Retrival of Atmosph Eric Aerosol Optical and Microphysical Parameters from Ground Base Passive Remote Sensing Measurement over Addis Ababa
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Date
2009-03
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Addis Ababa University
Abstract
Aerosol optical depth is determined from measurements of atmospheric effective spectral
transmission, for clear-sky days on May 21, 2008 and May 23, 2008, at Addis Ababa
(9° 1′ 48″ N, 38° 44′ 24″ E) carried out using pyrheliometer, which we constructed in
department of physics at AAU. It has effective discrete optical channels in the range
between 0.699mm and 0.753mm. With in framework of Mie theory and non-linear
inversion method, column integrated effective optical and microphysical parameters are
retrieved. The effective refractive index, temporal variation related to atmospheric
particle size distribution, and modeling the effect of water vapor implies that,
atmospheric aerosols have chemically distinct compositions due to their different sources
and the hygroscopic growth is facilitated by chemical alterations. Removal processes of
particles are more efficient when the aerosol size increases. Retrieved real part of
effective refractive index ranges between 1.53 and 1.59 while computed single scattering
albedo ( 0
w ) ranges between 0.98 and 0.99. This is indicating that dust is by far the
dominant aerosol component in Addis Ababa
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Keywords
Remote Sensing Measurement over Addis Ababa