江淮流域持续性暴雨过程的中期信号初析  

Preliminary study on medium-range signals of persistent heavy rainfall events over Yangtze River-Huaihe River Valley

作　　者：甘晶晶[1] 汤燕冰[1] 

机构地区：[1]浙江大学地球科学系,浙江杭州310027

出　　处：《浙江大学学报（理学版）》2009年第4期477-486,共10页Journal of Zhejiang University（Science Edition）

基　　金：国家自然科学基金资助项目(40575015)

摘　　要：江淮流域持续性暴雨过程是造成大范围洪涝的高影响天气事件,了解导致此类事件的全球和区域影响,对改进其预报是十分必要的.针对1951～2004年间16个典型个例,利用NCEP再分析资料,对事件发生前1～30d的全球环流场进行了相关与合成分析相结合的天气学统计普查,揭示了与此类过程显著相关的前期环流信号的时空分布特征,并初步探讨了主要信号对过程形成可能的影响和联系:过程前3～4k,赤道太平洋对流层中高层的暖性高压增强,并通过遥相关影响后期西太平洋副热带高压加强西伸及白令海附近低压的形成和加深;同期,南美洲南部南极附近的冷槽加深,其后能量频散至马达加斯加岛附近,有利于前2～3k南印度洋副热带地区以及西南太平洋西风带地区显著Rossby波列的出现,相应在马达加斯加岛南侧、澳大利亚西侧及新西兰东侧洋面上分别出现显著的低槽加深,经向环流增强;马达加斯加岛附近的纬向风异常通过经向遥相关对应北半球欧洲地区所出现的多个正负相间的纬向风异常,导致欧洲中纬度环流经向度加大,从而触发欧亚Rossby波列的形成和东传,该波列中三个稳定的波槽分别位于伊朗高原、我国东部洋面和太平洋中部洋面,并使青藏高压加强北挺;最后随着波列消失,我国东部洋面低槽减弱北缩,副热带高压趋于加强西伸,促使事件的背景环流条件最终形成.Persistent heavy rainfall （PHR） events over the Yangtze and Huaihe River Valley are one of the weather related high impact events. To improve the forecast skill for the PHR events, it is necessary to find out the global to regional influences on the initiation and evolution of this kind of event. By using fifty year NCEP/NCAR reanalysis datasets, the lag correlation and composite analysis are conducted to identify the medium-range signals leading to the onset of the events. The signals are defined as the significant anomalies of atmospheric circulation fields and correlated closely with the consequent events. The revealed significant signals include a） strengthening of the warm subtropical high over the equatorial Pacific in three to four weeks preceding the events, which affects subtropical high and the height anomalies near Bering sea through teleconnection; b） almost at the same time, energy of the stronger cold trough on the south of South America near South Pole disperses to Madagascar, which is favor of the occurrence of two Rossby wave trains over the subtropical area of the southern Indian Ocean and in the westerlies of the southwest Pacific respectively, which are accompanied by three major troughs locating respectively to the south of Madagascar, west of Australia and east of New Zealand in two to three weeks before to the events; c） by meridional teleconnection of zonal wind, the increased meridional circulation on Europe causes the development of a prominent Rossby wave train in the westerlies of the Eurasian continent, which are associated with three stable troughs separately over the Iran Plateau, off the coast of East China and the central north Pacific in one to two weeks before the events. All these signals, especially the last one, are in favor of the formation of the large scale circulation background governing the events.

关 键 词：持续性暴雨过程 相关分析 中期信号 江淮流域 

分 类 号：P458[天文地球—大气科学及气象学] P168