Climate implications of large warming by elevated aerosol over India

Abstract

Wide-ranging multi-platform data from a major field campaign conducted over Indian region was used to estimate the energy absorbed in ten layers of the atmosphere. We found that during pre-monsoon season, most of Indian region is characterized by elevated aerosol layers. Three-fold increase in aerosol extinction coefficient was observed at higher atmospheric layers (>2 km) compared to that near the surface and a substantial fraction (as much as 50 to 70%) of aerosol optical depth was found contributed by aerosols above (reflecting) clouds. Consequent absorption and hence strong warming above clouds was found larger by several degrees (K) compared to that near the surface. The aerosol-induced elevated warming was mostly confined below 2 km over northern Indian Ocean while found up to 4 km over central India, thus exhibiting strong meridional gradients (∼4 K) at atmospheric levels above 2 km. Climate implications of the large elevated warming are discussed. Copyright 2008 by the American Geophysical Union.