Radiative forcing of Asian dust determined from the synergized GOME and GMS satellite data - A case study

A method developed for aerosol characterisation and estimating aerosol optical thickness over the sea surface and direct shortwave aerosol radiative forcing (Costa et al., 2002, 2004a) was applied to a Yellow Sand event which occurred on 7 April 2000. Data from the GEO Meteorological Satellite (GMS-5) was used in conjunction with GOME measurements. In results, both satellite analysis and surface solar radiation measurements indicate that the single scattering albedo was as low as 0.76, much smaller than the values of 0.9 (Kim et al., 2005) found in an Asian dust source region such as Dunhuang or 0.93 for Saharan dust (Tanre et al., 2001). This finding suggests that Asian dust can become a much more absorbing aerosol during movement when mixed with pollution materials produced over the industrial/urban area of China. The overall atmospheric forcing efficiency (radiation flux per unit aerosol optical thickness at 0.5 micron) of Asian dust observed on 7 April 2000 is about 102 Wm-2 while it was –116.9 Wm-2 at the surface. These findings strongly indicate that substantial atmospheric heating and surface cooling can result from the presence of Asian dust.