Source evaluation of the seasonal variation in aerosol optical depth distribution over the Indian subcontinent from combined measurement and modeling platforms

作者:S. Verma;M. Schulz;Y. Balkanski;S. N. Bhanja;S. K. Pani 刊名: 上传者:王振湦

【摘要】Anthropogenic aerosols perturb the radiation energy balance of the earth-atmosphere system and hence impact the earth climate. In contrast to the well-mixed greenhouse gases, which are uniformly mixed around the globe, aerosols exhibit variation in their spatial and temporal characteristics. This could lead to a climate response due to aerosols different on a regional scale than the global. Modeling studies suggest significant link between aerosols and regional climatic effects with a potential to impact large scale circulation and hydrological cycle. Emission fluxes aggregated spatially over India show variation in the regional emission composition, e.g. emission fluxes from the Indo-Gangetic plain (IGP), are mainly composed of sulfate, organic matter, inorganic matter followed by black carbon, while that from northwest India are mainly composed of dust followed by sulfate. On the other hand, the prevalence of different seasonal cycles over Indian subcontinent could further lead to the variation in the chemical and optical characteristic of aerosols. It is therefore, necessary to carryout the source evaluation of chemical and optical characteristics of aerosol during different seasons prevalent over India through integration of measurements and modeling studies. In the present work, we carry out an analysis of aerosol distribution over the Indian subcontinent from aerosol transport simulations in LMDZ-INCA [Schulz et al., 2006] which couples the Laboratoire de Meteorologie Dynamique general circulation model (LMDz) and the Interaction with Chemistry and Aerosols (INCA) model. Simulations of emissions tagged by region are used to understand the relative influence of emissions on aerosol optical depth (AOD). Model estimates showed the AOD over the IGP to be dominated by dust and sulfate during the southwest monsoon compared to sulphate, organic matter, and BC, during the winter monsoon. Evaluation of GCM simulated aerosol optical depth over the Indian subcontinent with the ground-based measurements during the various campaigns and satellite-based observations will be presented. The chemical constituents to the AOD measured and their probable sources will be evaluated.

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