Earth Probe satellite aerosol index (AI) version 8.0 - > indicator of the presence of absorbing aerosols in the atmosphere - measured AOD was compared with Brewer spectroradiometer in Thessaloniki (1997-2001) - 223 biomass burning events showed a correlation of 0.67 between the AOD and AI values whereas a correlation of 0.57 was deduced for the 37 cases of Saharan dust loading (biomass burning AOD: 0.3870.23 and 0.9770.77 (AI), Saharan dust AOD: 0.4270.19 and 1.2570.72 (AI)) - highest values were seen for trajectories that transport air from the Saharan desert and those that bring polluted air from Eastern Europe and the Balkan regions - the air above Thessaloniki in particular and Northern Greece in general contains a mixture of urban, continental, marine and dust aerosols → simple consideration of the AI and the AOD is not sufficient to provide positive insight

Atmospheric Environment, p. 1352-2310; 2006 doi:10.1016/j.atmosenv.2006.04.046

D. Nicolae C.P. Christescu

Laser remote sensing of tropospheric aerosol

- the accuracy of obtained information is dependent of technical performances of the device and of sensibility of data processing method → the quantitative results must be carefully analyzed and data validation (using e.g. satellite data) must be done - without any complementary data, no aerosol microphysical parameter can be derived from elastic backscatter Lidar data

Journal of Optoelectronics and advanced materials 8(5), p. 1781-1795; 2006

A. Papayannis V. Amiridis

Systematic lidar observations of Saharan dust over Europe

- more than 130 observation days of the horizontal and vertical extent of Saharan dust intrusions over Europe during the period May 2000 to December 2002

Journal of Geophysical Research 113, D10204; 2008

L. Mona G. Tsaknakis D. Balis J. Bösenberg A. Chaikovski F. De Tomasi I. Grigorov I. Mattis V. Mitev D. Müller S. Nickovic C. Pérez A. Pietruczuk G. Pisani F. Ravetta V. Rizi M. Sicard T. Trickl M. Wiegner M. Gerding R.E. Mamouri G. D’Amico G. Pappalardo

in the frame of EARLINET (2000–2002)

by coordinated lidar network in the frame of the European Aerosol Research Lidar Network (EARLINET) - number of dust events was greatest in late spring, summer, and early autumn periods, mainly in southern (S) and southeastern (SE) Europe - the center of mass of these layers was located in altitudes between 850 and 8000 m - mean thickness of the dust layer typically stayed around 1500–3400 m (mean center of mass from 2500 to 6000 m) - Southern European stations presented higher variability of the LR values and the backscatter-related Angström exponent values (BRAE) (LR: 20–100 sr; BRAE: _0.5 to 3) than northern ones (LR: 30–80 sr; BRAE: _0.5 to 1)

doi:10.1029/2007JD009028

A. Papayannis D. Balis V. Amiridis G. Chourdakis G. Tsaknakis C. Zerefos A.D.A. Castanho S. Nickovic S. Kazadzis J. Grabowski

Measurements of Saharan dust aerosols over the Eastern Mediterranean using elastic backscatter-Raman lidar, spectrophotometric and satellite observations in the frame of the EARLINET project

- lidar data analysis (2000–2002) to estimate the vertical extent of free tropospheric dust layers, as well as a seasonal distribution of Saharan dust outbreaks over Greece, under cloud-free conditions - mean value of the lidar ratio at 355 nm/AOT in the altitude range 0-5 km: Athens: 53±1 sr /0.69±0.12 Thessaloniki: 44±2 sr /0.65±0.10 during the Saharan dust outbreaks (within the dust layer the AOT was 0.23 and 0.21)

Atmospheric Chemistry and Physics 5, p. 2065–2079; 2005

G. Pappalardo J. Bösenberg A. Ansmann D. Balis C. Böckmann A. Chaikovsky A. Comeron R. Eixmann

Aerosol Lidar measurements in the framework of EARLINET

- EARLINET = European Aerosol Lidar Research Network - established in 2000 - consists of 22 lidar stations distributed in 12 European countries - observations are performed on a regular schedule: one daytime measurement per week around noon + two night time measurements per week (low background light) - quality assurance of data also includes the intercomparison of the retrieval algorithms for both backscatter and Raman lidar data - EARLINET observations have been supported by DREAM

2nd Symposium on Lidar Atmospheric Applications, Session 5. lidar networks and Autonomous systems (5.1); 2005

I.V. Grigorov A. Hågård V. Mitev S. Nickovic A. Papayannis J. Pelon M.R. Perrone D. Resendes V. Rizi V. Simeonov P. Sobolewski N. Spinelli T. Trickl G. Vaughan M. Wiegner M. Zavrtanik D. Tanré J. Haywood J. Pelon J.F. Léon B. Chatenet P. Formenti P. Francis P. Goloub E.J. Highwood G. Myhre

Measurement and modeling of the Saharan dust radiative impact: Overview of the Saharan Dust Experiment (SHADE)

Journal of Geophysical Research 108(D18), p. 8574; 2003 doi:10.1029/2002JD003273

Modeling authors title contents publication S.L. Gong X.Y. Zhang

CUACE/Dust – an integrated system of observation and modeling systems for operational dust forecasting in Asia

- CUACE/Dust (Chinese Unified Atmospheric Chemistry Environment for Dust) = integrated sand and dust storm (SDS) forecasting system - consists of a comprehensive dust aerosol module with emission, dry/wet depositions and other atmospheric dynamic processes, and a data assimilation system (DAS) using observational data from the CMA ground dust monitoring network and retrieved dust information from a Chinese geostationary satellite (FY-2C) - time series of the forecasted dust concentrations for a number of representative stations for the whole spring 2006 were evaluated against the surface PM10 monitoring data, showing a very good agreement in terms of the SDS timing and magnitudes near source regions where dust aerosols dominate


A. Grini G. Myhre C.S. Zender J.K. Sundet I.S.A. Isaksen

Model simulations of dust sources and transport in the global troposphere. Effects of soil erodibility and wind speed variability

- soil erodibility and wind speed variability influence the magnitude and geographical location of the dust emissions - emissions are highest in the areas where the erodibility is highest (strong variation with erodibility) - soil erodibility dataset of Zender et al. [2003] reproduces several typical aspects of the global dust cycle (high Chinese dust, high loading in Lake Chad area, higher emissions in Taklamakan than in Gobi), fails reproduce other aspects such as Lake Eyre being the dominant Australian source - dataset by Ginoux et al. [2001] gives high Somalian emissions, capture the main Saharan regions such as north eastern Sahara (Egypt/ Libya), western Sahara (Mali/Mauriania/ Algeria) and Lake Chad, but give low emissions in the Chinese deserts - maximum dust transport from Sahara to the Caribbean in the northern hemisphere summer, maximum dust production in Australia in the southern hemisphere summer and maximum dust production in the Chinese deserts in spring is reproduced by all model simulations - there is thought to be a connection between soil erodibility and soil reflectivity

Institute Report Series 124, Department of Geosciences, University of Oslo, ISBN 82-91885-26-5; 2003

G. Kallos A. Papadopoulos P. Katsafados S. Nickovic

Transatlantic Saharan dust transport: Model simulation and results

- an atmospheric model (SKIRON weather forecasting system) with incorporated dust uptake-transport-deposition module has been used to describe all the phases of the atmospheric dust lifecycle during long-range transport from the Sahara across the northern Atlantic


A. Mangold H. De Backer

Aerosol analysis and forecast in the European Centre

- the GEMS aerosol modeling system is novel as it is the first aerosol model fully coupled to a NWP model with data assimilation (three different events were chosen and are represented in the paper).


B. De Paepe S. Dewitte I. Chiapello Y. Derimian M. Kacenelenbogen J.F. Léon N. Huneeus M. Schulz D. Ceburnis C. O’Dowd H. Flentje S. Kinne A. Benedetti J.J. Morcrette O. Boucher

for MediumRange Weather Forecasts Integrated Forecast System: 3. Evaluation by means of case studies

- the study demonstrated the importance of combining model and observations for an accurate evaluation and monitoring of (anthropogenic) aerosol impacts

doi:10.1029/2010JD014864

J.-J. Morcrette O. Boucher L. Jones D. Salmond P. Bechtold A. Beljaars A. Benedetti A. Bonet J.W. Kaiser M. Razinger M. Schulz S. Serrar A.J. Simmons M. Sofiev M. Suttie A.M. Tompkins A. Untch

Aerosol analysis and forecast in the European Centre for Medium-Range Weather Forecasts Integrated Forecast System: Forward modeling

- forecast takes about twice as long as a forecast run without aerosols - http://gems.ecmwf. int/d/products/aer/realtime/ - ECMWF model can handle prognostic aerosols reasonably well, and be within the ‘‘accepted’’ diversity of the AEROCOM results


S. Nickovic G. Kallos A. Papadopoulos O. Kakaliagou

A model for prediction of desert dust cycle in the atmosphere

- Dust REgional Atmospheric Modelling (DREAM) - state of art parametrizations of all the major phases of the atmospheric dust life cicle such as production, diffusion, advection and removal - system is in operational use, providing 72hr forecasts for the Mediterranean region - uses dynamics of the Eta/NCEP model (based on large-scale numerical solutions controlled by conservation of integral properties, energetically consistent time-difference splitting, and the step-like mountain representation)

Journal of Geophysical Research 106(D16), p. 18,113-18,129; 2001

- dust production: based on viscous/turbulent mixing, shear-free convection diffusion, and soil moisture - dust sources are controlled by type of soil, type of vegetation cover, soil moisture content ans surface atmospheric turbulence - dust sinks: dry deposition (includes processes of deposition by surface turbulent diffusion and Brownian diffusion, gravitational settlement, and interception and impaction on the surface roughness elements), wet deposition (wet removal is calculated using the model precipitation water)

T. Niu S.L. Gong G.F. Zhu H.L. Liu X.Q. Hu C.H. Zhou Y.Q. Wang

Data assimilation of dust aerosol observations for the CUACE/dust forecasting system

- the data assimilation system for CUACE/Dust is based on a three dimensional variational method (3D-Var) and uses extensively the measurements of surface visibility (phenomena) and dust loading retrieval from the Chinese geostationary satellite (FY-2C) - it was found to provide corrections to both under- and over-estimates of SDS, presenting a major improvement to the forecasting capability of CUACE/Dust in the short-term variability in the spatial distribution and intensity of dust concentrations in both source regions and downwind areas - the seasonal mean Threat Score (TS) over the East Asia in spring 2006 increased from 0.22 to 0.31 by using the data assimilation system, a 41% enhancement


C. Pérez S. Nickovic G. Pejanovic J. Baldasano E. Özsoy

Interactive dust-radiation modeling: A step to improve weather forecasts

- the radiative effects of mineral dust have been fully incorporated into an atmospheric dust model → represents a promising approach for further improvements in numerical weather prediction practice and in radiative impact assessment over dust-affected areas - dust emission is modified by changes in friction velocity and turbulent exchange coefficients; dust turbulent mixing, transport and deposition are altered by changes in atmospheric stability, precipitation conditions and free atmosphere winds - strong dust negative feedback upon dust emission → smaller outgoing sensible turbulent heat flux → reduces the turbulent momentum transfer from the atmosphere and dust emission → area average of AOD over dustcovered regions is highly reduced


Y. Shao C.H. Dong

A review on East Asian dust storm climate, modelling and monitoring

- in arid and semi-arid area of Asia, dust storms occur frequently - Asian dust storms have a major impact on the air quality of the densely populated areas of China, Korea and Japan, and are important to the global dust cycle - Asian dust climatology is well documented in terms of dust storm frequency, distribution and seasonal variations. The synoptic systems for the generation of severe dust storms are well known - longterm variability of Asian dust is closely related to that of global circulation and an indicator of climate change

Global and Planetary Change 52, p. 1–22; 2006

- Dust emission varies greatly in space and time, depending on both atmospheric and land-surface conditions ↔ “point source” plumes which result in wide spread dust weather - problem: resolutions of atmospheric models are typically 10 to 100 km → too coarse to represent the spatial variations of dust emission - only limited dust-concentration data are available for model validation - dust concentration can be converted from visibility using empirical relationships, but the quality of the data is low because visibility depends not only on dust concentration, but also on particle size and atmospheric qualities such as air humidity and because visibility is a subjective measure

Y. Shao Y. Yang J. Wang Z. Song L.M. Leslie C. Dong Z. Zhang Z. Lin Y. Kanai S. Yabuki Y. Chun

Northeast Asian dust storms: Real-time numerical prediction and validation

- quantitative prediction of dust storms in real time by using an integrated wind erosion modeling system for 24-, 48-, and 72-hour forecasts of northeast Asian dust events for March and April 2002 - predictions are validated with 1. synoptic records, visibility from the meteorological network (1200 stations) 2. near-surface dust concentrations measured using lowvolume samplers at 12 locations in China, Japan and Korea - during a dust episode, dust sources and intensities vary in space and time, but on average the Gobi Desert, the Hexi Corridor, the Chaidam Basin, the Tulufan Basin, and the fringes of the Talimu and Zhunge’er Basins are identified to be the main source regions - Gobi Desert (central) has been found to be the strongest source of dust emission - the skill of the model decreases with forecast time, but even the 72-hour forecasts are still of high quality

Journal of Geophysical Research 108(D22), p. 4691; 2003 doi:10.1029/2003JD003667

I. Tegen I. Fung

Modeling of mineral dust in the atmosphere: Sources, transport, and optical thickness

- three dimensional model to study impact on the radiative balance of the atmosphere - characteristics of the model: - four size classes of mineral dust - transport is simulated with the tracer transport model of the Goddard Institute for Space Studies - dust source and sink parameterizations based on empirical data sets - no anthropogenic dust sources - realistic reproduction of data - relative increase of clay concentration above the height - indication that undisturbed desert areas are relatively weak sources of dust compared to areas influenced by human activity

Journal of Geophysics 99, p. 22,897-22,914; 1994

Y.Q. Wang X.Y. Zhang

Surface observation of sand and dust storm in East Asia

- Investigation of Asian SDS data (CMA) from meteorological stations over the period 2001 to 2006 → more SDS events occurred in 2001 and 2006


S.L. Gong C.H. Zhou X.Q. Hu H.L. Liu T. Niu Y.Q. Yang

and its application in CUACE/Dust

- high PM10 concentrations were always associated with high frequency of SDS events in most areas of northern China - the annual variation of PM10 concentration shows different patterns in different regions - highest monthly mean daily PM10 concentration was observed in April at most SDS stations - a power functional relationships between PM10 and visibility was found among various regions generally with a good correlation - a SDS verification system was developed based on ground–based observational data for data assimilation - operational SDS forecasting system for East Asia: CUACE/Dust system

X. Yue H. Wang Z. Wang K. Fan

Simulation of dust aerosol radiative feedback using the Global Transport Model of Dust: 1. Dust cycle and validation

- the Global Transport Model of Dust (GMOD) is developed within a general circulation model, using comprehensive parameterizations of the emission and deposition processes from Wang et al. (2000) - prediction of average dust emission of 1935 ± 51 Tg a-1 and a global dust burden of 27.8 ± 0.8 Tg (particles smaller than 10 mm) - the simulated interannual variability is small, but the seasonal variation is quite large in the Sahara Desert and central Asia - diurnal variation of dust: dust mobilization is more active during the local daytime than nighttime ↔ dust burden and dry deposition of dust show a similar diurnal cycle peaking in the late afternoon


X. Yue H. Wang H. Liao K. Fan

Simulation of dust aerosol radiative feedback using the GMOD: 2. Dust-climate interactions

- the presence of mineral dust aerosol in the atmosphere is estimated to exert global mean shortwave and longwave radiative forcings (RF) of -0.25 W m2 and +0.27 W m2 (top of the atmosphere (TOA)) and -1.95 W m2 and +0.61 W m2 (surface) - climatic effect of dust is simulated using two different approaches: 1. monthly mean fields of dust simulated a priori (fixed) are used in the radiative transfer module of the GCM to drive climate change 2. dust aerosol interacts online with meteorology through the dust cycle and its direct radiative effect - dust longwave radiative effect is predicted to offset a large portion of its shortwave effect on a global and annual mean basis - dust shortwave effect dominates during the daytime, and the longwave effect prevails at night - the solar radiative effect reduces dust emissions by increasing surface humidity and by reducing surface wind speed, while the thermal effect increases dust uplift through opposite changes in the meteorological parameters


E. M. Zubler D. Folini U. Lohmann D. Lüthi

Implementation and evaluation of aerosol and cloud microphysics in a regional climate model

- daytoday variability may be controlled more by the meteorology (aerosol washout or accumulation locally) than the emissions - new regional aerosol modeling framework enables the study of the whole diversity


A. Muhlbauer S. Pousse-Nottelmann C. Schär M. Wild

of interactions between aerosols, clouds, radiation and precipitation on climatological time scales

Impact on climate system authors title contents publication P. Alpert J. Herman Y.J. Kaufman I. Carmona

Response of the climatic temperature to dust forcing, inferred from total ozone mapping spectrometer TOMS/aerosol index and the NASA assimilation model

- atmospheric climatic response of the temperature field to the radiative forcing of the dust layer over the subtropical deserts is shown - resulting heating rate increases linearly up to about 0.4 Krday within the dust layer at 4 km and is in agreement with calculated heating rates

Atmospheric Research 53, Issues 1-3, p. 3–14; 2000

P.R. Buseck M. Pósfai

Airborne minerals and related aerosol particles: Effects on climate and the environment

- Minerals are a highly heterogeneous mixture - its injection rate into the atmosphere can vary temporally and spatially, e.g., as a result of dust storms, volcanic eruptions, and anthropogenic activities - due to relatively short atmospheric lifetime the dust radiative forcing adjusts relatively rapidly to changes in emissions - Mineral-dust particles provide important reactive surfaces for atmospheric reactions - An annual average of 40% (locally reaching 70%) of total sulfate is associated with mineral dust over Asia, the western United States, Australia, and North Africa - The mineral particles, being partly coated with hygroscopic sulfates—sometimes as the result of cloud processing—can also become CCN. - atmospheric transport of mineral dust is widespread and can have major effects on life at the bottom of the food chain in the large areas of the oceans that are far from the nutrients


J. Haywood O. Boucher

Estimates of the direct and indirect radiative forcing due to tropospheric aerosols: a review

