Overview of aerosol–cloud interactions over Indian summer monsoon region using remote sensing observations

Aerosols are suspended solid or liquid particles in the atmosphere produced from natural and anthropogenic sources. Atmospheric aerosols can exert a cooling and warming on earth’s climate by directly scattering and absorbing, respectively, solar, and terrestrial radiation. They can also affect cloud formation processes indirectly by acting as cloud condensation nuclei (CCN), and thereby modifying cloud radiative forcing and precipitation patterns, referred to as aerosol indirect effect (AIE). Despite extensive studies over the last more than three decades, aerosols impact on clouds and precipitation patterns constitutes the largest uncertainty. This ambiguity in AIE is primarily due to the regional variability in aerosols, clouds, and the complexity of aerosol-associated changes in macro- and micro-physical and/or dynamical feedbacks at different spatio-temporal scales. Moreover, the influence of environmental conditions and contingent surface feedbacks on aerosol–cloud interactions is also a considerable source of uncertainty in estimates of AIE. General circulation models (GCMs) are used for predicting future climate, but the treatment of aerosols, clouds, and particularly aerosol–cloud interactions carry large uncertainties that directly affect GCM predictions. In this chapter, the review of aerosol–cloud interactions over the Indian summer monsoon region viewed by space-borne and ground-based remote sensing techniques is presented.