Retrieval of Aerosol Properties from Space

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Retrieval of Aerosol Properties from Space
Gerrit de Leeuw, Cristina Robles Gonzalez,
Jolanta Kusmierczyk-Michulec, Rob Decae
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Objectives

• Retrieve aerosol properties using data from
  spectrometers aboard satellites
• Spatial resolution ? 1 x 1 km2
• Local, regional or global coverage
• Aerosol Optical Depth (AOD)
• Ångström parameter
• Aerosol types and mixing ratio
• Assimilation of the results in chemistry
  transport models
• constrain the models
• improve the retrieval
• Applications
• Climate
• Weather forecasting
• Air quality/Chemical weather
• Atmospheric correction

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Along Track Scanning Radiometer 2

• Radiometer on ERS-2
• Seven Bands, four in VIS/NIR (0.555, 0.659,
  0.865 and 1.6 ?m)
• Swath Width 500 km
• Spatial Resolution 1x1 km2
• Dual-View capability

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ATSR-2 Dual-View Algorithm

• 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

Accuracy 0.06 0.05 at 0.659?m
Single view algorithm (over water) Accuracy
0.04 0.01
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Aerosol Optical Depth over Europe
Robles-Gonzalez et al., 2000.
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ATSR-2 data assimilation in LOTOS
(Builtjes et al., 2000)
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ATSR-2 algorithmsRecent advancements

• Automated cloud detection over land following
  criteria of Koelemeijer and Stammes 1999
• The old algorithm had two aerosol types
• Marine
• Contintental
• Distributed in the vertical following the BL
  structure
• Other aerosol types were added
• dust, black carbon, biomass aerosol, organic,
  sulphate, nitrate, sea salt
• Vertical distribution according to climatology
  and available data
• Aerosol mixtures, chosen from climatological and
  other data sets
• LUTs prepared using radiative transport model
  (DAK Stammes et al., 1989)

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Comparison with AATS data (SAFARI 2000)
Schmid et al., JGR 2002, in press
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Comparison with AATS data (SAFARI 2000)
Schmid et al., JGR 2002, in press
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INDOEX 1999Combined dual view (over land) and
single view (over water)
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INDOEX 1999Comparison with AERONET sun
photometer data
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INDOEX 1999Comparison with AERONET sun
photometer data
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INDOEX 1999Ångström parameters
Polluted
Marine
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INDOEX 1999Mixing ratio sea spray and ind.
polluted mixture
Polluted
Sea Spray
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ATSR-2 retrievals assimilated in TM3
Verver et al. 2002
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Initialisation of retrieval using model results
as first estimate for the aerosol type
Verver et al. 2002
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Instruments used at TNO-FEL

• ATSR-2 (ESR-2)
• dual view over land
• single view over sea
• GOME (ERS-2)
• UV method
• AATSR (ENVISAT)
• similar to ATSR-2
• SCIAMACHY (ENVISAT)
• UV method over land
• IR over water
• OMI (AURA)
• UV method
• MSG/SEVIRI

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CONCLUSION

• Algorithms for several instruments are available,
  for retrieval over water and over land
• The ATSR-2 algorithm has been extended with
  automated cloud screening over land and more
  aerosol types
• Comparison with AATS (SAFARI) and AERONET
• Assimilation in chemistry transport models
• LOTOS PM2.5
• TM3 INDOEX area
• The assimilation in TM3 is a pre-study for the
  application of SCIAMACHY data