- the indirect effect is split into two components corresponding to the radiative forcing due to modification of the radiative properties of clouds (cloud albedo effect) and the effects of anthropogenic aerosols upon the lifetime of clouds (cloud lifetime effect) - distinction between 6 major types of aerosols: sulphate aerosol (anthropogenic), fossil fuel black carbon (anthropogenic), biomass-burning black carbon, biomass burning organic carbon, mineral dust, nitrates - ranges of RF for each type of aerosol can be found in the paper - available models predict that the radiative flux perturbation associated with the cloud lifetime effect is of a magnitude similar to that of the cloud albedo effect

Reviews of Geophysics 38(4), p. 513–543; 2000

S.P. Harrison K.E. Kohfeld C. Roelandt T. Claquin

The role of dust in climate changes today, at the last glacial maximum and in the future

- Natural mineral aerosol (dust) plays multiple roles in mediating physical and biogeochemical exchanges between the atmosphere, land surface and ocean - Changes in the amount of dust are caused by changes in climate (precipitation, wind strength, regional moisture balance) and changes in the extent of dust sources (anthropogenic or climatically induced changes in vegetation cover) - Atmospheric dust loading was as much as an order-of-magnitude

Earth-Science Reviews 54, Issues 1-3, p. 43-80; 2001

larger than today during the last glacial maximum (LGM) - increase in emissions from northern Africa can ↔ direct effect of climate changes, increased emissions from other regions ↔ indirect: climatically induced changes in vegetation cover - anthropogenically forced climate changes substantially reduce the extent and productivity of natural dust sources ↔ mitigate the impacts of land-use changes (increases dust loading)

N.M. Mahowald S. Kloster S. Engelstaedter J.K. Moore S. Mukhopadhyay J.R. McConnell S. Albani S.C. Doney A. Bhattacharya M.A.J. Curran M.G. Flanner F.M. Hoffman D.M. Lawrence K. Lindsay P.A. Mayewski J. Neff D. Rothenberg E. Thomas P.E. Thornton C.S. Zender

Observed 20th century desert dust variability: impact on climate and biogeochemistry

- reconstruction of desert dust variability over the 20th century based on observational and model synthesis - most important: North African, East Asian and Middle East/Central Asian sources - the results suggest that desert dust roughly doubled over the 20th century over much, but not all the globe - largest estimated differences: between the dusty 1980–1989 period compared to the relatively dust-free 1955–1964 period - including desert dust fluctuations in climate model simulations improves our ability to simulate decadal scale variability in global surface temperature, regional changes in temperature and precipitation and possibly explains the residual global carbon flux unexplained by other mechanisms

Atmospheric Chemistry and Physics 10, p. 10875–10893; 2010 doi: 10.5194/acp-10-10875-2010

R.L. Miller J. Perlwitz I. Tegen

Feedback upon dust emission by dust radiative forcing through the planetary boundary layer

- indication that dust radiative forcing in the present-day climate reduces emission of dust into the atmosphere ↔ interaction between dust radiative forcing and the planetary boundary layer (PBL) - by reducing sunlight incident upon the surface, dust decreases the turbulent flux of sensible heat into the atmosphere → reduces turbulent mixing within the PBL → decrease of surface wind speed and dust emission - at some of the most productive source regions, morning emission is reduced in proportion to the surface radiative forcing


R. L. Miller I. Tegen

Climate Response to Soil Dust Aerosols

- the radiative effect of soil dust aerosols is to redistribute heating from the surface to within the dust layer → reductions in mineral aerosols may increase surface temperatures

Journal of Climate 11, p. 3247–3267; 2010

J.E. Penner M. Andreae H. Annegarn L. Barrie

Aerosols, their direct and indirect effects

- description of the role of aerosols in the climate system (direct and indirect effects)

Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate

J. Feichter D. Hegg A. Jayaraman R. Leaitch D. Murphy J. Nganga G. Pitari

Change (IPCC) [Houghton, J.T.,Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, K. Maskell, and C.A. Johnson (eds.)], chapter 5, Cambridge University Press; 2001

J.M. Prospero P.J. Lamb

African Droughts and Dust Transport to the Caribbean: Climate Change Implications

- nonmarine aerosols have doubled in the last 50–100 years, because of expansion of population and economic activity by factor of 3, and a doubling in Saharan dust production

Science 302(5647), p. 1024-1027; 2003 doi: 10.1126/science.1089915

A. Slingo T.P. Ackerman R.P. Allan E.I. Kassianov S.A. McFarlane G.J. Robinson J.C. Barnard M.A. Miller J.E. Harries

J.E. Russell S. Dewitte

Observations of the impact of a major Saharan dust storm on the Earth's radiation balance

- major perturbations to the solar and thermal radiative fluxes both at the top of the atmosphere and at the surface were observed - combination of the long-term AMF measurements made in Niamey and the satellite data provide a new opportunity to study the radiative properties of the atmosphere and to construct test cases for evaluating and improving models


I. Tegen A.A. Lacis I. Fung

The influence on climate forcing of mineral aerosols from disturbed soils

- model calculations indicate that 50 20% of the total atmospheric dust mass originates from disturbed soils (those affected by cultivation, deforestation, erosion and frequent shifts in vegetation due to droughts and rains) - dust from disturbed soils causes a decrease of the net surface radiation forcing of about 1Wm-2, accompanied by increased atmospheric heating that may be a significant forcing of atmospheric dynamics

Nature 380, p. 419 – 422; 1996 doi: 10.1038/380419a0

A direct effects (radiation effects) authors title contents publication P. Alpert Y.J. Kaufman Y. Shay-El D. Tanre A. da Silva S. Schubert J.H. Joseph

Quantification of dust-forced heating of the lower troposphere

- large dust particles interact with thermal radiation - dust aerosols are an important source of inaccuracies in numerical weather prediction models in this region (eastern tropical North Atlantic Ocean) - average dust event: dust is estimated to heat the lower atmosphere (1.5–3.5km altitude) by 0.2 K per day → regional heating rate of 6 K per year

Nature 395(24); 1998

T.N. Carlson S.G. Benjamin

Radiative Heating Rates for Saharan Dust

- a combined longwave and shortwave radiative transfer model was used

Journal of Atmospheric Sciences 37, Issue 1, p.193-213; 1980

- cloud-free and overcast conditions over the ocean and for cloud-free sky over desert - moderately heavy dust amounts → calculated aerosol heating rates were in excess of 1 K day for most of the atmosphere beneath the top of the dust layer (500 mb) - Net fluxes determined at the top of the atmosphere for the ocean cloud-free case were very insensitive to changes in dust optical depth - For the cloudy oceanic and desert cases, the reflectivity of the earth-atmosphere system diminished with increasing dust optical depth - the dust reduced the downward radiative flux into the ocean or desert while at the same time it increased the heating in the atmosphere, thus indicating a stabilizing effect by dust on the temperature lapse

J. Dufresne C. Gautier P. Ricchiazzi Y. Fouquart

Longwave Scattering Effects of Mineral Aerosols

- Scattering in the longwave domain is not negligible for cloudy conditions - When the effective radius is greater then a few tenths of a micron, scattering contributes to longwave forcing at the TOA at a level of 20% to 60% - Scattering has less impact on surface forcing (about 5% to 20%) and has negligible impact on atmospheric heating rate - relative errors do not depend on the aerosol optical thickness but mainly on the aerosol size distribution and aerosol refractive index - the main effect of scattering is to backscatter the upwelling flux emitted by the surface (between 8 and 13 μm)

Journal of Atmospheric Science 59, p. 1959–1966; 2002

J.E. Hansen M. Sato R. Ruedy

Radiative forcing and climate response

Journal of Geophysical Research 102, p. 6831–6864; 1997

O.V. Kalashnikova I.N. Sokolik

Modeling the radiative properties of nonspherical soil-derived mineral aerosols

- Mineral dust aerosols have complex nonspherical shapes and varying composition - dust particle composition–shape–size (CSS) distributions are reconstructed from the electron microscopy data, the effective medium and discrete dipole is approximated - CSS distributions result in various differences in the extinction coefficient, single scattering albedo, asymmetry parameter and the scattering phase function relative to the volume-equivalent spheres and the mixtures of the randomly oriented oblate and prolate spheroids

Journal of Quantitative Spectroscopy and Radiative Transfer 87, Issue 2, p. 137-166; 2004

Y.J. Kaufman D. Tanré O. Dubovik A. Karnieli L.A. Remer

Absorption of sunlight by dust as inferred from satellite and groundbased remote sensing

- two new independent remote sensing techniques demonstrate that Saharan dust absorption of solar radiation is several times smaller than the current international standards. For example, at wavelength of 0.64 µm the dust single scattering albedo is reported here as 0.97±0.02 rather than 0.87±0.04 in recent review.

Geophysical Research Letters 28(8), p. 1479–1482; 2001 doi:10.1029/2000GL012647

S. Lafon I.N. Sokolik J.L. Rajot

Characterization of iron oxides in mineral dust aerosols: Implications for

- several dust samples were analyzed for their total and free iron content, iron oxide mineralogy, and particle size distribution - measurements demonstrated that the total iron content (as a percentage of total mass) varies little between the samples regardless


S. Caquineau A. Gaudichet

light absorption of their origin or aging - Fe/Al ratios do vary depending on dust origin (Chinese dust sample has the highest Fe/Al ratios relative to Niger and Tunisian) - free iron takes between 25% and 75% of the total iron mass depending on a particular sample. It shows more variability than the total iron content does → affects the single-scattering albedo of aggregates and external mixtures with minerals - the free iron content and free-Fe/Al ratios are larger in coarse particles compared to fine ones → large differences in the single-scattering albedo - in each sample, we found more goethite than hematite → considering hematite or goethite in optical calculation leads to large differences - the real part of the effective refractive index of aggregates depends on the mineralogy of both iron oxides (hematite versus goethite) and clays (illite versus kaolinite), while the imaginary part is controlled mainly by the volume fraction of iron oxides - the extinction coefficient of aggregates depends little on their mineralogy

M. Mallet P. Tulet D. Serc F. Solmon O. Dubovik J. Pelon V. Pont O. Thouron

Impact of dust aerosols on the radiative budget, surface heat fluxes, heating rate profiles and convective activity over West Africa during March 2006

- study based on numerical MesoNH simulations coupled with experimental AMMA observations - the presence of dust particles induces a large instantaneous (at noon) reduction of surface incoming shortwave radiation over a large part of West Africa during the 9 to 12 March period - the surface dimming resulting from the presence of dust is shown to cause important reductions in both the surface temperature and in sensible heat fluxes - the net effect (shortwave+longwave) at TOA is dominated by the SW one although the mean positive LW effect compensates about half of the mean negative SW one → presence of dust plumes cools the earth-atmosphere system - the atmospheric heating rate changes induced by dust show large SW heating (at noon) within the dusty layer (2–4 km) due to strong absorption of the incoming solar radiation, in the LW, a significant cooling is obtained below the dust layer (0–1 km ↔ surface temperature decrease which strongly reduces surface LW emissions and hence warming of lower troposphere layers - surface cooling (aerosol heating in the dust layer) → reduction of convective activity → decrease of CAPE

Atmospheric Chemistry and Physics Discussion 9, p. 2967–3006; 2009

G. Myhre F. Stordal

Global sensitivity experiments of the radiative forcing due to mineral aerosols

- two global data sets of mineral aerosol distribution are used - the sensitivity of the global radiative forcing to the spatial distribution of the aerosols, including the altitude, the size distribution, and optical parameters is investigated - a strong sensitivity is found for the size distribution of the mineral aerosol

Journal of Geophysical Research 106(D16), p. 18,193-18, 204; 2001 doi:10.1029/2000JD900536

S.K. Satheesh Radiative effects of natural - Natural aerosols are particularly important because they provide a Atmospheric Environment Volume 39,

K. Krishna Moorthy aerosols: A review kind of base level to aerosol impact → on a global scale the abundance of natural aerosols (sea salt, soil dust, natural sulphates, volcanic aerosols, and those generated by natural forest fires) is several times greater than that of the major anthropogenic aerosols (sulphate, soot and organics). - The mineral dust transported over land and ocean causes surface cooling (due to scattering and absorption) simultaneously with lower atmospheric heating (due to absorption) → perturbations in the regional and global climate. - Even though direct radiative impacts due to sea salt and natural sulphate are small compared to those due to anthropogenic counterparts, their indirect effects (and the uncertainties) are much larger

Issue 11, p. 2089-2110; 2005

I.N. Sokolik O.B. Toon

Direct radiative forcing by anthropogenic airborne mineral aerosols

- Various human activities, such as land use practices, can result in additional loading of dust, increasing the radiative forcing - the forcing by anthropogenically generated mineral aerosols may be comparable to the forcing by other anthropogenic aerosols - on a regional scale the forcing due to mineral aerosols can greatly exceed that due to sulphate aerosols and can be comparable to that of clouds

Nature 381, p. 681-683; 1996 doi:10.1038/381681a0

I.N. Sokolik O.B. Toon

Incorporation of mineralogicalcomposition into models of the radiative properties of mineral aerosol from UV to IR wavelengths

- dust aerosols can have a negative or positive radiative forcing depending on their mineralogical composition

Journal of Geophysical Research 104, p. 9423–9444; 1999

G. Stanhill S. Cohen

Global dimming: a review of the evidence for a widespread and significant reduction in global radiation with discussion of its probable causes and possible agricultural consequences

- global dimming of sunlight at the surface over the land in the last 50 years of 10–20 W_m2 is observed ↔ higher aerosol concentrations over the land, near the sources, than over the ocean

Agricultural and Forest Meteorology 107, Issue 4, p. 255-278; 2001

I. Tegen A.A. Lacis

Modeling of particle size distribution and its influence on the radiative properties of mineral dust aerosol

- The radiative parameters of mineral aerosols are strongly dependent on particle size → explicit modeling of particle size distribution is needed → eight size classes between 0.1 and 10 μm - initial size distribution ↔ soil texture data and aerosol size measurements close to the ground - size distribution changes during transport as larger particles settle out faster than smaller particles - results of Mie scattering calculations → regional changes in radiative flux at the top of the atmosphere as large as +15 Wm−2 at solar and +5 Wm−2 at thermal wavelengths in the annual mean → dust forcing is an important factor in the global radiation budget


B Semi-direct effect authors title contents publication J. Huang B. Lin P. Minnis T. Wang X. Wang Y. Hu Y. Yi J.K. Ayers

Satellite-based Assessment of Possible Dust Aerosols Semi-Direct Effect on Cloud Water Path over East Asia

- the mean ice water path (IWP) and liquid water path (LWP) of dusty clouds are smaller than in dustfree clouds in the same frontal systems - there is significant negative correlation between dust storm index and ISCCP cloud water path → dust aerosol warming effect through the absorption of solar radiation: dust aerosols in warm clouds increase the evaporation of cloud droplets and further reduce cloud water path (semi-direct effect) - less important for Saharan dust ↔ different composition → may play a role in cloud development over arid and semi-arid areas of East Asia and contribute to the reduction of precipitation (dominanting factor of dust-aerosol-cloud interaction in Asia) → reduces cloud cooling effect → desertification due to dust storms in Northwest China during recent decades


J. Perlwitz R.L. Miller

Cloud cover increase with increasing aerosol absorptivity: A counterexample to the conventional semidirect aerosol effect

- according to the conventional description of the semidirect effect, tropospheric aerosols that absorb radiation decrease relative humidity and cloud cover - in our simulations, low cloud cover increases due to radiative forcing by absorbing aerosols in high-dust AOD regions (dust AOD_0.1) during Northern Hemisphere spring, summer (strongest increase), and fall and in low-dust AOD regions over sea during all seasons; microphysical effects of dust aerosols acting as cloud droplet nuclei were not included - the increase of specific humidity in the lower troposphere overwhelms the warming effect of the absorbing aerosols on relative humidity in high-dust regions (except in Northern Hemisphere winter) and in low dust regions over the oceans, leading to an increase in low cloud cover - in our experiments, radiative forcing by soil dust aerosols has a significant effect on climate, not just in regions with high dust AOD but also in remote regions via large-scale circulation changes - we hypothesize that diabatic heating by absorbing aerosols in the rising branch of a direct circulation tends to enhance the ascent, increasing moisture convergence, low cloud cover (and even medium and high cloud cover), and precipitation depending on the strength of the radiative forcing in areas in which convection occurs - highly reflecting aerosols at the same location would have the opposite effect on circulation, clouds, and precipitation


C Indirect effects (cloud physics) authors title contents publication

F. Bréon D. Tanré S. Generoso

Aerosol effect on cloud droplet size monitored from satellite

- Cloud droplet size is found to be largest (14 micrometers) over remote tropical oceans and smallest (6 micrometers) over highly polluted continental areas, small droplets are also present in clouds downwind of continents → effect of aerosols on cloud microphysics is significant and occurs on a global scale - the cloud droplet size appears to be better correlated with an aerosol index that is representative of the aerosol column number under some assumptions than with the aerosol optical thickness

Science 295, p. 834-838; 2002

M. J. Costa E. Cattani A.M. Silva V. Levizzani

Satellite derived cloud properties relevant for cloud radiative forcing: a case study of interaction between clouds and dust aerosol particles

- decrease of the cloud droplet effective radius when dust aerosol particles were present over the area and at the same atmospheric levels - clouds that come in contact with dust particles are affected by them: particles grow less and this most probably affects precipitation (diminishing/suppressing)

International Conference on clouds and Precipitation (ICCP) 2004

A. Givati D. Rosenfeld

Quantifying Precipitation Suppression Due to Air Pollution

Aerosols reduce vital water resources in densely populated semi-arid regions by suppressing precipitation

Journal of Applied Meteorology and Climatology 43, p. 1038–1056; 2004

H. Jiang H. Xue A. Teller G. Feingold Z. Levin

Aerosol Effects on the Lifetime of Shallow Cumulus

- increase in aerosol concentration from very clean to very polluted does not increase cloud lifetime (statistically similar although individual clouds may experience decreases in lifetime of 10-40%), even though precipitation is suppressed ↔ small changes in cloud lifetime are due to competing effects of precipitation suppression and enhanced evaporation, with the latter tending to dominate in these shallow clouds

Geophysical Research Letters 33, L14806; 2006 doi: 10.1029/2006GL026024

Y.J. Kaufman I. Koren L.A. Remer D. Rosenfeld Y. Rudich

The effect of smoke, dust, and pollution aerosol on shallow cloud development over the Atlantic Ocean

- Clouds developing in a polluted environment tend to have more numerous but smaller droplets → may lead to suppression of precipitation and longer cloud lifetime - Absorption of incoming solar radiation by aerosols can reduce the cloud cover - coverage of shallow clouds increases by 0.2–0.4 with increases in the aerosol column concentration from clean to polluted, smoky, or dusty conditions → increase in the optical thickness from 0.03 to 0.5 and extend of the coverage thousands of kilometers (smoke and dust) - changes accompanied by reduction in cloud droplet size by 10–30% - accompanied by liquid water increase (all but the smoke region) - forcing observed by aerosol-induced increase in cloud coverage exceeds that due to aerosol-induced changes in cloud drop concentrations alone by a factor of 3–5 → traditional estimates of aerosol-cloud forcing, which focused on cloud top brightness, underestimate the aerosol climatic effects

