2010年长江暴雨洪水成因及与1998年洪水比较

Genesis of 2010 storm-flood in Yangtze River Basin and its comparison with 1998 flood

2010年主汛期,长江流域洞庭湖与鄱阳湖两湖水系、长江中下游干流附近、长江上游嘉岷流域和汉江上中游先后出现强降雨过程,长江流域大多地区相继发生洪涝灾害,造成长江上中游区域性较大洪水。通过分析比较2010年长江上中游区域性洪水与1998年流域性大洪水,发现2次洪水在气候背景和大尺度环流形势上有共同之处:①都是赤道中东太平洋海温发生厄尔尼诺事件的次年,只是强度上有明显差异;②夏季风偏弱;③台风偏少;④西太平洋副热带高压显著偏强、异常偏西。但也有明显差异:1997/1998年秋冬季青藏高原积雪异常偏多,而2009/2010年秋冬季青藏高原积雪偏少;1998年汛期亚欧中高纬度地区稳定存在东西两个阻塞高压,2010年汛期上述地区未出现明显阻塞形势。

In the main flood season,the strong rainfall process successively occurred in the Dongting Lake and Poyang Lake systems,the areas along the mainstream of the middle and lower Yangtze River,the Jialing River Basin and Minjiang River Basin in the upper Yangtze River and upper and middle Hanjiang River,which formed the basin-wide flood disaster.Through analysis and comparison of flood in 2010 and 1998,it is discovered that there are 4 common points of the 2 floods in climatic background and macro-scale atmospheric circulation： both the 2 floods occurred after El Nino phenomenon emerged in middle-east Pacific in previous year;summer monsoon was weak;typhoon was less;subtropical high over the Western Pacific was obviously strong and abnormally westward.However,there were some obvious differences in the 2 floods ： the snow cover on Qinghai-Tibet Plateau from 1997 to 1998 was abnormally more,while the snow cover on Qinghai-Tibet Plateau from 2009 to 2010 was less;2 flood season blocking highs existed in Eurasian mid-high latitude region in the flood season of 1998,while there was no obvious blocking high in the same region in the flood season of 1998.