The Indian summer monsoon rainfall: interplay of coupled dynamics, radiation and cloud microphysics

[摘要] The Indian summer monsoon rainfall (ISMR), which has a strongconnection to agricultural food production, has been less predictable byconventional models in recent times.Two distinct years 2002 and 2003with lower and higher July rainfall, respectively, are selected to helpunderstand the natural and anthropogenic influences on ISMR. We show thatheating gradients along the meridional monsoon circulation are reduceddue to aerosol radiative forcing and the Indian Ocean Dipole in 2002. Anincrease in the dust and biomass-burning component of the aerosols throughthe zonal monsoon circulation resulted in reduction of cloud droplet growthin July 2002.These conditions were opposite to those in July 2003 which ledto an above average ISMR.In this study, we have utilized NCEP/NCARreanalyses for meteorological data (e.g. sea-surface temperature,horizontal winds, and precipitable water), NOAA interpolatedoutgoing long-wave radiation, IITM constructed all-India rainfallamounts, aerosol parameters as observed from the TOMSand MODIS satellites, and ATSR fire count maps.Based on this analysis, wesuggest that monsoon rainfall prediction models should includesynoptic as well as interannual variability in both atmosphericdynamics and chemical composition.

[学科分类] 大气科学