Proceedings of the National Academy of Sciences 102(32), p. 11207-11212; 2005 doi: 10.1073/Proceedings of the National Academy of Sciences. 0505191102

A. Khain P.N. BenMoshe A. Pokrovsky

Factors determining the impact of aerosols on surface precipitation from clouds: An attempt at classification

- in-creased CCN and ice nuclei can increase or decrease precipitation and convective intensity, depending on environmental conditions (air humidity…), cloud types and the stage in the storm’s lifecycle - clouds developing in dry air: decrease in the accumulated precipitation with the aerosol concentration increase - deep maritime clouds: increase in precipitation

Journal of Atmospheric Science 65, p. 1721–1748; 2008 doi: 10.1175/2007JAS2515.1

A. Khain D. Rosenfeld A. Pokrovsky

Aerosol impact on the dynamics and microphysics of deep convective clouds

- the ‘aerosol effect’ on precipitation can be understood only in combination with the ‘dynamical effect’ of aerosols - maritime aerosols lead to a rapid formation of raindrops that fall down through cloud updraughts increasing the loading in the lower part of a cloud - increase in CCN → formation of a large number of small droplets with a low collision rate → time delay of raindrop formation → prevents a decrease in the vertical velocity caused by the falling raindrops → increases the duration of the diffusion droplet growth stage, increasing latent heat release by condensation - additional water rises to the freezing level increases latent heat release by freezing → larger vertical velocities, attain higher levels - aerosols, which decrease the precipitation efficiency of most single clouds, can contribute to the formation of very intensive convective clouds and thunderstorms (e.g. squall lines, etc.) accompanied by very high precipitation rates → influences net heating of the atmosphere and its vertical distribution, as well as cloud depth and cloud coverage, atmospheric motions and radiation balance at different scales, from convective to, possibly, global ones

Quarterly Journal of the Royal Meteorological Society 131, p. 2639–2663; 2005 doi: 10.1256/qj.04.62

Z. Levin E. Ganor V. Gladstein

The effects of desert particles coated with sulfate on rain formation in the eastern Mediterranean

- mineral dust particles often get coated with sulfate and other soluble materials related to the surface area of the particles (deposition process could be surface dependent) → effective giant CCN → large drops (20-40 μm) → affects the precipitation development

Journal of Applied Meteorology and Climatology 35, p. 1511-1523; 1996

B.G. Liepert J. Feichter U. Lohmann E. Roeckner

Can aerosols spin down the water cycle in a warmer and moister world?

- reductions in surface solar radiation due to clouds and aerosols are only partly offset by enhanced down-welling longwave radiation from the warmer and moister atmosphere - radiative imbalance at the surface leads to weaker latent and sensible heat fluxes and hence to reductions in evaporation and precipitation despite global warming


U. Lohmann C. Hoose

Sensitivity studies of different aerosol indirect effects in mixed-phase clouds

- glaciation effect: more frequent glaciation due to anthropogenic aerosols - de-activation effect: ice nuclei become less effective because of an anthropogenic sulfate coating - glaciation effect can partly offset the indirect aerosol effect on warm clouds and thus causes the total anthropogenic aerosol effect to be smaller - importance of these effects is investigated by varying the parameterization for the onset of the Bergeron-Findeisen process and the threshold coating thickness of sulfate (SO4-crit), which is required to convert an externally mixed aerosol particle into an internally mixed particle - differences in the net radiation at the top-of-the-atmosphere due to anthropogenic aerosols between the different sensitivity studies


amount up to 0.5Wm−2 → investigated mixed phase processes have a major effect on the total anthropogenic aerosol effect - when SO4-crit is increased, more mineral dust particles remain externally mixed and can act as contact ice nuclei → initiate freezing at a higher temperature than immersion freezing initiated by internally mixed BC and dust aerosols

U. Lohmann J. Feichter

Global indirect aerosol effects: a review

- Aerosols affect the climate system by changing cloud characteristics in many ways → act as cloud condensation and ice nuclei, they may inhibit freezing and they could have an influence on the hydrological cycle - aerosol effects on clouds can be divided into the radiative effects and the effects on the hydrological cycle - Both the Twomey and the cloud lifetime effect act to cool the Earth-atmosphere system by increasing cloud optical depth (albedo enhancement) and cloud cover, respectively. This reduces the net solar radiation at the top-of-the atmosphere as well as at the surface - Carbonaceous aerosols and dust exert a positive forcing at the top-of-the atmosphere, at least in regions with high surface albedo, and can thus directly warm the atmosphere. This effect can be amplified if absorption of solar radiation of these aerosol particles occurs within cloud droplets. The resulting increase in temperature reduces the relative humidity and may result in the evaporation of cloud droplets. The reduced cloud cover and cloud optical depth will in turn further amplify warming of the Earth-atmosphere system - Another way in which aerosols could contribute to a warming is by decreasing cloud amount due to increasing precipitation. As more aerosols generally lead to more and smaller cloud droplets, this effect is not very likely to happen but may occur if a few anthropogenic aerosol were to act as giant nuclei or as ice nuclei - Aerosol effects on the hydrological cycle: suppression of drizzle, change of the occurrence and frequency of convection, reductions in the net solar radiation reaching the surface → evaporation could decrease and the hydrological cycle could be expected to slow down - Aerosol induced cooling of the Northern Hemisphere causes a southward shift of the intertropical convergence zone, which could have been partly responsible for the Sahelian drought


N.M. Mahowald L.M. Kiehl

Mineral aerosol and cloud interactions

- relationship between mineral aerosols and cloud properties over North Africa and the North Atlantic is considered - mineral aerosols from North Africa have increased substantially since the 1960s for reasons which are poorly understood but that may be linked to human activity. - Positive correlations of up to 0.4 between anomalously high dust months and thin low clouds are consistent with mineral aerosols acting as cloud condensation nuclei off the west coast of North Africa during dust events, and suppressing precipitation - low negative correlations (-0.2 to -0.3) between high ice clouds

Geophysical Research Letters 30(9), p. 1475; 2003 doi: 10.1029/2002GL016762

(cirrus, stratocirrus and deep convective) and high dust months close to equator in North Africa and the Atlantic - positive anomalies (0.2 to 0.3) in the western equatorial North Atlantic associated with more northerly negative anomalies indicating a shift in ice-phase clouds

J.B. Nee C. Chiang H. Hu S. Hu J. Yu

Lidar measurements of Asian dust storms and dust cloud interactions

- dust transport to the south may interact strongly with the moisture from the active weather system in the region producing significant climate effects - dust particles with enhanced soluble coatings are related to the interaction of dust particles with pollution during transport - coated dust particles can act as giant CCN to form clouds → deposition and cloud chemistry

Journal of Geophysical Research 112, D15202; 2007 doi: 10.1029/2007JD008476

M. Pasqui B. Gozzini F. Pasi

Sahara dust impact on precipitation severe storm events over West-Central Mediterranean Area

- aerosols, as cloud condensation nuclei (CCN), act as an indirect forcing on the precipitation produced by microphysics schemes


V. Ramanathan P. J. Crutzen J. T. Kiehl D. Rosenfeld

Aerosols, Climate, and the Hydrological Cycle

- human-made aerosols enhance scattering and absorption of solar radiation and produce brighter clouds that are less efficient at releasing precipitation → large reductions in the amount of solar irradiance reaching Earth's surface → increase in solar heating of the atmosphere → changes in the atmospheric temperature structure → suppression of rainfall → less efficient removal of pollutants → weaker hydrological cycle ↔ availability and quality of fresh water

Science 7, 294(5549), p. 2119-2124; 2001 doi: 10.1126/science.1064034

D. Rosenfeld Y. Rudich R. Lahav

Desert dust suppressing precipitation: A possible desertification feedback loop

- clouds forming within desert dust contain small droplets and produce little precipitation by drop coalescence - the detrimental impact of dust on rainfall is smaller than that caused by smoke from biomass burning or anthropogenic air pollution - reduction of precipitation from clouds affected by desert dust can cause drier soil, which in turn raises more dust (feedback loop) - anthropogenic changes of land use can initiate such a desertification feedback process


K. Sassen P.J. DeMott J.M. Prospero M.R. Poellot

Saharan dust storms and indirect aerosol effects on clouds: CRYSTAL-FACE results

- mineral dust particles transported from Saharan Africa to Florida are effective ice nuclei - The data indicate that the properties of Saharan dust are similar to those from Asian deserts in terms of their potential for indirect cloud effects

Geophysical Research Letters 30(12), p. 1633; 2003 doi: 10.1029/2003GL017371

S. Solomos G. Kallos J. Kushta M. Astitha C. Tremback A. Nenes Z. Levin

An integrated modeling study on the effects of mineral dust and sea salt particles on clouds and precipitation

- “Hazy” aerosol conditions delayed precipitation while the clouds that were formed in a “pristine” environment precipitated faster and produced more rain - distribution of accumulated precipitation was found to be much more sensitive to topographic variations than to aerosol number concentration and/or composition → macroscopic vs. microscopic interaction - increase of 15% in the concentration of soluble dust particles produced clouds that extended about three kilometers higher and the


initiation of precipitation was delayed by almost one hour - variations between 1–30% in the amount of dust particles that were assumed to contain soluble material resulted in significant changes in cloud properties - online treatment of dust and salt particles as prognostic CCN, GCCN and IN improves the bias score for the 24 h accumulated precipitation → highly non-linear response of precipitation to aerosol properties

A. Teller Z. Levin

The effects of aerosols on precipitation and dimensions of subtropical clouds: a sensitivity study using a numerical cloud model

- under the same meteorological conditions polluted clouds (with high CCN concentrations) produce less precipitation than clean clouds (with low CCN concentrations) → the initiation of precipitation is delayed and the lifetimes of the clouds are longer - GCCN enhance the total precipitation in polluted clouds ↔ increased graupel mass in the cloud, partially offsets the decrease in rainfall due to pollution (increased CCN) - addition of more effective IN, such as mineral dust particles, reduces the total amount of precipitation on the ground (more pronounced in clean clouds than in polluted ones) - about 3.5 times more water evaporates after the rain stops from the polluted cloud as compared to the clean cloud


C. Twohy S. Van den Heever S. Kreidenweis T. Eidhammer P. DeMott A. Heymsfield A. Bansemer B. Anderson G. Chen E. Browell

Interaction of Saharan dust with liquid and ice clouds

- Saharan dust acts as CCN - If a fraction of the dust sub-merged in droplets is lifted to cold temperatures in deep convection, a substantial change in ice concentration is likely


S. Twomey Pollution and the planetary albedo

- Aerosols are responsible for decrease of the droplet size due to an increase in droplet concentration and respective enhancement of cloud reflectivity

Atmospheric Environment 8, Issue 12, p. 1251-1256; 1974

Y. Yin S. Wurzler Z. Levin T.G. Reisin

Interactions of mineral dust particles and clouds: Effects on precipitation and cloud optical properties

- insoluble mineral dust particles become effective cloud condensation nuclei (CCN) after passing through a convective cloud → the more times these particles go through clouds, the larger the mass of soluble material they accumulate → effectiveness as CCN increases by coating with sulfate (due to evaporation of hydrometeors) - in continental clouds the effect of cloud-processed dust particles is to accelerate the formation of precipitation particles, in maritime clouds the addition of cloud-processed aerosol and mineral dust particles has a minimal effect on precipitation - the addition of more CCN to either maritime or continental clouds increases their optical depth, even for those cases in which the precipitation amount is increased - maritime clouds: the efficiency of precipitation development is high at

Journal of Geophysical Research 107(D23), p. 4724; 2002 doi: 10.1029/2001JD001544

the beginning and the rainfall decreases with addition of more small CCN (added giant CCN cannot compensate for the negative effect of the added small ones)

D Impact on cloud formation (ice nuclei) authors title contents publication P.J. DeMott A.J. Prenni S.M. Kreidenweis F. Collins C.H. Twohy D.C. Rogers

Ice Nuclei Variability and Ice Formation in Mixed-Phase Clouds

- ice nucleating aerosols are critical for the initiation of ice in clouds - mineral dust aerosol particles are sources for IN populations - [IN] depends on temperature, humidity, and time ↔ Cloud properties may be particularly sensitive to IN at certain times and locations, particularly for periods favoring low mineral dust mass loadings and low IN concentrations

Sixteenth ARM Science Team Meeting Proceedings, Albuquerque, NM, March 27 – 31; 2006

P.J. DeMott K. Sassen D. Baumgardner D.C. Rogers S.D. Brooks A.J. Prenni S.M. Kreidenweis

African dust aerosols as atmospheric ice nuclei

- concentrations of ice nuclei within dust layers at particle sizes below 1 μm exceeded 1 cm−3 (Florida, origin: Africa) with device at temperatures warmer than homogeneous freezing conditions → ice nucleation efficiency of desert dust aerosols, confirmation of great distances from source regions → mineral dust as ice nuclei can lead to the formation of cirrus clouds at much higher temperatures than normally thought

Geophysical Research Letters 30(14), p. 1732; 2003 doi: 10.1029/2003GL017410.

P.J. DeMott K. Sassen M.R. Poellot D. Baumgardner D.C. Rogers S.D. Brooks A.J. Prenni S.M. Kreidenweis

African dust aerosols as atmospheric ice nuclei

- the concentrations of ice nuclei within dust layers at particle sizes below 1 mm exceeded 1 cm-3 (at temperatures warmer than homogeneous freezing conditions!) - desert dust aerosols are really efficient ice nuclei, also at great distances from source regions

Geophysical Research Letters 30(14), p. 1732; 2003 doi:10.1029/2003GL017410

M.L. Eastwood S. Cremel C. Gehrke E. Girard A.K. Bertram

Ice nucleation on mineral dust particles: Onset conditions, nucleation rates and contact angles

- significant differences in the ice nucleating ability of different minerals - Kaolinite and muscovite = efficient ice nuclei in the deposition mode - Quartz and calcite = poor ice nuclei, requiring relative humidities close to water saturation before ice crystals would form (20 to 40% higher than those needed for kaolinite and muscovite) - Montmorillonite = efficient ice nuclei at temperatures below 241 K, but poor ice nuclei at higher temperatures (244.6 K) - contact angles kaolinite and muscovite ranged from 6° to 12°, whereas for quartz and calcite, the contact angles ranged from 25° to 27°



Implications of droplet nucleation to mineral dust aerosol deposition and transport

- the activation threshold radius (ATR) for droplet nucleation is typically found in the range of clay-sized particles (radius = 0.1 to 1.0 mm), a spectrum over which the amount of dust removed declines ~60% both in surface area and particle number - nucleation of silt-sized particles (1.0–10.0 mm) occurs under most


conditions - while acid coating of dust particles in polluted environments acts to decrease the ATR, the effect is reduced by competition with soluble aerosols

P.R. Field O. Möhler P. Connolly M. Krämer R. Cotton A.J. Heymsfield H. Saathoff M. Schnaiter

Some ice nucleation characteristics of Asian and Saharan desert dust

- We observed dual nucleation events during single expansions at temperatures colder than −40°C: 1. deposition nucleation 2. either a further deposition mode exhibited by particles of different sizes or mineralogical/chemical composition or a condensation mode facilitated by the presence of soluble material on the desert dust - At temperatures warmer than −40°C droplets were formed before and at the same time as ice crystals were formed, presumably via and immersion or condensation ice nucleation mode and no deposition mode was observed - The maximum activated fraction of the desert dust sample forming ice varied from 5–10% at −20°C to 20–40% at temperatures colder than −40°C


K. Gierens On the transition between heterogeneous and homogeneous freezing

- heterogeneous ice nucleation could dominate the formation of ambient cirrus in preference to homogeneous freezing of more abundant haze (e.g., sulfate) particles (critical concentrations of heterogeneous ice nuclei) - homogeneous nucleation dominates in regions with updrafts stronger than 20 cm s -1 (with the exception of heavily polluted areas) - air pollution may lead to a higher coverage of cirrus clouds, but then these clouds will be optically thinner

Atmospheric Chemistry and Physics 3, p. 437-446; 2003

C. Hoose U. Lohmann R. Erdin I. Tegen

The global influence of dust mineralogical composition on heterogeneous ice nucleation in mixed-phase clouds

- considered as ice nuclei: two types of mineral dust (montmorillonite and kaolinite) and black carbon - uncoated particles can initiate contact freezing, while coated particles are potential immersion nuclei (active at lower temperatures) - contact freezing by black carbon is the dominating freezing process, due to high black carbon number concentrations, and due to the small particle size and high Brownian collision efficiency of black carbon - freezing on dust occurs in both the contact and immersion freezing modes if the dust is composed of montmorillonite (a highly efficient ice nucleus), and almost exclusively in the contact mode if the dust is composed of kaolinite (a less efficient ice nucleus) - enhanced coating of dust particles → quasi-deactivate kaolinite ice nuclei ↔ glaciation indirect effect (increase of cloud glaciation and precipitation formation resulting from the increase of black carbon ice nuclei resulting from anthropogenic activity) - coating and deactivation of natural IN → less frequent glaciation of mixed-phase clouds → less precipitation via the ice phase, longer cloud lifetimes, increased cloud cover and a higher global cloud albedo → increase in reflected solar radiation - themagnitude of the deactivation effect depends on the freezing efficiency of dust and thus on the mineralogical composition

Environmental Research Letters 3; 2008

- glaciation indirect effect is only apparent in the northern hemisphere, in the southern hemisphere it is masked by changes in sea salt emissions due to variation in surface winds - coating and deactivation counteract each other → total anthropogenic effect on mixed-phase clouds is small compared to the aerosol indirect effect on warm clouds

R. Iannone D.I. Chernoff A. Pringle S.T. Martin A.K. Bertram

The ice nucleation ability of one of the most abundant types of fungal spores found in the atmosphere

- focus: fungal spores from the genus Cladosporium - onset for heterogeneous freezing of pure water droplets containing spores: −28.4 °C - strong dependence between the freezing temperature and the total spore surface area of Cladosporium for a given droplet → mean freezing temperatures for droplets containing 1–5 spores are expected to be approximately −35.1±2.3 °C → fungal spores are ineffective IN at temperatures warmer than −15 °C - assuming: concentration of all types of fungal spores in the atmosphere is ~10 L−1, 50% are of Cladosporium → number of IN from Cladosporium is estimated as ~0.025 L−1 - reason of poor ice nucleation ability of Cladosporium spores compared to the bacterial IN P. syringae: basis of the spore surface of Cladosporium is coated with hydrophobins (a class of hydrophobic proteins); the surface of P. syringae is believed to contain a protein that provides a hydrogen-bonding lattice match to ice - spores of Cladosporium may compete with other active IN such as mineral dust (−25 °C to −35 °C)


