孟加拉湾风暴对高原地区降水的影响

Impact of Bay of Bengal Storms on Precipitation over Plateau Area

利用卫星遥感数据TRMM(3B42)与地面观测数据变分订正后的降水量资料、TBB资料、NCEP/NCAR再分析资料,对1998 2010年25个孟加拉湾风暴的登陆路径、强度、冷空气入侵及大气季节变化对高原地区降水的影响进行了分类统计分析,结果表明:(1)孟加拉湾风暴是造成高原地区降水的重要天气系统,最活跃的时段集中在5月和10 11月,对高原地区的影响主要以降水为主;(2)在孟加拉湾风暴登陆的3条路径中,东北路径对云贵高原和青藏高原东南部地区影响最大,西北路径登陆风暴主要影响青藏高原南部地区,偏西路径登陆风暴对高原地区影响最小;(3)东北路径登陆风暴,热带风暴强度比飓风强度给高原地区带来更强的降水,而西北路径飓风强度风暴的影响较大;(4)当东北路径孟加拉湾风暴与云贵高原地区冷空气相遇时,其降水量比无冷空气配合时大2个等级;(5)孟加拉湾风暴活动时段存在5月和10 11月两个峰值,因季节性的大气环流(引导气流)和水汽输送(强弱)以及热带气旋生成基本条件的不同,导致了高原地区降水程度的差异。

By using TBB data,NCEP / NCAR reanalysis data and precipitation assimilation data from TRM M( 3B42) and rain gauge data,the influence of landing path,impact strength,cold air intrusion and atmospheric seasonal changes of 25 processes of Bay of Bengal storms from 1998 to 2010 on precipitation over the plateau region w ere classified statistical analyzed. The results show that:( 1) The Bay of Bengal Storm is the important weather system affected rainfall over the plateau area. Its most active period focused on the annual M ay and October to November.( 2) The landing path of Bay of Bengal storm can be divided into three categories,NE( northeast),NW( northwest) and W( west) paths. Storms from NE path landing with maximal impact rainfall over Yunnan-Guizhou Plateau and the southeast of the Qinghai-Xizang Plateau. Storms from NW path landing mainly affected the south of the Qinghai-Xizang Plateau. Storms from W path landing with minimal impact on the Qinghai-Xizang Plateau.( 3) Storm from NE path landing with TS( tropical storm) intensity can bring more precipitation for plateau than the H( hurricane) intensity,and to NW path,the H intensity can bring more precipitation for plateau that the TS.( 4) For storms from NE path landing,w hen mated with cold air over YunnanGuizhou Plateau,the precipitation can reach more than 15 mm,even 50 mm or more in some areas. But,w hen no cold air,the precipitation does not exceed 15 mm.( 5) Seasonal atmospheric circulation( steering flow) and w ater vapor transport( strength) and tropical cyclone formation conditions are different betw een tw o storms activities peak periods in M ay and October to November. The differences lead to different scale precipitation on the plateau.