Absorbing aerosols and summer monsoon evolution over South Asia: An observational portrayal
Absorbing aerosols and summer monsoon evolution over South Asia: An observational portrayal
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DOI：
10.1175/2007jcli2094.1
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发表时间：
2008-07-01
影响因子：
4.9
通讯作者：
Lau, K. -M.
中科院分区：
文献类型：
--
作者：
Bollasina, Massimo;Nigam, Sumant;Lau, K. -M.
南亚的霾从12月到5月逐渐形成，主要是人为造成的，并吸收了部分太阳辐射。通过观测分析，研究了5月印度-恒河平原上空吸收气溶胶的年际变化对印度夏季风的影响。研究结果还表明，晚春气溶胶的异常负荷导致了季风演变中显著的大尺度变化。5月气溶胶过多导致云量和降水减少，地表短波辐射增加，陆面变暖。6月（和7月）季风异常与过量的5月气溶胶是相反的迹象超过了大部分的次大陆（虽然有不同的模式）相对于5月。分析表明，大尺度气溶胶对季风环流和水文气候的显著影响是通过加热陆面来实现的，而5月云量和降水量的减少则是通过加热陆面来实现的。陆地表面在实现气溶胶影响方面的重要作用的发现有些新颖。
The South Asian haze builds up from December to May, is mostly of anthropogenic origin, and absorbs part of the solar radiation. The influence of interannual variations of absorbing aerosols over the Indo-Gangetic Plain in May on the Indian summer monsoon is characterized by means of an observational analysis. Insight into how the aerosol impact is generated is also provided.It is shown that anomalous aerosol loading in late spring leads to remarkable and large-scale variations in the monsoon evolution. Excessive aerosols in May lead to reduced cloud amount and precipitation, increased surface shortwave radiation, and land surface warming. The June ( and July) monsoon anomaly associated with excessive May aerosols is of opposite sign over much of the subcontinent (although with a different pattern) with respect to May. The monsoon strengthens in June ( and July).The analysis suggests that the significant large-scale aerosol influence on monsoon circulation and hydroclimate is mediated by the heating of the land surface, pursuant to reduced cloudiness and precipitation in May. The finding of the significant role of the land surface in the realization of the aerosol impact is somewhat novel.