H. Klein S. Nickovic W. Haunold U. Bundke M. Ebert L. Schuetz Z. Levin L. Barrie H. Bingemer

Saharan dust and ice nuclei over Central Europe

- ice nuclei and mineral dust are significantly correlated at a Central European mountain site (surface measurements, Eulerian regional dust model DREAM) - highest correlation between IN concentration and aerosol surface area - ice nucleating characteristics of the aerosol with respect to temperature and supersaturation are similar during the dust episode and during the course of the year → dust is always a dominant constituent of ice nucleating aerosols in Central Europe

Atmospheric Chemistry and Physics 10, p. 10211-10221; 2010 doi: 10.5194/acp-10-10211-2010

D.A. Knopf T. Koop

Heterogeneous nucleation of ice on surrogates of mineral dust

- desert mineral dust particles may nucleate ice over a broad RHi range due to the different mineral crystallites contained in naturally occurring mineral dust - pure and sulfuric acid coated dust (ATD) particles nucleate ice at considerably lower relative humidities than required for homogeneous ice nucleation in liquid aerosols - different minerals have different ice nucleation thresholds - no significant difference in the ice nucleation ability of pure and H2SO4 coated ATD particles - below 240 K, ice nucleated on ATD particles by deposition nucleation


- preactivation of dust particles can occur for temperatures as low as 200 K - coating of sulfuric acid does not impede preactivation

K.A. Koehler S.M. Kreidenweis P.J. DeMott M.D. Petters A.J. Prenni O. Möhler

Laboratory investigations of the impact of mineral dust aerosol on cold cloud formation

- A mineral dust surrogate, Arizona Test Dust, was found to require the lowest RHi (at least 10% lower) conditions to initiate ice formation for T<-40 °C - ice formation on 1% of the particles at temperatures warmer than −25 °C was only observed for the polydisperse dust sample, indicating the strong size dependence of the required temperature for a given ice active fraction - ice crystal formation by mineral dust does not occur over a sharply defined range of RHw, as observed for pure soluble particles, such as ammonium sulfate → at a given temperature ice nucleation occurred over a range of 15–30% RHw, whereas ammonium sulfate particles are mostly activated by homogeneous freezing over a range of only 2–4% RHw - in the warmer (mixed-phase) cloud regime, water saturation becomes a requirement for significant ice formation - even small fractions of dust particles freezing can impact cloud and precipitation development


Y.H. Lee K. Chen P.J. Adams

Development of a global model of mineral dust aerosol microphysics

- evaluation of dust predictions with dust surface mass concentrations and deposition fluxes shows reasonably good prediction in dusty regions, but more severe underpredictions in remote regions such as near the equator - poor model predictions in remote areas are perhaps due to the GCM meteorology and/or the difficulty of capturing smaller-scale local emissions with a global dust emissions parameterization - dust particles in the model do not influence CCN(0.2% supersaturation) concentrations in most parts of the globe but have significant impacts in dust regions → CCN(0.2%) concentrations in dusty areas decreased up to 20% ↔ additional aerosol surface area provided by dust causing a suppression of H2SO4 concentrations and less condensational growth of ultrafine particles to CCN sizes - effect of dust on CCN is highly sensitive to uncertainties in the dust emissions size distribution


U. Lohmann Possible Aerosol Effects on Ice Clouds via Contact Nucleation

- contact nucleation depends on the aerosol diffusivity which is strongly size dependent (larger particle: contact nucleation is less efficient) - as sulfate aerosols are mainly anthropogenic, this difference in contact nuclei could be taken as the anthropogenic impact on contact nucleation ↔ in reality, some natural sulfate, nitrate or organics could have formed an internal mixture with dust and some dust in an internally mixed aerosol could act as an immersion nuclei that would reduce this effect even more - sizedependence → aerosol diffusivity larger changes in ice clouds can be expected from anthropogenic emissions of smaller insoluble

Journal of Atmospheric Science 59, p. 647–656; 2002 doi: 10.1175/1520-0469(2001)059<0647:PAEOIC>2.0.CO;2

carbonaceous aerosols U. Lohmann K. Diehl

Sensitivity Studies of the Importance of Dust Ice Nuclei for the Indirect Aerosol Effect on Stratiform Mixed-Phase Clouds

- two different background dust types are investigated: kaolinite (KAO) and montmorillonite (MON) - In simulation with KAO black carbon has a higher relevancy as an ice nucleus, because kaolinite is not freezing as effectively as montmorillonite - montmorillonite serves as a contact ice nucleus at the highest temperatures followed by kaolinite and then by black carbon - KAO: the addition of black carbon results in a larger ice water path and a slightly higher precipitation rate in the present-day climate as compared to preindustrial conditions, and a reduced total cloud cover - MON: the increase in the ice water path is much smaller, and globally the change in precipitation is dominated by the reduction in warm-phase precipitation due to the indirect cloud lifetime effect - In all simulations, the change in longwave radiation at the TOA is not negligible (varies between 1.8 and −1.2 W m−2)

Journal of Atmospheric Science 63, p. 968–982; 2006 doi: 10.1175/JAS3662.1

U. Lohmann C. Hoose

Sensitivity studies of different aerosol indirect effects in mixed-phase clouds

- When SO4-crit is increased, more mineral dust particles remain externally mixed and can act as contact ice nuclei → initiate freezing at a higher temperature than immersion freezing initiated by internally mixed BC and dust aerosols


U. Lohmann B. Kärcher J. Hendricks

Sensitivity studies of cirrus clouds formed by heterogeneous freezing in the ECHAM GCM

- Cirrus clouds can form by homogeneous and heterogeneous ice nucleation mechanisms at temperatures below 235 K - If the number of freezing nuclei is limited by the number of black carbon and dust aerosols, then heterogeneous freezing results in fewer ice crystals than formed by homogeneous freezing → these fewer ice crystals grow more readily to precipitation size → increase the global mean precipitation/decrease the ice water path → trap less outgoing longwave radiation at the top of the atmosphere


O. Möhler P.R. Field P. Connolly S. Benz H. Saathoff M. Schnaiter R. Wagner R. Cotton M. Krämer A. Mangold A.J. Heymsfield

Efficiency of the deposition mode ice nucleation on mineral dust particles

- mineral dust = very efficient deposition ice nuclei → Heterogeneous ice nucleation already at ice saturation ratios Si below 1.2 (most cases below 1.1) - the ice nucleation activity is also influenced by other than size distribution: particle properties like surface roughness or mineralogical composition - the ice activation spectrum is almost independent of the cooling rate and the total aerosol number concentration - the formation of new ice particles is always correlated with an increase of Si


M.S. Richardson P.J. DeMott S.M. Kreidenweis D.J. Cziczo E.J. Dunlea

Measurements of heterogeneous ice nuclei in the western United States in springtime and their relation to aerosol characteristics

- soluble coatings on IN would potentially alter ice nucleation mechanisms, inhibiting nucleation by vapor deposition and favoring condensation-freezing nucleation


J.L. Jimenez D.S. Thomson L.L. Ashbaugh R.D. Borys D.L. Westphal G.S. Casuccio T.L. Lersch G. Roberts G. Mauger O. Hadley V. Ramanathan

North American and Asian aerosols over the eastern Pacific Ocean and their role in regulating cloud condensation nuclei

- new particle formation occurs in thin stratified layers between 1000 and 7000 m - ultra-fine aerosols neither effectively scatter light nor immediately serve as CCN - aged, long-range transport aerosols effectively scatter light and serve as CCN - CCN activation index: ratio of critical diameter of ammonium sulfate to measured critical diameter at a given supersaturation - Cloud-processed aerosols exhibit an activation index closest to unity, while aged, long-range transport had values less than one third → long-ranged transport aerosols contribute more to the direct effect than the indirect effect


D.C. Rogers P. J. DeMott L.O. Grant

Concerning primary ice nuclei concentrations and water supersaturations in the atmosphere

- increasing IN concentrations by 100 times (to noted levels) in a microphysical model suggests that ice formation could deplete cloud water and prevent homogeneous freezing in maritime clouds with updrafts as large as 12 m s-1

Atmospheric Research 33, p. 151-168; 1994

A. Salam U. Lohmann B. Crenna G. Lesins P. Klages D. Rogers R. Irani A. MacGillivray M. Coffin

Ice Nucleation Studies of Mineral Dust Particles with a New Continuous Flow Diffusion Chamber

- montmorillonite is slightly more efficient as depositional ice nuclei than kaolinite - activation temperature of kaolinite dust particles in deposition mode: −22°C at 23% supersaturation with respect to ice - at a given temperature montmorillonite activated at a lower relative humidity as compared to kaolinite, even though the kaolinite particles are slightly larger

Aerosol Science and Technology 40, p. 134–143; 2006

K. Sassen Indirect climate forcing over the western US from Asian dust storms

- mineral dust as ice nuclei can lead to the formation of unusual warm cirrus ↔ dust effects phase of clouds → alter their radiative properties

Geophysical Research Letters 29, p. 1465; 2002 doi:10.1029/2001GL014051

C.H. Twohy S.M. Kreidenweis T. Eidhammer E.V. Browell A.J. Heymsfield A.R. Bansemer B.E. Anderson

Saharan dust particles nucleate droplets in eastern Atlantic clouds

- Saharan dust particles do commonly act as cloud condensation nuclei (CCN) in the eastern North Atlantic due to its slightly hygroscopic nature → dual nature of Saharan dust particles as CCN and ice nuclei → impact not only droplet size and albedo in small clouds, but ice formation in deep convective clouds - Since ice crystal number concentrations in most clouds are typically about three orders of magnitude smaller than droplet concentrations,


G. Chen S. Ismail P.J. DeMott S.C. Van Den Heever

changes in ice number concentration and size are possible as a result of dust entering droplets as CCN - changes in latent heating profiles in deep convection due to dust acting as IN are likely to change not only cloud microstructure and macrostructure but also cloud dynamics, with additional impacts on precipitation efficiency and storm lifetime

A. Welti F. Lüönd O. Stetzer U. Lohmann

Influence of particle size on the ice nucleating ability of mineral dusts

- deposition nucleation can be an important ice formation mechanism especially for cirrus clouds - the larger the particle diameter of a dust aerosol, the more efficient the ice formation in deposition mode (−30°C to −55°C) - size effect is less pronounced at lower temperatures - ice nucleation ability of a dust type depends on the surface properties of the dust particles - transition from deposition nucleation to condensation freezing has been observed for some dust particles when water saturation was reached → this is especially important for small particles as they require higher RHi to serve as IN at a certain temperature, compared to large particle sizes - Montmorillonite, kaolinite, illite and ATD: no superior nucleation ability of one mineral dust, similar contact angle at temperatures below −40°C, above −40°C the calculated contact angles for deposition nucleation are strongly temperature dependent


F. Zimmermann S. Weinbruch L. Schütz H. Hofmann M. Ebert K. Kandler A. Worringen

Ice nucleation properties of the most abundant mineral dust phases

- Onset relative humidities for ice formation (RHi) vary for the individual minerals between 107 and 117% → sufficiently low values to compete with homogeneous ice nucleation processes - temperature dependence of the onset relative humidity RHi is strongly dependent on mineralogy → Kaolinite, montmorillonite and hematite show a strong increase in RHi with decreasing temperature, RHi is almost constant for illite, albite, quartz and calcite - Illite and kaolinite are the most important minerals: high ice nucleation ability and common occurrence as major aerosol components; Hematite is also important owing to its high ice nucleation efficiency and its ubiquitous presence as surface coating on silicate grains


Impact on ocean authors title contents publication O. Aumont L. Bopp M. Schulz

What does temporal variability in aeolian dust deposition contribute to sea-surface iron and chlorophyll distributions?

- global model of ocean biogeochemistry forced with daily fields of dust deposition to investigate impact of variability of dust deposition (1996-2001) - dust deposition explains a large part of the temporal variability of surface iron in the tropical regions and in part of the subarctic Pacific - while dust deposition is dominated by daily events, its impact on surface iron is maximal on interannual timescales - largest fluctuations of surface iron produced by dust occur in oligotrophic regions where phytoplankton growth is not primarily controlled by iron availability → variability of surface chlorophyll induced by aerosol iron is predicted to be very small everywhere

Geophysical Research letters 35, L07607; 2008 doi: 10.1029/2007GL031131

A.R. Baker S.D. Kelly K.F. Biswas M. Witt T.D. Jickells

Atmospheric deposition of nutrients to the Atlantic Ocean

- examination of atmospheric dry deposition of iron, nitrogen and phosphorus, using samples collected during two meridional transects of the Atlantic Ocean -desert dust supplies excess iron to the water column - primary production promoted by aerosol nitrogen can be sufficient to consume all of the soluble aerosol iron input in some situations - Nitrogen fixation drives the ecosystem towards phosphorus limitation

Geophysical Research Letters 30; 2003 doi:10.1029/2003GL018518

J.K.B. Bishop R.E. Davis J.T. Sherman

Robotic Observations of Dust Storm Enhancement of Carbon Biomass in the North Pacific

- investigations with two autonomous robotic profiling floats (subarctic North Pacific, 10 April 2001, 8 months) → records of carbon biomass variability from surface to 1000 meters below surface - marine biological response to dust event (passage of Gobi desert dust cloud) → near doubling of biomass in the mixed layer over a 2-week period → temporal evolution of particulate organic carbon enhancement and an increase in chlorophyll use efficiency ↔ natural iron fertilization by the dust


S.C.Doney I. Lima R.A. Feely D.M. Glover K. Lindsay N. Mahowald J.K. Moore R. Wanninkhof

Mechanisms governing interannual variability in upper-oceaninorganic carbon system and air–sea CO2 fluxes: Physical climate and atmospheric dust

- presentation of a systematic global analysis of the magnitude and processes governing carbon system variability on subannual to decadal time-scales - mechanisms governing interannual variability in the upper-ocean carbon system and air–sea CO2 flux differ with region (major regions: Southern Ocean, tropical Indo-Pacific, and Northern Hemisphere temperate and subpolar latitudes) - Oceancirculation is the dominant underlying factor driving biogeochemical variability over most of the ocean - Variations in atmospheric iron deposition downwind of dust source regions generate substantial variability in ocean export production and air–sea CO2 flux in HNLC in the Southern Ocean, equatorial Pacific and subpolar North Pacific - reduced global dust deposition (beginning in the mid 1990s) generates increased air–sea CO2 outgassing in the Southern Ocean

Deep-Sea Research II, 56, p. 640-655; 2009 doi: 10.1016/j.dsr2.2008.12.006

R.A. Duce P.S. Liss J.T. Merrill E.L. Atlas P. Buat-Menard B.B. Hicks J.M. Miller J.M. Prospero R. Arimoto T.M. Church W. Ellis J.N. Galloway L. Hansen T.D. Jickells A.H. Knap K.H. Reinhardt B. Schneider A. Soudine J.J. Tokos S. Tsunogai R. Wollast M. Zhou

The atmospheric input of trace species to the world ocean

- atmosphere is pathway for the transport of many natural and pollutant materials from the continents to the ocean, for example important transport path for iron and nitrogen, which are important nutrients - the annual atmospheric fluxes of trace elements, mineral aerosol, nitrogen species, and synthetic organic compounds to the ocean are estimated and compared to the input via rivers (dry and wet deposition was although taken into charge) - on a global scale atmospheric inputs are generally equal to or greater than riverine inputs - for most species atmospheric input to the ocean is significantly greater in the northern hemisphere than in the southern hemisphere (for trace metals a factor of 5-10) - global atmospheric input dominates riverine input for Pb, Cd, and Zn - transport paths are roughly equal for Cu, Ni, As, and Fe - the global atmospheric input of synthetic organic species as HCH,PCBs, DDT, and HCB completely dominates their input via rivers

Global Biogeochemistry Cycles 5, 193; 1991

A.J. Gabric R.A. Cropp G.H. McTainsh B.M. Johnston H. Butler B. Tilbrook M. Keywood

Australian dust storms in 2002–2003 and their impact on Southern Ocean biogeochemistry

- 2002-2003 most active dust storm seasons in the last 40 years in Australia → large dust plumes advected over the adjacent SO → large scale natural dust fertilization in the Australian sector of the SO ↔ importance of dust derived nutrients in the marine carbon cycle of the SO - satellite and field data on surface chlorophyll indicate a significant biological response (unusually strong south of 50°S), associated with a strong CO2 drawdown → strong circumstantial evidence for a coupling between dust deposition, Fe delivery and biogeochemical response in the Australian sector of the SO

Global Biogeochemical Cycles 24, GB2005; 2010 doi:10.1029/2009GB003541

A.J. Gabric J.M. Shephard J.M. Knight G. Jones A.J. Trevena

Correlations between the satellite-derived seasonal cycles of phytoplankton biomass and aerosol optical depth in the Southern Ocean: Evidence for the influence of sea ice

- the production of DMS is related to atmospheric sulfate aerosols in the upper ocean (confirmed through shipboard measurements, global modelling) - correlation between surface chlorophyll (CHL) and AOD is analysed - mean CHL and AOD time series (1997-2004) are strongly coherent in the band between 50°S and 60°S (with absence in the SIZ south of 60°S) - interannual variability in CHL occurs in the SIZ related to the variability in sea-ice production during the previous winter - clear latitudinal difference in the cross correlation between CHL and AOD, with the AOD peak preceding the CHL bloom by up to 6 weeks in

Global Biogeochemical Cycles 19, GB4018, p. 10; 2005 doi: 10.1029/2005GB002546

the SIZ → substantial trace gas emissions (aerosol precursors) are being produced over the SIZ in spring (October–December) as sea ice melts

A.J. Gabric R. Simó R.A. Cropp A.C. Hirst J. Dachs

Modeling estimates of the global emission of dimethylsulfide under enhanced greenhouse conditions

- presentation of a modeling analysis of the global DMS response to simulate climate change (marine food-web model, an atmosphere-ocean general circulation model (GCM), and an empirical dimethylsulfide (DMS) algorithm used) - predict the DMS seawater concentration and the DMS sea-to-air flux in 10° latitude bands from 70°N to 70°S under contemporary and enhanced greenhouse conditions (changes to nutrients not explicitly included) - strong regional variability in the simulated DMS flux response, with little change in the tropics and major increases predicted at high latitudes → future increases in stratification in the polar oceans will play a critical role in the DMS cycle and climate change - ecological data indicate that planktonic populations can respond extremely sensitively and quickly to ocean variability

