西江流域面雨量与区域大气环流型关系  

Relationship Between Areal Rainfall and Circulation Characteristics in Xijiang River Basins

作　　者：钟利华 曾鹏 史彩霞 古文保[2] 李勇 

机构地区：[1]广西壮族自治区气象服务中心,南宁530022 [2]广西壮族自治区气象减灾研究所,南宁530022

出　　处：《应用气象学报》2017年第4期470-480,共11页Journal of Applied Meteorological Science

基　　金：广西科学研究与技术开发计划项目(1598017-15);国家自然科学基金项目(41575051);广西自然科学基金项目(2016GXNSFAA380330)

摘　　要：利用Lamb-Jenkinson大气环流分型方法,对西江流域1971—2015年逐日平均850 hPa和500 hPa高度场进行环流客观分型,分析流域降水天气环流型出现概率及主导环流型变化特征,探讨主导环流型对西江流域总面雨量和子流域面雨量的贡献率及环流型配置与降水的关系。结果表明:当850 hPa为西南风型、500 hPa为西风型时,流域出现降水天气的概率最大;850 hPa气旋型和500 hPa西风型对年总面雨量和各子流域面雨量的贡献率均为最大,且对东部子流域面雨量的贡献率大于西部子流域,850 hPa南风型与500 hPa反气旋型的环流配置是西部子流域秋季降水偏多的主导环流型配置;春季850 hPa气旋型与500 hPa西风型、夏季850 hPa气旋型与500 hPa西风型、秋季850 hPa南风型与500 hPa反气旋型、冬季850 hPa西南风型与500 hPa西风型的环流配置时,出现强降水天气的概率分别为18.7%,21.1%,4.0%和2.0%,即夏季最大,其次为春季,冬季最小。近45年,850 hPa气旋型、500 hPa西风型对流域年总面雨量的贡献率呈增加趋势,是西江流域面雨量呈偏多趋势的主导环流型。The reanalysis grid data of daily average 850 hPa and 500 hPa geopotential height field during 1971-2015 provided by NCEP/NCAR are used for computing six daily circulation indices of Xijiang River Basins using Lamb-Jenkinson atmospheric circulation classification method. The daily circulation is divided into straight wind type, rotary type and mixed type according to the relationship between the geostrophic wind speed, wind direction and the geostrophic vorticity. The circulation frequency of precipitation weather cir culation in Xijiang River Basins is researched, showing that the probability of precipitation is the greatest when the circulation is southwest wind type at 850 hPa and west wind type at 500 hPa, which is the domi- nant circulation for precipitation in Xijiang River Basins. The contribution rate of different types of circulation to the total areal rainfall is calculated, and types with top 3 contribution rates are called the dominant circulation pattern. It＇s found that for the annual to- tal rainfall and sub basin rainfall, the cyclone type at 850 hPa and westerly type at 500 hPa has the maxi mum contribution in each layer. The contribution of areal rainfall is larger in the east part and smaller in the west part of Xijiang River Basins. The main configuration of south wind type at 850 hPa and anticy clone type at 500 hPa causes rainy autumn over the western sub basin. By the influence situation of the first dominant circulation configuration of season total areal rainfall contribution for strong precipitation, it shows that the probability of strong precipitation are 21. 1%, 18.7% and 2.0% while the configuration are cyclone at 850 hPa and west wind type at 500 hPa in summer or spring,south wind at 850 hPa and anticyclone type at 500 hPa in autumn,southwest wind at 850 hPa and west wind type at 500 hPa in winter, respectively, Analysis on the dominant circulation configuration for season rainfall indicate that, in spring and sum mer it＇s cyclone at 850 hPa and westerly at 500 hPa, in autumn

关 键 词：Lamb-Jenkinson 环流分型 西江流域 面雨量 贡献率 

分 类 号：P426.6[天文地球—大气科学及气象学] P434