Atmos. Chem. Phys. Discuss., 11, 7291-7319, 2011
www.atmos-chem-phys-discuss.net/11/7291/2011/
doi:10.5194/acpd-11-7291-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Satellite-based evidence of wavelength-dependent aerosol absorption in biomass burning smoke inferred from ozone monitoring instrument
H. Jethva1 and O. Torres2
1Department of Atmospheric & Planetary Sciences, Hampton University, Hampton, VA 23668, USA
2NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA

Abstract. We provide satellite-based evidence of the spectral dependence of absorption in biomass burning aerosols over South America using near-UV measurements made by Ozone Monitoring Instrument (OMI) during 2005–2007. Currently, OMAERUV aerosol algorithm characterizes carbonaceous aerosol as "gray" aerosol, meaning no wavelength dependence in aerosol absorption. With this assumption, OMI-derived aerosol optical depth (AOD) is found to be over-estimated significantly compared to that of AERONET at several sites during intense biomass burning events (August–September). The assumption on height of aerosols and other parameters seem to be reasonable and unable to explain large discrepancy in the retrieval. The specific ground-based studies have revealed strong spectral dependence in aerosol absorption in the near-UV region that indicates the presence of organic carbon. A new set of OMI aerosol retrieval with assumed wavelength-dependent aerosol absorption in the near-UV region (Absorption Angstrom Exponent λ−2.5 to −3.0) provided much improved retrieval of AOD with significantly reduced bias. Also, the new retrieval of single-scattering albedo is in better agreement with those of AERONET within the uncertainties (Δω=±0.03). The new smoke aerosol model was also found to be valid over the biomass burning region of central Africa and northern India. Together with suggesting vast improvement in the retrieval of aerosol properties from OMI, present study demonstrates the near-UV capabilities of OMI in separating aerosols containing organics from pure black carbon through OMI-AERONET integrated measurements.

Citation: Jethva, H. and Torres, O.: Satellite-based evidence of wavelength-dependent aerosol absorption in biomass burning smoke inferred from ozone monitoring instrument, Atmos. Chem. Phys. Discuss., 11, 7291-7319, doi:10.5194/acpd-11-7291-2011, 2011.
 
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