Global Biogeochemical Cycles 18, GB2014; 2004 doi: 10.1029/2003GB002183

A.J. Gabric R. Cropp G.P. Ayers G. McTainsh R. Braddock

Coupling between cycles of phytoplankton biomass and aerosol optical depth as derived from SeaWiFS time series in the Subantarctic Southern Ocean

- the Subantarctic Southern Ocean is a high-nutrient low-chlorophyll region → primary production is limited by deep mixing and the availability of iron (can be transported by Australian dust, particularly during the austral spring and summer) - coupling between satellite-derived (SeaWiFS) aerosol optical thickness and chlorophyll concentration in the upper ocean at monthly, weekly and daily timescales → episodic atmospheric delivery of iron is stimulating phytoplankton growth

Geophysical Research Letters 29, p. 1112-1116; 2002 doi: 10.1029/2001GL013545

C.O. Jo J.-Y. Lee K.-A. Park Y.H. Kim K.-R. Kim

Asian dust initiated early spring bloom in the northern East/ Japan Sea

- data for the TOMS aerosol index and SeaWiFS chlorophyll indicate that an early spring bloom in the northern East/Japan Sea can be initiated during the Asian dust event in association with precipitation (one month earlier than the bloom during non-dust event years) - normally initiated in this area as the surface mixed layer becomes shallower than critical depth, earlier bloom coincided with deepening of critical depth → supply of bio-available nutrients such as iron through wet deposition induces deepening of the critical depth, which results in an early initiation of the bloom


M.S. Johnson N. Meskhidze V.P. Kiliyanpilakkil S. Gassó

Understanding the transport of Patagonian dust and its influence on marine biological activity in the South Atlantic Ocean

- simulations (2009) indicate that the synoptic meteorological patterns of high and low pressure systems are largely accountable for dust transport trajectories over the SAO → South American dust plumes are elevated above the marine boundary layer → bulk concentration of mineral dust can quickly reach the HNLC waters of the SAO and Antarctica in ~3–4 days after emission from the source regions of Northern Patagonia - the effect of iron-laden mineral dust supply on surface ocean biomass is investigated by comparing predicted surface chlorophyll-a

Atmospheric Chemistry and Physics 11, p. 2487-2502; 2011 doi: 10.5194/acp-11-2487-2011

concentration ([Chl-a]) to remotely-sensed data - this study suggests that: (1) atmospheric fluxes of mineral dust from Patagonia are not likely to be the major source of bioavailable iron to ocean regions characterized by high primary productivity (2) Patagonian dust plumes could still influence background [Chl-a] in the South Atlantic sector of the SO

Y. Iwamoto K. Yumimoto M. Toratani A. Tsuda K. Miura I. Uno M. Uematsu

Biogeochemical implications of increased mineral particle concentrations in surface waters of the northwestern North Pacific during an Asian dust event

- mineral dust aerosols were scavenged by sea fog, and their deposition to the ocean increased the particle concentration in surface seawater - a general relationship for the solubility of iron from dust particles led to an estimate of 20 to 330 μg m-2 for the amount of bio-available iron delivered during the dust event (comparable to total dissolved iron added during an iron fertilization experiment in the northwestern North Pacific)

Geophysical Research Letters 38, L01604, p. 5; 2011 doi:10.1029/2010GL0459062011

N. Mahowald K. Lindsay D. Rothenberg S.C. Doney J.K. Moore P. Thornton J.T. Randerson C.D. Jones

Desert dust and anthropogenic aerosol interactions in the Community Climate System Model coupled-carbon-climate model

- the globally averaged climate and carbon is not significantly perturbed - the CCSM3.1 model has a slightly negative sensitivity to climate (i.e., more climate change means more carbon is taken up), due partly to the N-limitation in the land model, and partly due to a slow uptake by the oceans - the impact of aerosols onto the coupled-climate-carbon cycle may be largely explained by the globally averaged cooling from the aerosols, and is proportional to the climate impact on the carbon cycle - there are globally significant changes in carbon which are likely to be due to changes in regional climate driven by aerosols, or by changes in diffuse and direct radiation - inclusion of realistic desert dust cycling does significantly impact the ocean biogeochemistry in our simulations, in terms of the nitrogen fixation and the ocean productivity - having interactive dust and anthropogenic aerosols is as important or more important as changes in carbon dioxide and the resulting climate changes to the nitrogen cycle and productivity in our model - many changes to ocean biogeochemistry seem to occur due to physical forcing of climate by aerosols instead of purely from the addition of iron

Biogeosciences 8, p. 387–414; 2011 doi: 10.5194/bg-8-387-2011

E. Marañón A. Fernández B. Mouriño-Carballido S. Martínez-García E. Teira P. Cermeño P. Chouciño M. Huete-Ortega E. Fernández A. Calvo-Díaz

Degree of oligotrophy controls the response of microbial plankton to Saharan dust

- oligotrophy: lack of nutrients - different groups of phytoplankton and bacterioplankton responded differently to Saharan dust addition, although bulk abundance and biomass tended to remain unchanged - the relative increase in bacterial production, which was the dominant response to dust addition in ultraoligotrophic environments, became larger with increasing oligotrophy. In contrast, primary production, which was stimulated only in the least oligotrophic waters, became less responsive to dust as the ecosystem’s degree of oligotrophy increased → given the divergent consequences of a predominantly bacterial vs. phytoplanktonic response, dust inputs can, depending on the

Limnology and Oceanography 55(6), p. 2339–2352; 2010 doi: 10.4319/lo.2010.55.6.2339

X.A.G. Morán A. Bode E. Moreno-Ostos M.M. Varela M.D. Patey E.P. Achterberg

ecosystem’s degree of oligotrophy, stimulate or weaken biological CO2 drawdown

N. Meskhidze W.L. Chameides A. Nenes

Dust and pollution: A recipe for enhanced ocean fertilization?

- Fe solubilization in deliquesced mineral dust aerosols emanating from East Asia during the springtime outflow conditions is investigated with a Lagrangian box model of the gas and aqueous-phase chemistry (simulates scavenging, chemical reactions and dissolution of Fe-III oxides due to acid mobilization) - SO2 pollutant emissions are a potential source of acidity to advecting dust from East Asia - only plumes with relatively high initial SO2-to-dust ratios are capable of delivering significant amounts of bioavailable Fe to the NPO - large dust advection episodes should have insignificant dissolved iron fraction (DIF) as the amount of SO2 required to acidify such dust plumes is about an order of magnitude higher than what can typically be entrained in the plume during its advection - smaller dust plumes will generally have higher DIFs because they require lower amounts of SO2 and, even if such small plumes may not cause algae blooms, they could still be important sources of dissolved Fe to the NPO → future changes in SO2-pollutant emissions from East Asia may affect the productivity of the NPO


N. Meskhidze A. Nenes W.L. Chameides C. Luo N. Mahowald

Atlantic Southern Ocean productivity: Fertilization from above or below?

- two sources of Fe for the surface waters of the SO have been proposed: (1) oceanic input (upwelling of nutrient-rich water, lateral flows from continental margins) (2) atmospheric input - upwelling of nutrient-rich water is the predominant source of bioavailable Fe in the surface waters of the south Atlantic Ocean - acidification of aeolian dust may be required to solubilize the large fraction of mineral-iron and make it bioavailable


T. Oba T.F. Pedersen

Paleoclimatic Significance of Eolian Carbonates Supplied to the Japan Sea during the Last Glacial Maximum

- ∼40% of the total carbonates in the sediments at the last glacial maximum (LGM) are of eolian origin -> ∼2800 tons d−1 of eolian carbonates to the entire Japan Sea during the LGM -By increasing the alkalinity of North Pacific waters and by enhancing the biological pump the dust flux could have increased CO2 absorption by both the ocean and rain during the LGM

Paleoceanography 14(1), p. 34-41; 1999 doi:10.1029/98PA02507

L. Patara N. Pinardi C. Corselli E. Malinverno

Particle fluxes in the deep Eastern Mediterranean basins: the role of ocean vertical velocities

- the relationship between deep sedimentary fluxes and ocean current vertical velocities in an offshore area of the Ionian Sea (deepest basin of the Eastern Mediterranean Sea) is analysed (1999-May 2001) - tight coupling is observed between the upper and deep traps and the estimated particle sinking rates are more than 200mday−1

Biogeosciences 6, p. 333-348; 2009 doi: 10.5194/bg-6-333-2009

M. Tonani R. Santoleri S. Masina

→ direct effect of downward velocities in determining high sedimentation rates is excluded but upward velocities in the subsurface layers of the water column are positively correlated with deep particle fluxes → upwelling would produce an increase in upper ocean nutrient levels (stimulating primary production and grazing) a few weeks before an enhanced vertical flux is found in the sediment traps - tight coupling between surface and deep layers through particle aggregation mechanisms → fast sinking rates of organic material in the deep ocean are connected to both lithogenic and biological aggregation mechanisms that transfer particles rapidly in the deep water column - two emerging fast sinking mechanisms have been captured: 1. Pulses of primary production, triggered by upward current vertical velocities, followed by grazing and macrozooplankton-related biogenic flux that rapidly conveys the material in the deep ocean 2. Large Saharan dust events that fertilize the upper ocean and possibly contribute to aggregation of organic material, thus producing high sedimentation fluxes

A.G. Ramos A. Martel G.A. Codd E. Soler J. Coca A. Redondo L.F. Morrison J.S. Metcalf A. Ojeda S. Suárez M. Petit

Bloom of the marine diazotrophic cyanobacterium Trichodesmium erythraeum in the Northwest African Upwelling

- A T. erythraeum bloom such as that observed in August 2004 in the NW African Upwelling does not appear to have been recorded for the area previously → development due to the exceptionally warm weather and/or to the massive dust storms from the Sahara Desert observed in the NE Atlantic in August 2004

Marine Ecology progress series 301, p. 303-305; 2005 doi: 10.3354/meps301303

R.P. Singh A.K. Prasad V.K. Kayetha M. Kafatos

Enhancement of oceanic parameters associated with dust storms using satellite data

- using remote sensing data, an anomalous enhancement in the biological productivity of sea was observed in the Gulf of Oman: - during November to early December months of 1996–1999: attributed to cold sea surface temperature eddies - June–July–August and October–November–December months of 1997–2004: attributed to dust storms - the deposition of dust causes chlorophyll blooming within a period of 1–2 to up to 3–4 days - significant anomalous cooling of the ocean surface and relatively higher ocean wind speeds are also found during dust storms that may lead to favorable conditions for blooming

Journal of Geophysical Research 113; 2008 doi:10.1029/2008JC004815

A. Tagliabue L. Bopp O. Aumont

Ocean biogeochemistry exhibits contrasting responses to a large scale reduction in dust

- despite enforcing a climatically realistic dramatic reduction in the ocean deposition of aerosol Fe, we find that global NPP and FCO2 only decline by around 3% ↔ spatial redistribution of NPP that accompanies a decline in aeolian Fe input, as well as the lesser importance of aeolian Fe sources relative to continental shelf supply in the Pelagic

Biogeosciences 5, p. 11-24; 2008 doi: 10.5194/bg-5-11-2008

deposition Integration Scheme for Carbon and Ecosystem studies - dust deposition plays locally a role in sustaining diatom biomass in the ASO and could therefore be important in controlling the relative utilization of NO3 and Si(OH)4 and the associated marine food web; concomitant declines in denitrification stabilize the ocean DIN inventory (especially in the Pacific Ocean) and the excess NO3 that arises from reduced bacterial consumption can act as a negative feedback on N2 fixation - the denitrification– N2 fixation feedback is controlled by changes in nutrients and NPP/carbon export, and its efficiency depends on the degree and timescales of deep-water ventilation above denitrification sites ↔ compensating for any dust mediated decline - change in air-sea CO2 exchange between 1860 and 2100 is predominantly controlled by the change in atmospheric pCO2 and the decline in dust deposition reduces cumulative uptake by only 4%

W. Yuan J. Zhang

High correlations between Asian dust events and biological productivity in the western North Pacific

- investigation of dust events at 11 meteorological stations in China and sediment-trap fluxes at KNOT (the Kyodo North Pacific Ocean Time-series station) (12.1997-04.2000) - Al flux has significant correlations (0.66–0.78) with dust events at a water depth of 924 m → Badain Juran Desert region is a primary source of eolian dust to the western North Pacific - high correlations between the dust events and opal flux, and PD (pennate diatoms) → dust events stimulate biological productivity, providing nutrients via processes such as particle floating, adsorption and coprecipitation - evident correlation between opal flux at 924 m and GHA (geopotential height anomalies) at 850 hPa level with about a 10-day time lag → atmospheric cyclone activities might also contribute to ocean productivity


A Iron and iron solubility authors title contents publication A.R. Baker P.L. Croot

Atmospheric and marine controls on aerosol iron solubility in seawater

- fraction of atmospheric deposited iron plays a keyrole for the productivity in many open ocean regions - basic idea and interactions of solubility of iron in seawater is presented - experimental methods for the determination of iron solubility is discussed

Marine Chemistry 120, Issues 1-4, p. 4-13; 2008 doi: 10.1016/j.marchem.2008.09.003

A.R. Baker M. French K.L. Linge

Trends in aerosol nutrient solubility along a west–east transect of the Saharan dust plume

- examination of trends in the solubility of aerosol nutrients (Fe, P and Si) - solubilities were in the range 0.5–7.9% for Fe, 2.3–67% for P and 0.02–1.1% for Si - previous laboratory studies have suggested that aerosol Fe solubility might be enhanced by acid- and/or photo-chemistry during transport through the atmosphere


- The overall fraction of soluble Fe is unaffected by atmospheric processing on the timescale (5–10 days) → if (photo)chemical processing of aerosol Fe occurs, significant enhancement of Fe solubility requires longer than the 5–10 days associated with transport of Saharan dust across the tropical Atlantic Ocean - Aerosol P solubility does appear to increase during transport of Saharan dust across the Atlantic, but no relationship between SolP and acid species concentrations was observed

A.R. Baker T.D. Jickels

Mineral particle size as a control on aerosol iron solubility

- primary control on aerosol iron solubility is the surface area to volume ratio of mineral aerosol particles - this ratio changes during atmospheric transport (settling of larger particles) → increase of ratio → iron solubility is a inverse function of dust concentration on temporal and spatial scale

Geophysical Research Letters 33, L17608; 2006

S. Bonnet C. Guieu

Dissolution of atmospheric iron in seawater

- dissolution experiments of iron directly in seawater - dissolution processes are a function of the lability of iron in relation to the particle source, the particle size and adsorption processes - factors Controlling the Solubility: - scavenging - lability related to the origin of the aerosols - relation to particle size - pH (High iron solubilities were reached at pH 1 to 2) - study suggests that dissolution is lower for iron attached to Saharan particles than to anthropogenic particles (anthropogenic particles are finer than natural ones) - Saharan dust could influence primary production, especially during the season characterized by a stratified water column and low primary productivity → under these conditions atmosphere becomes the main pathway of macro and micronutrients to the surface mixed layer


N. Cassar M.L. Bender B.A. Barnett S. Fan W.J. Moxim H. Levy II B. Tilbrook

The Southern Ocean Biological Response to Aeolian Iron Deposition

- gross primary production and net community production (comparable to export production) are compared with model estimates of dissolved iron over large areas of the Southern Ocean → export production is proportional to modeled input of soluble iron in aerosols (fertilization due to addition of aerosol iron) - aerosol iron input particularly enhances gross primary production over the large area of the Southern Ocean downwind of dry continental areas → sequestration of carbon dioxide → may have been a major cause of the reduction of atmospheric CO2 during the ice ages


F. Chai M.-S. Jiang Y. Chao R.C. Dugdale F. Chavez R.T. Barber

Modeling responses of diatom productivity and biogenic silica export to iron enrichment in the equatorial Pacific Ocean

- Diatoms contribute to the initial increase of the total phytoplankton biomass due to iron enhancement, but decrease sharply after 10 days because of mesozooplankton grazing (grazing pressure prevents significant phytoplankton biomass accumulation) - increasing mesozooplankton grazing rate, the diatom increase due to iron addition stays at minimum level, but small phytoplankton tend to increase - larger size of the iron patch tends to produce a broader extent and

Global Biogeochemical Cycles 21, GB3S90; 2007 doi: 10.1029/2006GB002804

longer-lasting phytoplankton blooms - modeled depth-time distribution of sinking biogenic silica (BSi) indicates that it would take more than 30 days after iron injection to detect any significant BSi export out of the euphotic zone

K. V. Desboeufs R. Losno J. L. Colin

Factors influencing aerosol solubility during cloud processes

- Dissolution processes, leading to trace metals incorporation in aqueous phase, show beside others a great dependence on pH


R.A. Duce N.W. Tindale

The atmospheric transport of iron and its deposition in the ocean

- atmospheric deposition is the main iron supply, especially in remote oceans

Limnology and Oceanography 36(8), p. 1715-1726; 1991

D.J. Erickson III J.L. Hernandez P. Ginoux W.W. Gregg C. McClain J. Christian

Atmospheric iron delivery and surface ocean biological activity in the Southern Ocean and Patagonian region

- Surface chlorophyll and iron flux follow similar patterns, however chlorophyll may be displaced to different latitudes than where Fe input occurs due to meridional ocean transport (observation in Patagonia) - dust deposition of Fe may occur in one region and then ocean circulation moves the fertilized water mass away from the area of highest Fe flux → non-co-location of high Chl and high dust flux

Geophysical Research Letters 30(12), p. 1609-1613; 2003 doi: 10.1029/2003GL017241


Aeolian input of bioavailable iron to the ocean

- soluble Fe fraction increases with transport time from the source region and with the corresponding decrease in dust concentration → small Fe solubility and large dust deposition near the sources → large Fe solubility corresponding to smaller dust deposition distant from source regions - anthropogenic emissions of SO2 and NO should have caused a significant increase in hematite dissolution and soluble Fe input to the North Atlantic and North Pacific Oceans since the industrial revolution - re-mineralization of organic matter in the mixed layer does not lead to significant iron recycling


I.Y. Fung S.K. Meyn I. Tegen S.C. Doney J.G. John J.K. B. Bishop

Iron supply and demand in the upper ocean

- production in the high-nitrate lowchlorophyll (HNLC) regions is indeed limited by iron availability

