A New Pathway for Absorbing Aerosols’ Influence on the Interannual Variability of the South Asian Monsoon

Aerosol forcing remains the dominant uncertainty and a challenging problem in climate change scenarios. While it is widely documented that anthropogenic activities have significantly contributed to raising the global aerosol concentration in the troposphere, quantification of the influence of tropospheric aerosols on climate has proved difficult because of the large spatial and temporal variability of aerosols, their short lifetimes, their diverse physical and chemical properties, and complex interactions that take place with radiation and microphysical processes. Aerosol particles can influence clouds and the water and energy cycles by directly affecting the radiation balance (the “direct” effect) and by impacting the microphysics of clouds and precipitation (the “indirect” effect). A “semi-direct” effect is also known, consisting of the evaporation of the cloud layer from aerosol absorption of solar radiation, with consequent increase in the amount of solar radiation reaching the surface.