资源环境科技发展态势分析平台

Changes in anthropogenic aerosol loading affect cloud albedo and the Earth's radiative balance with a low level of scientific understanding. Aerosol-cloud interaction and its effects on climate are mainly evaluated using passive observations in a global scale. Here this study estimated the intrinsic response of clouds to aerosols by combining active and passive satellite observations from July 2006 to February 2011 in South Asia. We evaluate the average radiative forcing by the intrinsic aerosol-cloud interaction for warm liquid clouds as 0.63 +/- 0.19, -0.34 +/- 0.40, and 1.11 +/- 0.08 W/m(2) during the annual, monsoon, and nonmonsoon periods in South Asia, respectively. Relationships derived among liquid water path, cloud droplet number concentration, and consequent cloud albedo are assessed as a function of aerosol concentration. The intensity of the aerosol-cloud interaction gradually weakens with increasing cloud base height above ground level in South Asia, is associated with aerosol vertical distribution and vertical atmospheric upward motion. Moreover, distinct regional and seasonal variations in the aerosol-cloud interaction are observed for liquid water path, cloud droplet number concentration, and the resulting cloud albedo in South Asia. These variations are associated with water vapor and aerosol absorption levels. Results contribute to the understanding and modeling of aerosol-cloud interactions and determining their effects on radiative forcing and climate in South Asia.