Global Biogeochemical Cycles 14(1), p. 281-295; 2000

Y. Gao S. Fan J.L. Sarmiento

Aeolian iron input to the ocean through precipitation scavenging: A modeling perspective and its implication for natural iron fertilization in the ocean

- Model results show extremely low dust concentrations over the equatorial Pacific and Southern Ocean - wet deposition through precipitation scavenging accounts for ∼40% of the total deposition over the coastal oceans and ∼60% over the open ocean

Journal of Geophysical Research 108; 2003 doi:10.1029/2002JD002420

R.A. Glaccum J.M. Prospero

Saharan aerosols over the tropical North Atlantic mineralogy

- studies about the mineralogical composition of Saharan dust during transport over Atlantic Ocean - long range transport of dust induces a mineralogical splitting up by a preferential sedimentation of the coarse mode → increase of clay content → impacts on the iron solubility (increases during atmospheric

Marine Geology 37, p. 295-321; 1980

transport) - decrease of quartz relative part in favour of clay fraction due to faster sedimentation of quartz

J.L. Hand N.M. Mahowald Y. Chen R.L. Siefert C. Luo A. Subramaniam I. Fung

Estimates of atmospheric-processed soluble iron from observations and a global mineral aerosol model: Biogeochemical implications

- measurements of iron solubility - fine mode solubility is higher than coarse mode solubility - higher soluble fraction in fine mode is suggested because of a longer aerosol lifetime - aerosol interactions are important aspects of iron reduction processes


A. Ito Y. Feng

Role of dust alkalinity in acid mobilization of iron

- the impact of alkaline dust on the acid mobilization of iron is investigated - most alkaline dusts cannot be entirely consumed by acids during transport across the North Pacific Ocean - the iron solubility changes with mixing with alkaline carbonate minerals and subsequent atmospheric chemical processing - inclusion of alkaline dust in aqueous chemistry significantly limited the iron dissolution by inorganic acids in aerosol solution during the long-range transport - aluminosilicate-rich minerals might provide a highly-soluble aerosol iron due to the strong acid mobilization of iron - the deposition of soluble iron from smaller dust particles could be a dominant source of bioavailable iron over the eastern North Pacific Ocean


T.D. Jickels Z.S. An K.K. Andersen A.R. Baker G. Bergametti N. Brooks J.J. Cao P.W. Boyd R.A. Duce K.A. Hunter H. Kawahata N. Kubilay J. laRoche P.S. Liss N. Mahowald J.M. Prospero A.J. Ridgwell I. Tegen R. Torres

Global Iron Connections Between Desert Dust, Ocean Biogeochemistry, and Climate

- overview connection of dust and ocean biogeochemistry and its role within the climate system - schematic figure of the complexity of the connection of dust and global iron - the dominant external input of iron into the ocean is aeolian dust transport - iron is an essential nutrient for marine microorganisms - the dustsupply influences the oceanic primary production and CO2 uptake - given that the dustsupply is dependent on the climate change, there are many regional variations (climate feedback) → table of the effects of dust/iron on the ocean biogeochemistry - variation of iron fluxes can moreover change the phytoplankton (CO2 uptake, organic carbon export to deep water). It is a source of DMS, the only trace gas which is sensitive to iron and can influence the climate

Science 308; 2005

T.D. Jickels L.J. Spokes

Atmospheric Iron Inputs to the Oceans

- dust is removed out of the atmosphere by dry and wet deposition - processes are dependent on particle size - 30-95% of the removal is suggested to be wet deposition

The Biogeochemistry of Iron in Seawater, editor: D.R. Turner, K.A. Hunter, chapter 4, p. 85-121, Wiley, Chichester, UK; 2001

M.S. Johnson N. Meskhidze F. Solmon S. Gassó P.Y. Chuang D.M. Gaiero R.M. Yantosca S. Wu Y. Wang C. Carouge

Modeling dust and soluble iron deposition to the South Atlantic Ocean

- the global chemical transport model GEOS-Chem (+ dust-iron dissolution scheme) was used - dissolved iron fraction of mineral dust over the SAO was small (on average only accounting for 0.57% of total iron) ↔ low ambient concentrations of acidic trace gases available for mixing with dust plumes, not enough to overcome the alkalinity buffer of Patagonian dust and initiate considerable acid dissolution of mineral-iron - sol-Fe deposited to the SAO was largely controlled by the initial amount of sol-Fe at the source region → Patagonian dust should have a minor effect on biological productivity in the SAO

Journal of Geophysical Research 115, D15202, p. 13; 2010 doi: 10.1029/2009JD013311

E. Journet K. Desboeufs S. Caquineau J.L. Colin

Mineralogy as a critical factor of dust iron solubility

- laboratory measurements of solubility - results suggests that redox state of iron released in drop water is firstly controlled by dust mineralogy - iron oxides and hydroxides are composed more than 50% of iron → considered as main suppliers of dissolved iron resulting from dust - clays represent more than 96% of the total dissolved iron despite their low iron content but due to their high iron solubility - the input from (hydr)oxides dissolution is quasi-negligible


A. Kumar M.M. Sarin

Aerosol iron solubility in a semi-arid region: Temporal trend and impact of anthropogenic sources

- 1-yr chemical data for the fine mode (PM2.5) air-borne particulate matter in a semi-arid region of western India - inverse relationship between aerosol Fe and fractional Fe solubility (range: 0.06–16.1%) - increase in the solubility of iron, during wintertime, is marked by a uniform decrease in the mass fraction of mineral dust → advective transport of pollutants and Fe derived from combustion sources is one of the possible causes for the enhanced solubility of iron over a semi-arid region in western India

Tellus-B 62B, p. 125-132 ; 2010 doi: 10.1111/j.1600-0889.2009.00448

A.Kumar M.M. Sarin B. Srinivas

Aerosol iron solubility over Bay of Bengal: Role of anthropogenic sources and chemical processing

- chemical composition (involving water-soluble inorganic constituents, crustal elements and carbonaceous species) of size-segregated aerosols (PM10 and PM2.5), collected from the marine atmospheric boundary layer (MABL) of the Bay of Bengal (BoB) has been studied (27th Dec 08–28th Jan 09) → factors controlling the spatio-temporal variability in the fractional solubility of aerosol iron - significant linear relationship among fractional Fe solubility [WS-Fe (%)] and nss-SO4

2− over N-BoB (characterized by higher abundance of aerosol iron (FeA) and SO4

2−) provides evidence for the acid processing of mineral dust during atmospheric transport from Indo-Gangetic Plain - temporal shift in the winds exhibit enhanced fractional solubility of aerosol Fe associated with the lower abundance of dust and nss-SO4

2−

Marine Chemistry 121, p. 167-175; 2010 doi: 10.1016/j.marchem.2010.04.005

- observations suggest the dominance of combustion sources (biomass burning and fossil-fuel) in dictating the aerosol iron solubility over south Bay of Bengal → impact of the anthropogenic sources is also ascertained based on the covariance of WS-Fe with K+ and OC (organic carbon); as well as enrichment factor of heavy metals (Pb and Cd) associated with the outflow from south-east Asia

S. Lafon J. Rajot S.C. Alfaro A. Gaudichet

Quantification of iron oxides in desert aerosol

- natural samples from three main desert source areas were analysed: Sahel (Niger during local erosion events), Sahara (Niger during Harmattan events), Gobi desert (China) - the free-to-total iron ratio varied between 0.4 and 0.7 ↔ free-iron in aeolian dust is not directly proportional to the totaliron and depends on origin → total iron cannot be used directly to calculate dust light absorbing properties (light-absorption by mineral dust is controlled by the free-iron content)

Atmospheric Environment 38, p. 1211-1218; 2004

P.J. Lam J.K.B. Bishop

The continental margin is a key source of iron to the HNLC North Pacific Ocean

- FeP = tracer for the delivery of total Fe, also retains the memory of its source through its chemical speciation - calculations show that subsurface Fe delivery from the shelf is likely as important a source of bioavailable iron to the HNLC WSP gyre than dust - this subsurface supply of iron is shallow enough to be accessible to the surface through winter upwelling and vertical mixing (key source of bioavailable Fe to the HNLC North Pacific) - strong lateral advection of labile Mn and Fe from redox-mobilized labile sources at the continental shelf supplemented by a more variable source of Fe from the upper continental slope


P.J. Lam J.K.B. Bishop C.C. Henning M.A. Marcus G.A. Waychunas I.Y. Fung

Wintertime phytoplankton bloom in the subarctic Pacific supported by continental margin iron

- first evidence of the delivery and importance of iron from the continental margin and its arrival at OSP in the open HNLC subarctic Pacific - the entire continental shelf from California to the Aleutian Islands may be a source of additional iron in winter to the North Pacific → degree of iron limitation in the subarctic Pacific is not constant through the year and productivity can be boosted by different natural iron sources in different seasons - the wintertime delivery of bioavailable iron to the subarctic Pacific may address the paradox of why wintertime chlorophyll levels in subpolar HNLC regions are so high despite light limitation - the effects of shelf were found to be limited to coastal regions because the sedimentary iron was quickly scavenged out of the water column → the sensitivity of global ocean primary production to the shelf iron source was low - iron from shelf and continental sources is affecting the productivity of open ocean HNLC regions far (hundreds of kilometers) downstream


C. Luo N.M. Mahowald

Estimation of iron solubility from observations and a

- fine mode desert dust particles are observed to have twice the solubilities of coarse mode desert dust particles - labile iron fraction is twice as large as iron(II) fraction (= soluble=


N. Meskhidze Y. Chen L. Siefert A.R. Baker A.M. Johansen

global aerosol model bioavailable) - several different processes for conversion of Fe(III) to Fe(II) are simulated in a model, including 3 different sulfur based approaches, and one approach based on conversion by organic acids → distributions of iron solubility with much larger solublities → sulfur processing of dust probably occurs in clouds (cloud droplets may be acidic enough to process the iron)

doi:10.1029/2005JD006059

N.M. Mahowald A.R. Baker G. Bergametti N. Brooks R.A. Duce T.D. Jickells N. Kubilay J.M. Prospero I. Tegen

Atmospheric global dust cycle and iron inputs to the ocean

- iron solubility ranges from 0.01-80% and is extremely variable Global Biogeochemical Cycles 19, GB4025; 2005 doi:10.1029/2004GB002402

N.M. Mahowald S. Engelstaedter C. Luo A. Sealy P. Artaxo C. Benitez-Nelson S. Bonnet Y. Chen P.Y. Chuang D.D. Cohen F. Dulac B. Herut A.M. Johansen N. Kubilay R. Losno W. Maenhaut A. Paytan J.M. Prospero L.M. Shank R.L. Siefert

Atmospheric Iron Deposition: Global Distribution, Variability, and Human Perturbations

- review of atmospheric inputs of iron to the open ocean and modulation of ocean biogeochemistry - desert dust iron is estimated to represent 95% of the global atmospheric iron cycle, the remaining 5% due to combustion - largest deposition of iron occurs downwind of the main deserts of the globe (North Africa and the Middle East) - solubility of iron may be driven by both direct emissions of soluble combustion particles and atmospheric processing of insoluble iron in clouds - Humans may be increasing or decreasing atmospheric dust owing to land use and climate change (+/−50% possible) - Humans may be increasing soluble iron deposition to the oceans through increases in acidity of the atmosphere, which may increase atmospheric processing (+100% possible)

Annual Review of Marine Science 2009, 1, p. 245-278; 2009

J.K. Moore O. Braucher

Sedimentary and mineral dust sources of dissolved iron to the world ocean

- fluxes from continental margins and mineral dust deposition are key sources of dissolved iron to the oceans ↔ primary production, biological carbon export and nitrogen fixation (global scale) - calculation of the relative importance of dust deposition vs. sedimentation (on an annual basis)

Biogeosciences 5, p. 631–656; 2008 doi: 10.5194/bg-5-631-2008

J.K. Moore Iron cycling and nutrient- - a global marine ecosystem mixed-layer model is used to study iron cycling and nutrient-limitation patterns in surface waters of the world

Deep-Sea Research II 49, p. 463–507;

S.C. Doney D.M. Glover I.Y. Fung

limitation patterns in surface waters of the World Ocean

ocean - the model contains of a small phytoplankton size class whose growth can be limited by N, P, Fe, and/or light, a diatom class which can also be Si-limited, and a diazotroph phytoplankton class whose growth rates can be limited by P, Fe, and/or light - it includes a parameterization of calcification by phytoplankton - Nitrogen limits phytoplankton growth rates over less than half of the world ocean during summer months - export of biogenic carbon is dominated by the sinking particulate flux, but detrainment and turbulent mixing account for 30% of global carbon export - nitrate inputs to the surface layer can be equated with particulate carbon export needs to be expanded to include multiple limiting nutrients and modes of export

2002

W.J. Moxim S. Fan H. Levy II

The meteorological nature of variable soluble iron transport and deposition within the North Atlantic Ocean basin

- the northeast Atlantic receives its maximum seasonal SFeD during spring and experiences large yeartoyear variability (>45% up to 90%) associated with the NAO (strong NAO+ years can result in very large amounts of SFeD during times when synoptic scale cyclones coincide with outbreaks of Saharan dust) - summer produces the largest SFeD over the rest of the North Atlantic Ocean, with low yeartoyear variability (<30%) as a result of relatively steady anticyclonic flow around the Azores High - large surface concentrations of total Fe do not necessarily correspond with large SFeD as a result of the following: (1) Soluble Fe concentrations depend on the solubility of aerosol Fe, which subsequently depends on the history of chemical and cloud processing as well as the dry and wet removal during transport from North Africa to the Sargasso Sea (2) local occurrences of precipitation acting on the height profile of soluble Fe concentrations produce wet removal events that are usually greater than surface dry deposition


R. Paris K.V. Desboeufs P. Formenti S. Nava C. Chou

Chemical characterisation of iron in Dust and Biomass burning aerosols during AMMA-SOP0/DABEX: implication on iron solubility

- examination of two different aerosol samples: dust particles and biomass burning aerosol (BB) - chemical analysis and microscope observations show that iron (Fe) found in BB samples is mainly issued from dust particles externally mixed in the biomass burning layer - chemical analyses of samples show that solubilities determined for Fe in samples of African dust were significantly lower than the solubilities in aerosols of biomass burning → iron solubility in this source region is related to the character and origin of the aerosols themselves - mineral aerosols dominate above combustion sources by a factor above 30 at the global scale → the ratio of content of soluble iron between Dust and BB source should be around 30 - BB could be a large indirect source of mineral Fe due to the dust deposited on vegetation, but not significant compared to the Sahara as


a Fe source - phosphorous is produced by biomass burning - BB samples releases more phosphorous than the DUST samples → BB air masses could constitute a large supplier of P to the Ocean, but also for S and N, whereas inputs of soluble Fe and Si are dominated by dust deposition

P.K. Quinn T.S. Bates T.L. Miller D.J. Coffman J.E. Johnson J.M. Harris J.A. Ogren G. Forbes T.L. Anderson D.S. Covert M. J. Rood

Surface submicron aerosol chemical composition: What fraction is not sulfate?

- 9–45% of the submicrometre aerosol mass over the remote Pacific Ocean consists of species other than nss-SO4

2–, sea salt, NH4+, and MSA

Journal of Geophysical Research 105(D5), p. 6785–6806; 2000

Z. Shi S. Bonneville M.D. Krom K.S. Carslaw T.D. Jickells A.R. Baker L.G. Benning

Iron dissolution kinetics of mineral dust at low pH during simulated atmospheric processing

- Beijing dust and three size fractions of the Tibesti dust (<20 μm: PM20; <10 μm: PM10; and <2.5 μm: PM2.5) were dissolved at pH 1, 2 and/or 3 for up to 1000 h - in the first 10 min, all dust samples underwent an extremely fast Fe solubilisation - the Fe dissolution proceeded at a much slower rate before reaching a stable dissolution plateau - the dissolution rate constant k is independent of the source (Saharan or Asian) and the size (PM20, PM10 or PM2.5) of the dust but highly dependent on pH - the data demonstrated that dust/liquid ratio and pH are fundamental parameters controlling Fe dissolution kinetics in the dust


Z.B. Shi M.T. Woodhouse K.S. Carslaw M.D. Krom G.W. Mann A.R. Baker I. Savov G. Fones B. Brooks T.D. Jickells L.G. Benning

Minor effect of physical size sorting on iron solubility of transported mineral dust

Atmospheric Chemistry and Physics Discussions 11, p. 14309–14338; 2011

F. Solmon P.Y. Chuang N. Meskhidze

Acidic processing of mineral dust iron by anthropogenic compounds over the north

- Atmospheric processing of mineral aerosol by anthropogenic pollutants may be an important process by which insoluble iron can be transformed into soluble forms (= available to oceanic biota)


Y. Chen Pacific Ocean - production of soluble iron varies temporally and regionally depending on pollution-to-dust ratio (due to strong buffering by calcite) - ~30% to 70% of particulate soluble iron over the North Pacific Ocean basin can be attributed to atmospheric processing (especially chemical processing) - sensitivity tests suggest that doubling SO2 emissions can induce a significant increase (13% on average, up to 40% during specific events) in dissolved iron production and deposition to the remote Pacific - half of the primary productivity induced by iron deposition in a north Pacific high-nutrient low-chlorophyll region is estimated to be due to soluble iron derived from anthropogenic chemical processing of Asian aerosol

C. Theodosi Z. Markaki N. Mihalopoulos

Iron speciation, solubility and temporal variability in wet and dry deposition in the Eastern Mediterranean

- Iron solubility ranged from 27.2% for pH between 4 and 5 (polluted rainwater) to 0.5% for pH close to 8 (Sahara dust episodes), indicating that Fe solubility, and therefore Fe bioavailability to ecosystems, is enhanced in the presence of acidic species - Dissolved Reactive Iron (DSRFe) levels deposited in the Eastern Mediterranean Sea were sufficient to account for the dissolved iron levels in seawater → dissolved iron in the Mediterranean Sea could be exclusively attributed to atmospheric deposition - during summer and autumn less than 5% of the deposited dissolved Fe is required for phytoplankton growth

Marine Chemistry 120, p. 100-107; 2010 doi: 10.1016/j.marchem.2008.05.004

J.M. Velay R. Losno K.V. Desboeufs J.L. Colin

Atmospheric photochemistry influence on dust dissolution rate

- transition metals are involved both in catalytic and oxidoreduction reactions in the atmospheric cloud chemistry - impact of photochemistry on dust dissolution rate were investigated experimentally - for dissolution rate, only transition metals are affected by light

Geophysical Research Abstracts 8; 2006

H. Yang Y. Gao

Air-to-sea flux of soluble iron: is it driven more by HNO3 or SO2? – an examination in the light of dust aging

- coating of acidic gases changes dust from hydrophobic to hydrophilic (acid mobilization of Fe) - HNO3 makes a larger contribution to Fe mobilization than SO2 through dust aging in the atmosphere (HNO3 has a higher conversion rate) → 1. step to dissolve Fe - coating by HNO3 produces over 36% of soluble Fe fluxes compared to that by SO2 and sulfate - present trends in the emissions of precursors/sources: NOx: increase 4 times SO2: decrease slightly → relative contribution of HNO3 to Fe mobilization may get even larger → iron fertilization to oceanic biology caused by air pollution is going to continue - other factors besides HNO3, SO2 and sulfate: organic acids (form complexes with Fe), and the pH of the aerosol solution


R. Young K. Carder P. Betzer

Atmospheric iron inputs and primary productivity: phytoplankton responses in

- major pulses of dust from Asia was followed by major increases in primary production → chemical analyses of the atmospheric particles showed that they were iron-rich (10-15%) and, further, that if only a small proportion (e.g. 10%) of this iron dissolved in the euphotic zone

Global Biogeochemical Cycles 5, p. 119-134; 1991 doi: 10.1029/91GB00927

D. Costello R. Duce J. Ditullio N. Tindale E. Laws M. Uematsu J. Merrill R. Feely

the North Pacific - at all depths, systematic decreases in production followed the initial surge in production, indicating that the phytoplankton may have evolved from being iron-limited to being nitrogen-limited - mineral particles with settling velocities equivalent to those of 14 to 18-μm-diameter spherical quartz particles were the most likely source for the iron stimulating the increases in primary production

B Other nutrients authors title contents publication Q. Han J.K. Moore C. Zender C. Measures D. Hydes

Constraining oceanic dust deposition using surface ocean dissolved Al

- ocean basins maintain more distinct Al profiles than Fe profiles in the upper ocean, consistent with a weaker biological influence on Al than Fe -the Al distribution (maximum at the equatorial Atlantic, decrease towards higher latitudes, high concentrations: Mediterranean Sea, Arabic Sea, low concentrations: Pacific, Southern Ocean) reflects the combined effects of Al input from dust and Al removal by particle scavenging and biological uptake by diatoms - solubility of Al from Saharan dust is significantly lower than Al solubility from non-Saharan source regions -> solubility will vary regionally and as a function of air mass history and chemical transformation → Al is a good tracer for estimating dust deposition


S.E. Lindberg R.C. Harriss

Water and Acid Soluble Trace Metals in Atmospheric Particles

- solubility in seawater of Cd, Mn, Pb and Zn is inversely proportional to the particle size of the aerosols ↔ surface to volume ratio is inversely proportional to the size of the particles ↔ chemical composition of a given aerosol is not constant as a function of its size, the amount of H+ ions delivered in seawater is higher with small size particles - solubility increases with increasing frequency of atmospheric water vapor saturation during a sampling period

Journal of Geophysical Research 88(C9), p. 5091-5100; 1983 doi:10.1029/JC088iC09p05091

A. Nenes M.D. Krom N. Mihalopoulos P. Van Cappellen Z. Shi A. Bougiatioti P. Zarmpas B. Herut

Atmospheric acidification of mineral aerosols: a source of bioavailable phosphorus for the oceans

- deposition of atmospheric aerosols provides the major external source of phosphorus to surface waters ↔ primary productivity - but only a fraction of deposited aerosol phosphorus is watersoluble and available for uptake by phytoplankton - atmospheric acidification of aerosols is a prime mechanism producing soluble phosphorus from soil-derived minerals (expected where polluted and dust-laden air masses mix) → anthropogenic and natural acidic gas emissions may be a key regulator of ocean biogeochemistry

Atmospheric Chemistry and Physics Discussion 11, p. 6163-6185; 2011 doi: 10.5194/acpd-11-6163-2011

C. Theodosi The significance of - V, Cr, Fe and Pb were mainly associated with the particulate form (64–98%), whilst for Mn, Zn, Cu and Cd the soluble fraction represents

Marine Chemistry 120, p. 154-163;

Z. Markaki A. Tselepides N. Mihalopoulos

atmospheric inputs of soluble and particulate major and trace metals to the eastern Mediterranean seawater

60–70% of the total input → significance of atmospheric inputs to the biogeochemical cycling of trace elements - the solubility of all studied metals was found to decrease with increasing pH values and increasing dust mass - Cr, Mn and Cu fluxes were higher during the dry season compared to those measured during the wet season (other metals: opposite trend; Fe and Zn are removed almost equally by wet and dry deposition)

2010 doi: 10.1016/j.marchem.2010.02.003

Impact on hurricanes authors title contents publication J.P. Dunion C.S. Velden

The Impact of the Saharan air layer on Atlantic tropical cyclone activity

- investigation by GOES multispectral technique - the SAL appears to affect TC intensity change in the North Atlantic - the SAL appears to suppress Atlantic TC activity in three main ways: 1. introduces dry, stable air into the storm, which promotes convectively driven downdrafts in the TC 2. SAL’s midlevel easterly jet can dramatically enhance the local vertical wind shear 3. SAL enhances the preexisting trade wind inversion in the Atlantic, which acts to stabilize the environment

Bulletin of the American Meteorological Society 353; 2004 doi: 10.1175/BAMS-85-3-353

A.T. Evan J. Dunion J.A. Foley A.K. Heidinger C.S. Velden

New evidence for a relationship between Atlantic tropical cyclone activity and African dust outbreaks

- Atlantic tropical cyclone activity varies strongly over time, summertime dust transport over the North Atlantic also varies from year to year - strong relationship between interannual variations in North Atlantic tropical cyclone activity and atmospheric dust cover (satellite) is demonstrated (1982–2005) → robust link (instead of direct causal relationship) between tropical cyclone activity and dust transport over the Tropical Atlantic - mean dust coverage and tropical cyclone activity are strongly (inversely) correlated over the tropical North Atlantic - suggestion that these observed correlations may result from the effect of the Saharan Air Layer acting as a control on cyclone activity in the Tropical Atlantic, because dust is a good tracer for the Saharan Air Layer


A.T. Evan D.J. Vimont A.K. Heidinger J.P. Kossin R. Bennartz

The Role of Aerosols in the Evolution of Tropical North Atlantic Ocean Temperature Anomalies

- Observations and models demonstrate that northern tropical Atlantic surface temperatures are sensitive to regional changes in stratospheric volcanic and tropospheric mineral aerosols - 26-years of satellite data is used to drive a simple physical model for estimating the temperature response of the ocean mixed layer to changes in aerosol loadings - results suggest that 69% of the recent upward trend, and 67% of the detrended and 5-year low pass filtered variance, in northern tropical Atlantic Ocean temperatures is the mixed layer’s response to regional variability in aerosols

Sciencexpress 26, p. 1; 2009 doi: 10.1126/science.1167404

S.C. van den Heever G.G. Carrió W.R. Cotton W.C. Straka

The impacts of Saharan dust on Florida storm characteristics

- CCN, GCCN and ice forming nuclei (IFN) due to dust → effects on the nucleation of ice and liquid water → microphysical and dynamical characteristics of convective storm systems (accumulated precipitation and precipitation efficiencies of storms)

16th Conference on Planned and Inadvertent Weather Modification, Session 5, recent developments in understanding natural cloud processes and aerosol cloud interactions and how they might be modified-Part 1 (5.1); 2005

G.S. Jenkins A.S. Pratt A. Heymsfield

Possible linkages between Saharan dust and tropical cyclone rain band invigoration in the eastern Atlantic during NAMMA-06

- the Saharan Air Layer (SAL) influences the large-scale environment from West Africa to the western tropical North Atlantic → can create hostile thermodynamic and kinematic environmental conditions for tropical cyclogenesis and provides an infusion of cloud condensation and ice nuclei which can invigorate convection - these mechanisms may have been involved with the development of Tropical Storm (TS) Debby and Tropical Depression (TD) 8 (later Hurricane Helene) in 2006


W.K.M. Lau K.- M. Kim

How Nature Foiled the 2006 Hurricane Forecasts

- wrong forecasts because of the factor nature - data used for this study include SST, rainfall, cloud top temperature, water vapor from the Tropical Rainfall Measuring Mission (TRMM), and aerosol index (AI) from the Ozone Monitoring Instrument (OMI) on the satellite Aura

Eos 88(9), 27, p. 105-107; 2007

S. Nickovic C. Perez O. Jorba J.M. Baldasano

Atlantic tropical cyclones and Saharan dust: a simulation study

- the tropical cyclone Isaac (September 2000) was selected for first model experiments wit the DREAM dust model - a tropical cyclone system performs the dust transport more efficiently than that through a trade wind advection - dust was sucked up by the cyclone in the lower atmosphere and lifted by the cyclone convection into the higher troposphere - discrepancy of position of cyclone in the model after 7 days with and without radiation-dust interaction - > dust impacts may be significant

Geophysical Research Abstracts 10, EGU2008-A-06697; 2008 SRef-ID: 1607-7962/gra/EGU2008-A-06697

G.S. Rothman C. Chang T.E. Gill

Saharan air layer interaction with hurricane Claudette (2003)

- a diagnosis of the possible modulation of the atmospheric environment of Claudette (2003) due to Saharan dust is presented - focus on how the Saharan Air Layer (SAL) affects the early growth of the easterly wave and the intensity of Claudette in the later time period → heating rates because of SAL

26th Conference on Hurricanes and Tropical Meteorology, Poster Session 1 (P1.30); 2004

D. Rosenfeld A. Khain B. Lynn W.L. Woodley

Simulation of hurricane response to suppression of warm rain by sub-micron aerosols

- seeded simulation of Katrina resulted in the weakening of the hurricane surface winds compared to the ”non-seeded” simulated storm during the first 24 h within the entire tropical cyclone (TC) area compared to a control simulation without warm rain suppression - later, the seeding-induced evaporative cooling at the TC periphery led to a shrinking of the eye and hence to some increase in the wind within the small central area of the TC - the overall strength of the hurricane decreased in response to the suppressed warm rain at the periphery - in a simulation with warm rain suppression throughout the hurricane, the radius of the hurricane force winds was reduced by more than 42%, and although the diameter of the eye shrunk even further the maximum winds weakened


D. Sun K.M. Lau M. Kafatos

Contrasting the 2007 and 2005 hurricane seasons: Evidence of possible impacts of Saharan dry air

- 2007 hurricane activity in the Atlantic basin was near normal, although it was predicted to be much above-normal - dust aerosol loading during the early summer 2007 were found to be much stronger over the Atlantic Ocean compared to 2005


and dust on tropical cyclone activity in the Atlantic basin

- very few TCs, because: anomalous overturning circulation, warming in the middle atmosphere in the east dusty region, and cooling (>0.5_C) in the MDR, increasing moisture (from increased convection most likely) in the east and significant drying (subsidence) in the west in 2007 - the difference in westward penetration of the Saharan dry air and dust can be an important factor in contributing to the difference between the near- normal 2007 and 2006, and the very active 2005 hurricane seasons

V.M. Velasco H.J. Pérez-Peraza G. Velasco H. L.L. González

African Dust Influence on Atlantic Hurricane Activity and the Peculiar Behaviour of Category 5 Hurricanes

- influence of African dust on hurricanes is studied by applying wavelet analysis - strong decadal modulation on Category 5 hurricanes - annual modulation on all other categories of hurricanes - occurring mainly around the decadal minimum and in deep water areas of the Atlantic Ocean (hurricane eyes lowest pressure)

eprint arXiv:1003.4769; 2010

L. Wu Impact of Saharan air layer on hurricane peak intensity

- The Saharan air layer (SAL), which is associated with African dust outbreaks, forms as air moves across the Sahara Desert, containing substantial amounts of mineral dust - Sahel rainfall, SAL activity and hurricane peak intensity in the Atlantic basin are highly correlated → the long-term trend in hurricane peak intensity generally follows the Sahel rainfall and SAL activity - the decreasing trend in hurricane intensity by the mid-1980s was associated with the enhancing SAL activity and the severe drought in the Sahel - the study suggests that the SAL may act as a link between the summer African monsoon and Atlantic hurricane activity


H. Zhang G.M. McFarquhar W.R. Cotton Y. Deng

Direct and indirect impacts of Saharan dust acting as cloud condensation nuclei on tropical cyclone eyewall development

- by adding CCN within the initial environment, CCN directly affect the early eyewall evolution by varying distributions of latent heat, and hence trigger variations in dynamic and thermodynamic processes that ultimately modify eyewall intensity - adding CCN from the boundaries → more activated CCN → more cloud droplets with smaller diameters, but only in the rainbands - the amount of CCN that reached the eyewall, the total heat released by cloud diffusional growth, the major latent heating term in both the eyewall and rainbands, the storm intensity and the rainband intensity were not monotonically related to the input CCN conc. - a negative correlation of convective intensity in the eyewall with that in the rainbands was found - > the CCN indirectly affected the eyewall by modulating rainband development, but in a way that did not systematically depend on input CCN - only CCN activation show a simple relationship with input CCN - impact of dust acting as nucleating aerosols on TC development could be subjected to dry air in the SAL and strong wind shear


H. Zhang G.M. McFarquhar

Impacts of Saharan dust as CCN on the evolution of an

- increasing the background CCN concentration from 100 to 1000 and 2000 cm−3 in a layer between 1 and 5 km led to increases in averaged

Geophysical Research Letters 34, L14812; 2007

S.M. Saleeby W.R. Cotton

idealized tropical cyclone cloud droplet number concentration, and decreases in cloud droplet mean mass diameter → Dust in the SAL as CCN influenced the TC development by inducing changes in the hydrometeor properties, modifying the storm diabatic heating distribution and thermodynamic structure, and ultimately influencing the TC intensity through complex dynamical responses - simulated storm intensities differed by up to 22 hPa depending on CCN concentration - impact of CCN on storm intensity was sensitive to the background GCCN vertical profile and presumably other environmental factors

doi:10.1029/2007GL029876

H. Zhang I.N. Sokolik J.A. Curry

Impact of dust aerosols on Hurricane Helene’s early development through the deliquescent heterogeneous freezing mode

Atmospheric Chemistry and Physics Discussions 11, p. 14339–14381; 2011

Impact on biosphere authors title contents publication A.M. Farmer The effects of dust on

vegetation—a review - the effects of dust on crops, grasslands, heathlands, trees and woodlands, arctic bryophyte and lichen communities are identified → dust may affect photosynthesis, respiration, transpiration and allow the penetration of phytotoxic gaseous pollutants → generally there is decreased productivity

Environmental Pollution 79, Issue 1, p. 63-75 ; 1993

T. Hirano M. Kiyota I. Aiga

Physical effects of dust on leaf physiology of cucumber and kidney bean plants

- dust decreased stomatal conductance in the light, and increased it in the dark by plugging the stomata, when the stomata were open during dusting ↔ the effect was negligible when the stomata were closed during dusting - the effect was greater when dust of smaller particles was applied - the dust decreased the photosynthetic rate by shading the leaf surface (the dust of smaller particles had a greater shading effect) - the additional absorption of incident radiation by the dust increased the leaf temperature → change of the photosynthetic rate + increase of transpiration rate

Environmental Pollution 89, Issue 3, p. 255-261; 1995

Y. Ben-Ami I. Koren Y. Rudich P. Artaxo S.T. Martin M.O. Andreae

Transport of Saharan dust from the Bodélé Depression to the Amazon Basin: a case study

Atmospheric Chemistry and Physics Discussion 10, p. 4345-4372; 2010

C.S. Bristow K.A. Hudson-Edwards A. Chappell

Fertilizing the Amazon and equatorial Atlantic with West African dust

Geophysical Research Letters 37; 2010

Health aspects authors title contents publication P. Bennion R. Hubbard S. O’Hara G. Wiggs J. Wegerdt S. Lewis I. Small J. van der Meer R. Upshur

The impact of airborne dust on respiratory health in children living in the Aral Sea region

- prevalence of asthma is low in the Aral Sea area and appears to be unrelated to dust exposure - exposure to dust did not explain the main variations in lung function between geographical regions but high levels during the summer may have an adverse effect on lung function

International Journal of Epidemiology 36, p. 1103–1110; 2007 doi: 10.1093/ije/dym195

A.C. Comrie Climate Factors Influencing Coccidioidomycosis Seasonality and Outbreaks

- analyze linking climate and dust to fungal growth and dispersion (Arizona) - strong bimodal disease seasonality → dispersion-related conditions are important predictors of coccidioidomycosis incidence during fall, winter, and the arid foresummer - precipitation during the normally arid foresummer 1.5–2 years before the season of exposure is the dominant predictor of the disease in all seasons - 80% of the variance in coccidioidomycosis incidence can be explained

Environ Health Perspective 113, p. 688–692; 2005 doi: 10.1289/ehp.7786

A.G. Cook P. Weinstein J.A. Centeno

Health effects of natural dust Role of trace elements and compounds

- review of the health effects of trace elements carried in natural dusts of geologic or geochemical origin - principal elements and compounds reviewed are trace metals (including As, Hg, Cd, and Fe), radioactive elements, fluoride, silicates, natural asbestiform compounds, and alkali salts - pathways by which such agents affect human populations: carriage through water, air, soil, and the food chain - mechanisms of biotoxicity → acute and chronic consequences on health

Biological Trace Element Research 103(1), p. 1-15; 2005 doi: 10.1385/BTER:103:1:001

A. Echigo M. Hino T. Fukushima T. Mizuki M. Kamekura R. Usami

Endospores of halophilic bacteria of the family Bacillaceae isolated from non-saline Japanese soil may be transported by Kosa event (Asian dust storm)

- many halophilic bacteria that are able to grow in the presence of 20% NaCl are inhabiting in non-saline environments such as ordinary garden soils, yards, fields and roadways in an area surrounding Tokyo, Japan → Asian dust storms may possibly a source of the halophilic endospore at the seashore

Saline Systems 1(8); 2005 doi: 10.1186/1746-1448-1-8

B. Fubinia C. Otero Aréan

Chemical aspects of the toxicity of inhaled mineral dusts

- some kinds of mineral dusts (for example Silicosis, Asbestosis) can trigger a pathological response of the respiratory system by inhalation ↔ chemical (and physical) factors underlying mineral dust toxicity - pathogenic factors are reviewed, with a focus on the surface chemistry of mineral particles and interface phenomena

Chemical Society Reviews 28, p. 373–381; 1999

D.W. Griffin Atmospheric Movement of Microorganisms in Clouds of

- wide range of dust-borne pathogenic microorganisms mobilized into the atmosphere along with desert soils are capable of surviving long-

