Radiative forcing by aerosols over Bay of Bengal region

Abstract

Estimates of aerosol radiative (short wave and long wave) forcing over Bay of Bengal region are made from observations conducted as part of validation experiment of Indian Remote Sensing satellite, IRS-P4. Aerosol visible optical depths were as high as 0.6 and aerosol single scattering albedo were as low as 0.85 indicating the presence of significant amount of absorbing aerosols. The presence of aerosol over Bay of Bengal decreases the short wave radiation arriving at the surface by as much as 38 W m⁻² and increases the top of the atmosphere reflected radiation by 7 W m⁻². In the long wave region, the corresponding forcing values are +11 W m⁻² (increase) at the surface and +3 W m⁻² (decrease). The short wave atmospheric absorption translates to an atmospheric heating of 0.5° to 1°K/day which is an increase of ∼60–80% of the aerosol-free solar heating.