The radiative effect of aerosols from biomass burning on the transition from dry to wet season over the amazon as tested by a regional climate model

Aerosol;Amazon;Regioncal climate model;Radiative forcing

Zhang, Yan ; Earth and Atmospheric Sciences

University:Georgia Institute of Technology

Department:Earth and Atmospheric Sciences

关键词: Aerosol;    Amazon;    Regioncal climate model;    Radiative forcing;   

Others  :  https://smartech.gatech.edu/bitstream/1853/26510/1/Zhang_Yan_200812_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

Ensemble simulations of smoke aerosol radiative effects with a regional climate model in the Amazon has been conducted to investigate the radiative effects of aerosols on clouds, rainfall, and circulation from dry to wet season.The results of the ensemble simulations suggest that the radiative effect of the smoke aerosols can reduce daytime surface radiative and sensible fluxes, the depth and instability of the planetary boundary layer (PBL), consequently the clouds in the lower troposphere in early afternoon in the smoke center, where the aerosols optical depth, AOD, exceeds 0.3.The aerosol radiative forcing also appears to weaken moisture transport into the smoke center and increase moisture transport and cloudiness in the region upwind to the smoke center, namely, the northern Amazon. Anomalous wind convergence over the equatorial western Amazon occurs to compensate the anomalous wind divergence in the southern Amazon, leading to an increase of both clouds and rainfall in that region.The increased atmospheric thermodynamic stability in Southern Amazonia also appears to block synoptic cyclonic activities propagated from extratropical South America, leading to an increased synoptic cyclonic activities and rainfall in southern Brazil, Paraguay and northern Argentina.Evidently, the dynamic response of the monsoon circulation plays a major role in determining the pattern of rainfall change induced by the radiative effect of the aerosols.