摘要
冷季暴雨特别是南方冷季暴雨不但常有发生,其强度和灾害甚至不亚于暖季暴雨。统计表明约有80%的华南冷季强降水与热带卷云羽(简称TP)活动相对应。为此,本文利用近7年FY-2静止气象卫星、TRMM卫星合成降水率数据、ECMWFInterim再分析资料以及地面与探空的常规观测资料等,综合分析了与华南冷季暴雨相关的热带卷云羽的相关特征。分析结果表明,与华南冷季降水有关的TP云产生的源地主要集中在0°~10°N、70°~140°E之间区域内。青藏高原大地形作用对TP引起的华南冷季降水分布具有不可忽视的作用。Hovm6ller图分析显示,TP云在爆发前,云系大多呈连续西传的特征,传播速度约为15~20 m·s^(-1),与大尺度斜压波波速相当或略快。一般来说,与弱降水相比,引起强降水的TP云在爆发前移速较快,受来自对流层中上层的动力强迫影响较大。TP云爆发后,云内强对流区总体移动速度不快,大部分集中在TP云的西南端较小范围内。副热带高空急流只是使得TP云的云盖快速向东扩展。上述特征可能是造成华南冷季强降水中只有个别站点强度大而整体降水强度不强的可能原因。
Cold season rainstorm is not rare in China and sometimes its strength and induced disaster is greater than that of warm season.Statistics show that about 80% cold-season rainstorm events in South China are related to tropical plumes (TP).Therefore,in this paper,seven-year (2005-2011)FY-2 geo-stationary satellite data,TRMM-adjusted merged-infrared precipitation dataset (3B42),ECMWF Interim reanalysis data and conventional observations including surface and soundings are used to examine the char-acteristics and behavior of tropical plumes which are dealt with cold-season rainstorms in South China.The analyses reveal that most of the tropical plumes related to the cold-season rainstorms in South China are generated within 0°-10°N,70°-140°E area.The topographical effect to TP caused by the Tibetan Plateau can not be ignored.According to the propagation characteristics,the tropical plumes before eruption ex- <br> hibit westward propagating in longitude-time (Hovmoller)space,with a preferred phase speed of 15-20 m·s-1 ,comparable to or faster than the synoptic baroclinic wave.Generally,tropical plumes which are related to heavy rainfall always move faster in the pre-eruption stage and are significantly influenced by the dynamic forcing coming from the mid-upper level of troposphere than those dealt with weak rainfall.The pattern of the tropical plumes after eruption in the longitude-time space suggest that the convection part in the cloud moves slowly and concentrates at the south-west end of plumes.The sub-tropical upper level jets act only to make the cloud cover to expand eastward quickly.The above features may cause the heavy rain-fall centralized only over some stations .
出处
《气象》
CSCD
北大核心
2014年第6期687-696,共10页
Meteorological Monthly
基金
国家自然科学基金青年基金项目(41005027)
面上基金项目(41175023)
气象灾害省部共建教育部重点实验室开放课题(KLME0905)
国家高技术研究发展计划(863)(2012AA120903)共同资助
