Geoscience Reference
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Fig. 7. The fractional contributions of each type of aerosol to the time-area averaged
column integrated (a) total aerosol mass, (b) anthropogenic aerosol mass, direct radiative
forcing (c) at the surface and (d) at the top of atmosphere averaged in the whole analysis
domain in Fig. 1 for the period from 19 to 22 March, 2002.
the mixed aerosol and IOC, respectively (Fig. 7(c)), implying that the
anthropogenic aerosol has a larger effect on the radiative forcing at the sur-
face due to its small size distribution compared with that of the Asian dust
aerosol.
The mean aerosol radiative forcing at TOA is about -6 W/m
2
,ofwhich
55% is due to the Asian dust aerosol and 45% to the anthropogenic aerosol
(Fig. 7(d)), also implying a larger effect of the anthropogenic aerosol on
the radiative forcing at TOA than the Asian dust aerosol. The difference
between radiative forcing at TOA and at the surface yields an estimate of
the aerosol absorption in the atmosphere. The estimated radiative forcing
due to atmospheric aerosol absorption in East Asia is about 5 W/m
2
.This
implies that aerosols heat the atmosphere significantly over East Asia dur-
ing the dust storm period. The atmospheric heating due to the Asian dust
