Gerrit de Leeuw1,2,3, Larisa Sogacheva1, Pekka Kolmonen1, Anu-Maija Sundström2,

Edith Rodriguez1

1 FMI, Climate Change Unit, Helsinki, Finland

2 Univ. of Helsinki, Dept. of Physics, Helsinki, Finland

3 TNO, Utrecht, Netherlands

Retrieval of aerosol properties using AATSR

ATSR-2 (ERS-2) : 1995 – 2002+AATSR (ENVISAT) : 2002 – 2009+ SLST (Sentinel 3) : 2013 –

> 0.555, 0.659, 0.865, 1.6, 3.7, 11, 12 μm> 1 x 1 km2

> 500 km swath (global in ~5 days)

> 0.555, 0.659, 0.865, 1.6, 3.7, 11, 12 μm> 1 x 1 km2

> 500 km swath (global in ~5 days)

Aerosols/types; clouds

‘High’ resolution

Along Track Scanning Radiometer - ATSR

•Sun synchronous

•Equator overpass time 10:00

•Swath 500km

• Spectral Channels• IR: 1.6, 3.7, 10.85, and 12 μm • VIS: 0.555, 0.67, and 0.865 μm

• Spatial resolution 1 x 1 km

• Two viewing angles allow to account for surface effects on TOA radiation

• Over land the dual view aerosol retrieval algorithm (ADV) is used

• AATSR has two viewing angles; forward at 55° , and nadir

Basic concepts of the DV-algorithm

• TOA-reflectance for an underlying Lambertian surface

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TOAf

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• Spectral and Directional information of ATSR-2

• Shape of the BRDF independent of the wavelength

• Effects of aerosols small at 1.6 µm

• Bi-modal aerosol model

• Veefkind et al., GRL vol 25, no. 16, 3135-3138, 1998

00cos F

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Schematic representation of DV- and SV- algorithms

Satellite observation:•Instrument characteristics•Calibration•Cloud and surface effects

Radiative Transfer Model : DAK (Double Adding KNMI)•Optical properties aerosol•Meteorology

Actual retrieval

SV:Over ocean

Crucial steps in aerosol retrieval• Cloud screening: any residual cloud in a scene

results in high AOD

• Surface contributions:

• Eliminate: multiple view

• Dark surface over ocean, with Ocean surface reflectance model

• Radiative transfer model

• Compare modeled reflectance at top of atmosphere with measurement

• ’Best fit’ provides desired aerosol parameters

Test for August 10th 2004Comparison with MODIS

Cloud Protocol : 4 tests•BT12µm

• R659

• R865nm/R659

• BT12µm – BT11µm Not always used Agreement: 83.03 % Disagreement: 12.05 % Non conclusive: 4.91 %

AATSR CLOUD MASK

CLEAR

CLOUD

AATSR CLOUD MASK

CLEAR

Cloud Screening

Aerosol models in ADV:• based on AERONET

observations • Dubovik et al. 2002: Variability of

absorption and optical properties of key aerosol types observed in worldwide locations. J ATMOS SCI, 59 (3): 590-608.

• Robles-Gonzalez et al. 2002, Aerosol properties over the Indian Ocean Experiment (INDOEX) campaign area retrieved from ATSR-2, J. Geophys. Res., 111, D15205, doi:10.1029/2005JD006184.

• Levy et al. 2007: Global aerosol optical properties and application to Moderate Resolution Imaging Spectroradiometer aerosol retrieval over land. J. Geophys.

Res., 112, D13210.

ADV Aerosol Remote Sensing Applications

Europe: 2003, 2006, 2008

2003, yearly avarage

(Pekka Kolmonen)

ADV Aerosol Remote Sensing Applications

Europe: forest fires Iberian Peninsula, 11 August 2003

(Anu-Maija Sundström)

ADV Aerosol Remote Sensing Applications

Europe: focus on Po Valley (TEMIS)

2003, yearly average

(Pekka Kolmonen)

2003, July-August average

0.9

ADV Aerosol Remote Sensing Applications

Europe: clean air over Finland

02 May 2006

(Larisa Sogacheva)

04 June 2008

ADV Aerosol Remote Sensing Applications

Focus on China

0.55 m; 25 July 2008Variability (0.55 m):

March 2008

(Anu-Maija Sundström)

3.0

ADV Aerosol Remote Sensing ApplicationsFocus on China

(Anu-Maija Sundström)

ADV Aerosol Remote Sensing ApplicationsFocus on China

(Anu-Maija Sundström)

Single overpass: 19Oct2008 Zoom over Beijing area

3

Aerosol Remote Sensing Applications

Po Valley

Regional: Europe

Smoke Iberian Peninsula

Finland:clean air N

ote scales

0.7

0.2

1.8

0.7

China, Beijing

CONCLUSION: ADV works for very low AOD over Finland (~0.05) to very high AOD over China (~3)

Data sets• Available:

• Europe 2003, 2006, 2008

• Zoom on Po-Valley

• China 8 months in 2008, more to come

• Amazone: work in progress

• Africa, India, Brazil, Beijing: EUCAARI Development Countries: work in progress

• Ocean: AMARSI algo tested (AATSR / MERIS) and ready for use

• Global: MACC: 2 years, work in progress

• All AATSR data received on LTO tape (7/2002 – 4/2009)

Conclusions• The AATSR Dual view algorithms works over land in a variety of

conditions• No a priori info on surface needed, but could improve the results• Aerosol models through LUT approach; could be improved • Some reasonable results have been obtained over the desert

over the UAE (bright surface), but little or no dust• Cloud screening reasonable, but may be further improved • Dust detection often fails, a dust detection algorithm developed

for SEVIRI over ocean (Bennouna et al., 2009, in press) is tested for AATSR

SEVIRI: Dust Retrieval over Ocean

Bennouna et al., 2009, JGR Atmospheres, in press

Conclusions• AATSR data archive (7/2002-4/2009) received and read• NRT under development:

• Uses rolling archive • Long time series: ATSR-2 – AATSR – SLSTA

(1995 – present .. 2013 >)• Problems:

• AATSR swath limits coverage• Clouds• Snow

Use of AATSR data in GLOBemissions• Data assimilation: data interval too long (3 days at

mid latitudes or more when clouds)

• Hotspot detection

• Localized sources, such as:

• Forest fire emissions

• Power plants

• (needed for inventories)

• Inversion?

• Advantage with respect to ’operational’ products:

• Choice of pixel size (1x1 km2 or larger)

• Selection appropriate aerosol model