Clinical Microbiology Reviews 20(3), p. 459–477; 2007

Desert Dust and Implications for Human Health

range transport on a global scale (Bacillus anthracis, Yersinia pestis, Mycobacterium tuberculosis, Legionella pneumophila, Histoplasma capsulatum, influenza viruses, and rhinoviruses, etc.) - evidence of outbreaks of coccidiomycosis following dust storm exposure in America demonstrates risk

doi: 10.1128/CMR.00039-06

D.W. Griffin C.A. Kellogg V.H. Garrison J.T. Lisle T.C. Borden E.A. Shinn

Atmospheric microbiology in the northern Caribbean during African dust events

- results demonstrate that dust particles can serve as a vessel for the global dispersion of bacteria and fungi - air samples were collected in the northern Caribbean (2000-2001): non-dust conditions: 19 bacteria and 28 fungi (3,652 liters of air) dust conditions: 171 bacteria and 76 fungi (2,369 liters of air)

Aerobiologia 19, p. 143–157; 2003

D.W. Griffin C.A. Kellogg E.A. Shinn

Dust in the wind: Long range transport of dust in the atmosphere and its implications for global public and ecosystem health

- the article addresses the benefits and the potential hazards associated with exposure to particle fallout as clouds of desert dust traverse the globe

Global Change & Human Health 2(1); 2001

D.W. Griffin N. Kubilay M. Koc-ak M.A. Gray T.C. Borden E.A. Shinn

Airborne desert dust and aeromicrobiology over the Turkish Mediterranean coastline

- a statistically significant correlation was observed between an increase in the prevalence of microorganisms recovered from atmospheric samples on dust days, versus that observed on non-dust days → dust-borne microorganisms and other associated constituents (organic detritus, toxins, etc.) may play a significant role in the regional human and ecosystem health

Atmospheric Environment 41, p. 4050–4062; 2007 doi:10.1016/j.atmosenv.2007.01.023

T. Ichinose S. Yoshida K. Sadakane H. Takano R. Yanagisawa K. Inoue M. Nishikawa I. Mori H. Kawazato A. Yasuda T. Shibamoto

Effects of Asian Sand Dust, Arizona Sand Dust, Amorphous Silica and Aluminum Oxide on Allergic Inflammation in the Murine Lung

- experiments with mice - toxic materials adsorbed onto Asian SD, Arizona SD were inactivated by heat-treatment - Asian SD and Arizona SD exhibited an aggravating effect on OVA-associated eosinophilic lung inflammation. The enhancement may be mediated, at least partly, by the increased expression of IL-5 and MCP-3 in Arizona SD, and also by the modulated expression of IL-5 and MCP-3 in Asian SD. This effect may be due mainly to the presence of SiO2 in the sand dusts → atmospheric exposure to silica-carrying Asian SD may affect human health directly through allergic induction of respiratory stress

Inhalation Toxicology 20, p. 685–694; 2008

T.N. Kirkland J. Fierer

Coccidioidomycosis: A Reemerging Infectious Disease

- Coccidioides immitis, the primary pathogenic fungus that causes coccidioidomycosis, is most commonly found in the deserts of the southwestern United States and Central and South America → incidence can be correlated to climatic factors

Emerging Infectious Diseases 3(2); 1996

J. Liu D.L. Mauzerall L.W. Horowitz

Evaluating inter-continental transport of fine aerosols:(2) Global health impact

- the simulated annual mean population-weighted (P-W) concentrations of total PM2.5 (aerosols with diameter less than 2.5 mm) are highest in East Asia (30 mg m-3) and lowest in Australia (3.6 mg m-3) - dust is the dominant component of PM2.5 transported between continents

Atmospheric Environment; 2009 doi: 10.1016/j.atmosenv.2009.05.032

- We estimate global annual premature mortalities (for adults age 30 and up) due to inter-continental transport of PM2.5 to be nearly 380 thousand (K) in 2000 (half of these deaths occur in the Indian subcontinent) compared to 90 K deaths globally associated with exposure to foreign non-dust PM2.5

N. Middleton P. Yiallouros S. Kleanthous O. Kolokotroni J. Schwartz D.W. Dockery P. Demokritou P. Koutrakis

A 10-year time-series analysis of respiratory and cardiovascular morbidity in Nicosia, Cyprus: the effect of short-term changes in air pollution and dust storms

- Cyprus: dust blown from the Sahara resulting in extreme PM10 concentrations a few times a year - For every 10 µg/m3 increase in daily average PM10 concentrations, there was a 0.9% (95%CI: 0.6%, 1.2%) increase in all-cause and 1.2% (95%CI: -0.0%, 2.4%) increase in cardiovascular admissions - effect was observed only in the warm months - positive associations with levels of ozone were only observed the two days prior to admission (stronger for cardiovascular causes and independent of the effect of PM) - All-cause and cardiovascular admissions were 4.8% (95%CI: 0.7%, 9.0%) and 10.4% (95%CI: -4.7%, 27.9%) higher on dust storm days - increased risk of hospitalization on ozone and dust storm days (cardiovascular causes)

Environmental Health 7(39); 2008 doi: 10.1186/1476-069X-7-39

C. Mitsakou G. Kallos N. Papantoniou C. Spyrou S. Solomos M. Astitha C. Housiadas

Saharan dust levels in Greece and received inhalation doses

- the mean annual dust contribution to daily-averaged PM10 concentration values was found to be around or even greater than 10% in the urban areas throughout the years examined → natural dust transport may contribute by more than 20% to the annual number of exceedances (PM10 values greater than EU limits) - the inhalation dose from mineral dust particles was greater in the upper respiratory system (extrathoracic region) and less significant in the lungs, especially in the sensitive alveolar region - at dust episodes, the amounts of mineral dust deposited along the human lung are comparable to those received during exposure in heavily polluted urban or smoking areas


M. Naota T. Mukaiyama A. Shimada A. Yoshida M. Okajima T. Morita K. Inoue H. Takano

Pathological Study of Acute Pulmonary Toxicity Induced by Intratracheally Instilled Asian Sand Dust (Kosa)

- investigation of acute lung toxicity caused by Asian sand dust (mice experiment) → damage to the lung tissue through a direct physical effect + secondary released cytokines and oxidative stress generated in the lesion may be involved in the development of the acute lung toxicity

Toxicologic Pathology 38; 2010

P. Ozer M.B. Ould M. Laghdaf S. Ould

Estimation of air quality degradation due to Saharan dust at Nouakchott, Mauritania, from horizontal

- air pollution caused by large amounts of Total Suspended Particulates (TSP) and respiratory particulates or Particulate Matter less than 10μm in aerodynamic diameter (PM10) has numerous undesired consequences on human health

Water, Air & Soil Pollution 178, p. 79–87; 2007 doi: 10.1007/s11270-006-9152-8

M. Lemine J. Gassani

visibility data - the average annual concentration is far above air quality standards and estimated at 159μgm−3 for TSP and 108μgm−3 for PM10 → important public health hazard

L. Perez A. Tobias X. Querol N. Künzli J. Pey A. Alastuey M. Viana N. Valero M. González-Cabré J. Sunyera

Coarse Particles From Saharan Dust and Daily Mortality

- during Saharan dust days, a daily increase of 10 µg/m3 of PM10-2.5 increased daily mortality by 8.4% (95% confidence interval 1.5%–15.8%) compared with 1.4% (-0.8% to 3.4%) during non-Saharan dust days (P value for interaction =0.05) in Spain - in contrast, there was no increased risk of daily mortality for PM2.5 during Saharan dust days → coarse particles seem to be more hazardous during Saharan dust days, but differences in chemical composition did not explain the observations

Epidemiology 19(6); 2008

G.S. Plumlee S.A. Morman T.L. Ziegler

The Toxicological Geochemistry of Earth Materials: An Overview of Processes and the Interdisciplinary Methods Used to Understand Them

- brief overview of the myriad potential geochemical and biochemical processes that can occur when earth materials come into contact with body fluids via inhalation, ingestion, or percutaneous exposure routes - health effects are strongly influenced by the forms in which earth materials are delivered to the body (mineralogy; particle size and morphology; particle solubility, alkalinity, acidity; oxidation state of contained constituents; and others) - most earth materials are complex mixtures of many different components, each having a particular mix of bioreactivity, biosolubility, and biodurability characteristics → complex chemical interactions between the various earth material components and the body’s fluids may result

Reviews in Mineralogy & Geochemistry 64, p. 5-57; 2006

J.M. Prospero E. Blades G. Mathison R. Naidu

Interhemispheric transport of viable fungi and bacteria from Africa to the Caribbean with soil dust

- daily aerosol samples collected in trade winds at Barbados, West Indies, throughout 1996–1997 yielded significant concentrations of viable (culture-forming) bacteria and fungi only when African dust was present - air masses from the North Atlantic, North America, and Europe yielded no cultivable organisms → arid regions could be an important source for the long-range transport of viable microorganisms - microorganism and dust concentrations were unusually great in 1997, possibly in response to the strong El Nino → long-range transport of microorganisms might be responsive to climate variability in general

Aerobiologia 21, p. 1–19, Springer; 2005 doi: 10.1007/s10453-004-5872-7

S. Rodríguez X. Querol A. Alastuey G. Kallos O. Kakaliagou

Saharan dust contributions to PM10 and TSP levels in Southern and Eastern Spain

- most of the PM10 and TSP peak events are simultaneously recorded at monitoring stations up to 1000 km apart - high PM10 and TSP events occur when high-dust Saharan air masses are transported over the Iberian Peninsula - in the January–June period, this dust transport is mainly caused by cyclonic activity over the West or South of Portugal, whereas in the summer period this is induced by anticyclonic activity over the East or


Southeast Iberian Peninsula - most of the Saharan intrusions occur from May to September (63%) and in January and October - in rural areas in Northeast Spain the Saharan dust accounts for 4–7 annual daily exceedances of the forthcoming PM10-EU limit value, in rural areas in Southern Spain, the Saharan dust events accounts for 10–23 annual daily exceedances of the PM10 limit value (forthcoming EU standard: limit value cannot be exceeded more than 7 days per year)

M.C. Thomson

J. Djingarey M. Djingarey

Dust and epidemic meningitis in the Sahel: a public health and operational research perspective

- the potential climatic indicators and the climate information needs of relevance to the meningitis prevention and control community engaged in the African ‘meningitis belt’ is investigated

WMO/GEO Expert Meeting on an International Sand and Dust Storm Warning System, IOP Publishing, Conf. Series: Earth and Environmental Science 7; 2009

M.C. Thomson A.M. Molesworth M.H. Djingarey K.R. Yameogo F. Belanger L.E. Cuevas

Potential of environmental models to predict meningitis epidemics in Africa

- Meningococcal meningitis is a major public health problem in Africa - anomalies in annual meningitis incidence at district level were related to monthly climate anomalies → significant relationships were found for both estimates of rainfall and dust in the pre-, post- and epidemic season (strongest in savannah areas) → predicting epidemics of meningitis could be feasible

Tropical Medicine and International Health 11(6), p. 781-788; 2006

M. Viana C. Pérez X. Querol A. Alastueya S. Nickovic J.M. Baldasano

Spatial and temporal variability of PM levels and composition in a complex summer atmospheric scenario in Barcelona (NE Spain)

- summer atmospheric coastal dynamics exert a significant influence on the levels and composition of PM in NE Spain - dynamics are characterized by the absence of synoptic-scale air mass advections, the development of breeze circulations, enhanced photochemistry, local mineral dust resuspension and the occurrence of African dust outbreaks - breeze dynamics and thermal internal boundary layer formation seem to be the main meteorological drivers of the hourly evolution of PM levels - Levels of crystal components, secondary inorganic and carbon species are higher during the night, and only the marine aerosol content is higher during the day

Atmospheric Environment 39, p. 5343–5361; 2005

P. Yaka B. Sultan H. Broutin S. Janicot S. Philippon N. Fourquet

Relationships between climate and year-to-year variability in meningitis outbreaks: A case study in Burkina Faso and Niger

- Every year, West Africa is afflicted with Meningococcal Meningitis (MCM) disease outbreaks - the seasonal and spatial patterns of disease cases have been shown to be linked to climate - disease resurgence in Niger and in Burkina Faso is likely to be partly controlled by the winter climate through enhanced Harmattan winds

International Journal of Health Geographics 7(34); 2008 doi: 10.1186/1476-072X-7-34

D. Yin S. Nickovic B. Barbaris B. Chandy W.A. Sprigg

Modeling wind-blown desert dust in the southwestern United States for public health warning: A case study

- a model for simulating desert dust cycle was adapted and applied for a dust storm case in the southwest US, compared to satellite images, in situ surface PM2.5 and PM10 data, and visibility data → good performance of the model - PM2.5 peak hours were predicted very well (better than PM10 peak hours)

Atmospheric Environment 39, p. 6243–6254; 2005

- temporal varying trends (PM2.5 and PM10 concentrations) were similar to those observed

C.S. Zender J. Talamantes

Climate controls on valley fever incidence in Kern County, California

- Coccidioidomycosis (valley fever) is a systemic infection caused by inhalation of airborne spores from Coccidioides immitis, a soil-dwelling fungus found in the southwestern United States, parts of Mexico, and Central and South America - dust storms help disperse C. immitis → weak but statistically significant links between disease incidence and antecedent climate conditions - C. immitis tolerates hot, dry periods better than competing soil organisms, and, thrives during wet periods following droughts - nevertheless precipitation anomalies eight and twenty months antecedent explain only up to 4% of monthly variability in valley fever incidence (1980-2002) → relatively small correlation with climate suggests that the causes of valley fever could be largely anthropogenic - Arizona: seasonal climate predictors of valley fever are similar, but much stronger: precipitation explains up to 75% of incidence

International Journal of Biometeorology 50(3), p. 174–182; 2006 doi: 10.1007/s00484-005-0007-6

Impact on chemistry/chemical interactions authors title contents publication P. Bonasoni P. Cristofanelli F. Calzolari U. Bonafè F. Evangelisti A. Stohl S. Zauli Sajani R. van Dingenen T. Colombo Y. Balkanski

Aerosol-ozone correlations during dust transport episodes

- relationship between tropospheric ozone and mineral aerosol in the free troposphere of the Northern Mediterranean (June–December 2000) is investigated → a significant positive correlation between surface ozone and fine aerosol concentrations (Italy) and a strong anticorrelation between the concentrations of coarse particles and ozone has been found - high concentrations of coarse mineral aerosol in the atmosphere may lead to significant heterogeneous ozone destruction on the particle surface (affecting the ozone concentrations even in areas very far away from the dust mobilization regions) - it cannot be excluded that absorption by aerosol played a role in reducing photochemistry, thus producing a negative impact on ozone concentrations in the lower troposphere


A. Ooki M. Uematsu

Chemical interactions between mineral dust particles and acid gases during Asian dust events

- acid gas reactions during the passage from the source regions to the western North Pacific modify the chemical characteristics of Asian mineral dust particles as they pass through heavily industrial regions - Nitrate was the dominant acid substance associated with the mineral dust particles rather than non-sea-salt-(nss)-SO4 2− (concentration peaks of NO3 − and mineral dust particles were in the coarse mode range (D > 1.25 μm)) - HNO3 had reacted with mineral dust particles much more efficiently than SO2 had → high adsorption of HNO3 on mineral dust particles change their surface properties from hydrophobic to hygroscopic and form an efficient mechanism to remove nitrogen compounds to the ocean surface layer


K.D. Perry S.S. Cliff M.P. Jimenez-Cruz

Evidence for hygroscopic mineral dust particles from the Intercontinental Transport and Chemical Transformation Experiment

- the aluminum, silicon, and iron elemental mass distributions are a function of relative humidity → shift toward smaller sizes in the mass distribution by reduction of the relative humidity → indicates that the mineral dust transported from Asia to the west coast of the US is somewhat hygroscopic upon its arrival → hygroscopic nature of the aged mineral dust increase its ability to nucleate cloud droplets - measurements of transported Asian mineral dust (US, spring) show a strong correlation between the silicon and sulfur elemental mass concentrations → coarse mineral dust most likely accumulates sulfate coatings either near the source region or during transport across the Pacific Ocean

Journal of Geophysical Research 109, D23S28; 2004 doi: 10.1029/2004JD004979

N. Rastogi M.M. Sarin

Chemistry of aerosols over a semi-arid region: Evidence for acid neutralization by mineral dust

- evidence for quantitative neutralization of acidic constituents by mineral aerosols - ubiquitous alkaline-nature of rainfall events over this high dust region further attests to chemical data → regional-scale atmospheric transformation processes suggest the over estimation of negative radiative forcing (climate cooling) due to sulphate aerosols in the global climate models

Geophysical Research letters 33, L23815 GL027708; 2006 doi: 10.1029/2006GL027708

R.C. Sullivan S.A. Guazzotti D.A. Sodeman Y. Tang G.R. Carmichael K.A. Prather

Mineral dust is a sink for chlorine in the marine boundary layer

- dust particles providing a surface on which heterogeneous reactions can occur → uptake of soluble species on dust alters the physical, chemical, and optical properties and the overall ability of dust to act as cloud condensation and ice nuclei - chloride in dust occurs as the result of internal mixtures of sea-salt and dust particles, formed by cloud processing, but also mineral dust can directly uptake chlorine via heterogeneous reaction with HCl(g) → up to 65±4% of the dust particles contained chlorine due to this heterogeneous reaction → change of pH and hygroscopic properties of the dust → can influence the budgets of other reactive gases


D. Trochkine Y. Iwasaka A. Matsuki M. Yamada Y. Kim T. Nagatani D. Zhang G. Shi Z. Shen

Mineral aerosol particles collected in Dunhuang, China, and their comparison with chemically modified particles collected over Japan

- Approximately 40–45% of mineral particles mixed internally with sulphate during their transport in the troposphere

Journal of Geophysical Research 108(D23), p. 8642; 2003 doi: 10.1029/2002JD003268

Y. Zhang G.R. Carmichael

The Role of Mineral Aerosol in Tropospheric Chemistry in East Asia—A Model Study

- dust has a significant influence on tropospheric trace gases and the total oxidation capacity by serving as a surface sink for gaseous species and providing reaction sites for heterogeneous oxidation of absorbed species - observation: high nitrate and sulfate on dust and anticorrelation between O3 and dust in East Asia - the decrease in solar actinic flux and the surface uptake of O3 and its precursors were found to be important to the total O3 decrease - Size, surface area, and mass concentration of dust were shown to be important parameters, with particles in the size range of 1.5–10.0 μm contributing most significantly to their formations

Journal of Applied Meteorology and Climatology 38, p. 353–366; 1999

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