Bridging Scales in Atmospheric Chemistry:from satellite to molecule

Queen’s UniversityJanuary 30, 2013

Colette L. HealdMaria Val Martin, David A. Ridley

Atmospheric Composition is Linked to Major Environmental Issues

AIR QUALITY / HEALTH VISIBILITY ACID RAIN

CROP DAMAGE OZONE LAYERTOXIC

ACCUMULATION

CLIMATE

FERTILIZATION

Scientific Challenge: Characterize the Emissions and Transformations Well Enough to Estimate Impacts

Evolution of Pollution(Chemistry + Transport)

Emissions1. Anthropogenic pollution2. Natural/biogenic

Air Quality Impacts:1. Visibility

2. Health 3. Agriculture

Climate Forcing: 1. GHG warming2. Aerosol warming/cooling

What’s Really the Problem?Diversity of Scales at Play, Coupled Physical & Chemical Processes

[ ]( [ ])X X X X

XE X P L D

t

U

local change in concentration

with time

transport(flux divergence;U is wind vector)

chemical production and loss(depends on concentrations of other species)

emissiondeposition

Inflow Fin Outflow Fout

X

E

EmissionDeposition

D

Chemicalproduction

P L

Chemicalloss

1 box model Global Model

What Is An Aerosol?(also called particulate matter or PM)

Particles in the atmosphere come from both natural and pollution sources, have a range sizes, properties and chemical complexity. They can be emitted directly (e.g. soot from diesel

engine) or formed chemically (e.g. sulfate formed down-wind of a power plant)

By 2030, PM will be the leading

environmental cause of premature death (3.6 million

deaths/year) [OECD, 2012]

Scatter/absorb radiation and critical to cloud formation. The leading cause of

uncertainty in climate forcing

[IPCC, 2007]

Challenge: Heterogeneity of Atmospheric Composition

GEOS-5 10 km aerosol model

http://www.nasa.gov/multimedia/imagegallery/image_feature_2393.html

Many first order problems with atmospheric species (how much? what sources?) challenging to address because of the short lifetimes and varying properties of gases/particles in the

atmosphere.

Solution: Satellite Observations!Otherwise observation network for tropospheric composition is sparse

Tropopause (8-18 km)

TROPOSPHERE

STRATOSPHERE

aircraft

22 km

Surface sites ships, islands, buoys

Satellites

• solar backscatter• atmospheric emission• occultation• lidar

sonde

Remote Sensing: The Classic Inverse Problem

?

Given observed spectra, what is the atmospheric state that produced it?

Problems:1.Non-uniqueness of solution (need to apply a priori information)2.Discreteness of measurements of a smoothly varying function

3.Instability of the solution due to errors in the observations

The whole field of retrieval theory/practice!

Sink: Oxidation by OHCOLifetime = 1-2 months

CH4

NMHC

OH

Fossil FuelsBiomass Burning Biofuels

LARGE uncertainties on bottom-up emission inventories

“Simple” chemical evolution

Carbon Monoxide: Tracer of Pollution

Carbon Monoxide Transpacific Transport Seen From Space

Asian pollutionexported via coldfront

Plume encounters ablocking H PressureSystem and splits

Elevated CO reachesNorth AmericaSouthern branch at lowlatitudes produces O3

Feb 23

Feb 24

Feb 25

Feb 26

Feb 27

MOPITT GEOS-Chem x Avgker GEOS-Chem

Total column CO

[Heald et al., 2003b]Four such events observed in spring 2001.

Integration of Aircraft, Satellite and Models to Quantify Carbon Monoxide Sources from Asia

OBSERVATIONSEMISSIONS

Forward Model(GEOS-Chem CTM)

Anthropogenic CO [Streets et al., 2003 and Logan & Yevich]

Biomass Burning CO[Heald et al., 2003a]

MOPITT CO

TRACE-PAircraft CO

Inverse Model(Bayesian linear)

Anthropogenic emissions underestimated (China = 39% too low)Biomass burning emissions too high (SE Asia = 50% too high)

[Heald et al., 2004]

Dust From North Africa: Impacting Air Quality and Biospheric Productivity Down-Wind

More than half of dust emitted globally from N. Africa

TOMS: June 13-21, 2001

summer

winter/spring

Miami (1989-1997)[Prospero et al., 1999]

[Prospero et al., 1981]

French Guiana (1978-1979)

Observation-poor so rely on models to estimate this. Satellites can provide much needed reality-check!

Using Satellite Observations to Test Simulation of Dust

(1) Improve model simulation near source with better representation of particle size(2) Model removes too much dust during transport in winter. Reveals that deposition

estimates to Amazon are likely a lower limit[Ridley et al., 2012]

Seasonally averaged aerosol

along Atlantic outflow transects

Winter

Summer

Improve dust particle

sizes

Using Satellite Observations to Constrain the Global Budget of Organic Aerosol

[Heald et al., 2010b]

MISR AOD

Simulated AOD from

OTHER aerosol

Residual =

Organic Aerosol

Satellite measurements indicate that total OA source is capped at 150 TgC/yr (at lower end

of previous estimate)This is still 3 times what is currently included

in models.

TgC/yrSummer

???

2012: Most Destructive Fires in Colorado History, with Air Quality Implications

High Park Fire (June 2012)

Waldo Canyon Fire (July 2012)

Preliminary hourly/daily PM2.5 and Satellite AOD over 10 Colorado sites

Many local exceedances of daily PM2.5 standard (over 100 µg/m3 measured in Fort Collins!)Satellite aerosol observations (AOD) track surface PM observations

EPA daily PM2.5 standard

2012

Decadal Satellite Record Shows Large Aerosol Anomalies Associated with Both Local and Transported Smoke

June 2002

[val Martin et al., in prep]

MODIS Terra AOD anomalies

August 2012

Hayman Fire

High Park andWaldo Fires

AZ Wallow Fire(2011)

MT, WY, ID, WA FiresAZ, CA

Fires

CA Station Fire(2009)

Atmospheric Ammonia: A Source of Particulate Matter and Emissions on the Rise…

AnimalsAgriculture

NH3 emissions major source of fixed N

atmospheric acids (H2SO4, HNO3)

Haber-Bosch Process (industrial production of NH3 fertilizer) has

dramatically increased global food production.

…degrading air quality?now and in the future?

Atmospheric NH3 is difficult to measure

[Erisman et al., 2008]

+ =

Insight Into Ammonia Sources over the US

New satellite measurements offer

unprecedented monitoring of NH3.

Comparison with model reveals springtime underestimate of emissions in the

Midwest and year-round underestimate in the

Central Valley of California (AQ exceedances).

[Heald et al., 2012]

Atmospheric chemistry central to several environmental issues (air quality, climate, ecosystem health, etc)

Atmospheric composition is highly heterogeneous.

Satellite observations providing unprecedented constraints on emissions, transport and budgets of gases and aerosols in the atmosphere.

(Eng Phys was surprisingly good preparation for all this!)

Funding Acknowledgements: