DOI: 10.1007/s00382-012-1638-z
Scopus记录号: 2-s2.0-84879499929
论文题名: Impacts of enhanced CCN on the organization of convection and recent reduced counts of monsoon depressions
作者: Krishnamurti T.N. ; Martin A. ; Krishnamurti R. ; Simon A. ; Thomas A. ; Kumar V.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2013
卷: 41, 期: 1 起始页码: 117
结束页码: 134
语种: 英语
英文关键词: Cloud condensation nuclei (CCN)
; Indian monsoon
; Monsoon depression
英文摘要: Monsoon depressions, that form during the Indian summer monsoon season (June to September) are known to be baroclinic disturbances (horizontal scale 2,000-3,000 km) and are driven by deep convection that carries a very large vertical slope towards cold air aloft in the upper troposphere. Deep convection is nearly always organized around the scale of these depressions. In the maintenance of the monsoon depression the generation of eddy kinetic energy on the scale of the monsoon depression is largely governed by the "in scale" covariance of heating and temperature and of vertical velocity and temperature over the region of the monsoon depression. There are normally about 6-8 monsoon depressions during a summer monsoon season. Recent years 2009, 2010 and 2011 saw very few (around 1, 0 and 1 per season respectively). The best numerical models such as those from ECMWF and US (GFS) carried many false alarms in their 3-5 day forecasts, more like 6-8 disturbances. Even in recent years with fewer observed monsoon depressions a much larger number of depressions is noted in ECMWF forecasts. These are fairly comprehensive models that carry vast data sets (surface and satellite based), detailed data assimilation, and are run at very high resolutions. The monsoon depression is well resolved by these respective horizontal resolutions in these models (at 15 and 35 km). These models carry complete and detailed physical parameterizations. The false alarms in their forecasts leads us to suggest that some additional important ingredient may be missing in these current best state of the art models. This paper addresses the effects of pollution for the enhancement of cloud condensation nuclei and the resulting disruption of the organization of convection in monsoon depressions. Our specific studies make use of a high resolution mesoscale model (WRF/CHEM) to explore the impacts of the first and second aerosol indirect effects proposed by Twomey and Albrecht. We have conducted preliminary studies including examination of the evolution of radar reflectivity (computed inversely from the model hydrometeors) for normal and enhanced CCN effects (arising from enhanced monsoon pollution). The time lapse histories show a major disruption in the organization of convection of the monsoon depressions on the time scale of a week to 10 days in these enhanced CCN scenarios. © 2012 Springer-Verlag Berlin Heidelberg. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/54878
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, 32306, United States
Recommended Citation:
Krishnamurti T.N.,Martin A.,Krishnamurti R.,et al. Impacts of enhanced CCN on the organization of convection and recent reduced counts of monsoon depressions[J]. Climate Dynamics,2013-01-01,41(1)