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A Seasonal Trend of Single Scattering Albedo in Southern African Biomass-burning Particles: Implications for Satellite Products and Estimates of Emissions for the World's Largest Biomass-burning SourceAs a representative site of the southern African biomass-burning region, sun-sky data from the 15 year Aerosol Robotic Network (AERONET) deployment at Mongu, Zambia, was analyzed. For the biomass-burning season months (July-November), we investigate seasonal trends in aerosol single scattering albedo (SSA), aerosol size distributions, and refractive indices from almucantar sky scan retrievals. The monthly mean single scattering albedo at 440 nm in Mongu was found to increase significantly from approx.. 0.84 in July to approx. 0.93 in November (from 0.78 to 0.90 at 675 nm in these same months). There was no significant change in particle size, in either the dominant accumulation or secondary coarse modes during these months, nor any significant trend in the Angstrom exponent (440-870 nm; r(exp 2) = 0.02). A significant downward seasonal trend in imaginary refractive index (r(exp 2) = 0.43) suggests a trend of decreasing black carbon content in the aerosol composition as the burning season progresses. Similarly, burning season SSA retrievals for the Etosha Pan, Namibia AERONET site also show very similar increasing single scattering albedo values and decreasing imaginary refractive index as the season progresses. Furthermore, retrievals of SSA at 388 nm from the Ozone Monitoring Instrument satellite sensor show similar seasonal trends as observed by AERONET and suggest that this seasonal shift is widespread throughout much of southern Africa. A seasonal shift in the satellite retrieval bias of aerosol optical depth from the Moderate Resolution Imaging Spectroradiometer collection 5 dark target algorithm is consistent with this seasonal SSA trend since the algorithm assumes a constant value of SSA. Multi-angle Imaging Spectroradiometer, however, appears less sensitive to the absorption-induced bias.
Document ID
20140016775
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1002/jgrd.50500
Authors
Eck, T. F. (Universities Space Research Association Columbia, MD, United States)
Holben, B. N. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Reid, J. S. (Naval Research Lab. Monterey, CA, United States)
Mukelabai, M. M. (Zambia Univ. Lusaka, Zambia)
Piketh, S. J. (North-West Univ. Potchefstroom, South Africa)
Torres, O. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Jethva, H. T. (Universities Space Research Association Columbia, MD, United States)
Hyer, E. J. (Naval Research Lab. Monterey, CA, United States)
Ward, D. E. (Enviropyronics White Salmon, WA)
Dubovik, O. (Lille-1 Univ. Villeneuve-d'Asoq, France)
Sinyuk, A. (Sigma Space Corp. Lanham, MD, United States)
Schafer, J. S. (Sigma Space Corp. Lanham, MD, United States)
Giles, D. M. (Sigma Space Corp. Lanham, MD, United States)
Sorokin, M. (Sigma Space Corp. Lanham, MD, United States)
Smirnov, A. (Sigma Space Corp. Lanham, MD, United States)
Slutsker, I. (Sigma Space Corp. Lanham, MD, United States)
Date Acquired
November 26, 2014
Publication Date
June 19, 2013
Publication Information
Publication: Journal of Geophysical Research: Atmospheres
Publisher: American Geophysical Union
Volume: 118
Issue: 12
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN14590
Funding Number(s)
CONTRACT_GRANT: NNG11HP16A
CONTRACT_GRANT: NNG09HP18C
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
aerosol absorption
biomass burning
southern Africa

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