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GCM simulations of anthropogenic aerosol-induced changes in aerosol extinction, atmospheric heating and precipitation over India

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Title GCM simulations of anthropogenic aerosol-induced changes in aerosol extinction, atmospheric heating and precipitation over India
 
Creator CHERIAN, R
VENKATARAMAN, C
QUAAS, J
RAMACHANDRAN, S
 
Subject Indian summer monsoon
ECHAM5
5-HAM model
anthropogenic aerosols
aerosol-induced rainfall changes
aerosol radiative forcing
convective precipitation
ASIAN SUMMER MONSOON
GLOBAL CLIMATE MODEL
BLACK CARBON AEROSOLS
LARGE-SCALE MODELS
SATELLITE DATA
HYDROLOGICAL CYCLE
NORTHERN INDIA
GANGETIC BASIN
IPCC AR4
CLOUDS
 
Description The influence of anthropogenic emissions on aerosol distributions and the hydrological cycle are examined with a focus on monsoon precipitation over the Indian subcontinent, during January 2001 to December 2005, using the European Centre for Medium-Range Weather Forecasts-Hamburg (ECHAM5.5) general circulation model extended by the Hamburg Aerosol Module (HAM). The seasonal variability of aerosol optical depth (AOD) retrieved from the MODerate Resolution Imaging Spectroradiometer (MODIS) on board the Terra and Aqua satellite is broadly well simulated (R approximate to 0.6-0.85) by the model. The spatial distribution and seasonal cycle of the precipitation observed over the Indian region are reasonably well simulated (R approximate to 0.5 to 0.8) by the model, while in terms of absolute magnitude, the model underestimates precipitation, in particular in the south-west (SW) monsoon season. The model simulates significant anthropogenic aerosol-induced changes in clear-sky net surface solar radiation (dimming greater than -7 W m-2), which agrees well with the observed trends over the Indian region. A statistically significant decreasing precipitation trend is simulated only for the SW monsoon season over the central-north Indian region, which is consistent with the observed seasonal trend over the Indian region. In the model, this decrease results from a reduction in convective precipitation, where there is an increase in stratiform cloud droplet number concentration (CDNC) and solar dimming that resulted from increased stability and reduced evaporation. Similarities in spatial patterns suggest that surface cooling, mainly by the aerosol indirect effect, is responsible for this reduction in convective activity. When changes in large-scale dynamics are allowed by slightly disturbing the initial state of the atmosphere, aerosol absorption in addition leads to a further stabilization of the lower troposphere, further reducing convective precipitation.
 
Publisher AMER GEOPHYSICAL UNION
 
Date 2014-10-16T15:23:10Z
2014-10-16T15:23:10Z
2013
 
Type Article
 
Identifier JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 118(7)2938-2955
2169-897X
2169-8996
http://dx.doi.org/10.1002/jgrd.50298
http://dspace.library.iitb.ac.in/jspui/handle/100/15893
 
Language en