P1.9
Radiative Forcing of Dust Haze over the Northern Indian Ocean during Winter and Summer Monsoons
I.A. Podgorny, SIO/Univ. of California, La Jolla, CA; and V. Ramanathan and C. E. Chung
Satellite aerosol and cloud data from Moderate Resolution Imaging Spectroradiometer (MODIS) and International Satellite Cloud Climatology Project (ISCCP) and direct aerosol observations have been integrated with a Monte Carlo radiative transfer model to quantify the annual cycle of the all-sky dust radiative forcing over the Northern Indian Ocean. The dust radiative forcing in both short-wave and long-wave regions exhibits a distinctive annual cycle reaching the maximum during summer monsoon over the Arabian Sea. The effect of clouds on the forcing is the strongest during summer monsoon as the Inter-Tropical Convective Zone moves closer to the Indian subcontinent. The atmospheric forcing (aerosol absorption) during summer monsoon is most sensitive to the uncertainties in mineral dust single-scattering albedo (SSA) and aerosol vertical profile over the Arabian Sea. The surface forcing is equally sensitive to uncertainties in aerosol optical depth (AOD) and SSA. Also the decrease in the surface solar radiation during summer monsoon is partly offset by the positive mineral dust radiative forcing in the long-wave domain. While the absorbing aerosols over the Northern Indian Ocean have been shown to affect the winter monsoon circulation in a substantial way, further research is needed to understand if the aerosol impacts during summer monsoon can be equally important for the regional climate and hydrological cycle. To further improve the accuracy of aerosol forcing calculations over the Northern Indian Ocean, the future observational efforts in the region should be focused on extensive SSA measurements during the summer monsoon as well as on quantifying the mixing state of the mineral dust and black carbon.
Poster Session 1, Poster Session - Seventh Conference on Atmospheric Chemistry
Monday, 10 January 2005, 1:30 PM-4:00 PM
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