Aerosol absorption: From pollution, dust, and biomass burning

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Aerosol absorption From pollution, dust, and
biomass burning

• Mian Chin and Thomas Diehl plus
• AERONET Team OMI Team for data
• Giovanni for OMI data disseminating

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Introduction

• Aerosol absorption plays several important roles
  in the earth system
• It contributes to global warming (Hansen,
  Jacobson, etc.)
• It modifies the atmospheric heating, thus
  atmospheric dynamics and atmospheric hydrological
  cycles (Menon, Lau etc.)
• It can change the cloud properties (Kaufman,
  Koren, etc.)
• It affects atmospheric photochemistry (Dickerson,
  Martin, etc.)
• AND, IT LINKS TO AIR QUALITY PROPORTIONAL TO
  BLACK CARBON OVER POLLUTED REGIONS AND BIOMASS
  BURNING CARBONACEOUS AEROSOLS, AND TO DUST
• We compare absorbing aerosol optical thickness
  simulated by GOCART model with AERONET and OMI
  data

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• Major absorbers in the solar spectrum are clearly
  dust and BC, both have large seasonal and
  interannual variabilities. OC is weakly
  absorbing in the UV.
• BC becomes more absorbing with wavelength
  increase, dust becomes less absorbing with
  wavelength increase.
• Even though the MEE of BC is much higher than
  that of dust, the mass loading of BC is much
  lower than that of dust.

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Wavelength-dependent SSA
AERONET
Dubovik et al. JAS 2002
GOCART
This work
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Comparisons with AERONET measurements
131 sites have simultaneous AOD and almucantar
retrievals for 20 days or more in 2004 7
regions R1 North America R2 Europe R3
Asia R4 N. Africa/Mid. East R5 South
America R6 Southern Africa R7 Australia
We choose 12 sites to compare seasonal cycles of
daily AOD, absorbing AOD, SSA, and Angstrom
exponents (2 in North America, 2 in Europe, 2 in
Asia, 3 in N. Africa/Middle East, and 1 each in
South America, southern Africa, and Australia)
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Overall comparison of monthly AOD in 2004 at 131
AERONET sites
7 regions R1 North America, R2 Europe, R3
Asia, R4 N. Africa/Middle East, R5 South
America, R6 Southern Africa, R7 Australia
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Comparison of AAOT with OMI (2004)
OMI L3 data 1x1 from Giovanni
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Comparison of AAOT with OMI (2006)
OMI L3 data 1x1 from Giovanni
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Comparison of AAOT with OMI (2006)
OMI L3 data 1x1 from Giovanni
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Conclusions

• Absorption is very important, but it is still
  difficult to constrain model with data
• Much work ahead