西南地区春季降水异常与大尺度环流关系  

Relation between spring precipitation anomaly in southwest China and large-scale circulation

作　　者：范思睿[1,2] 王维佳[1] 陈添宇[3,4] 胡德强[5] 

机构地区：[1]四川省人工影响天气办公室,四川成都610072 [2]高原与盆地暴雨旱涝灾害四川省重点实验室,四川成都610072 [3]中国气象科学研究院,北京100081 [4]中国气象科学研究院中国气象局人工影响天气中心,北京100081 [5]海南省气候中心,海南海口570203

出　　处：《干旱区地理》2016年第1期47-57,共11页Arid Land Geography

基　　金：公益性行业(气象)科研专项(GYHY201406032);国家自然科学基金青年基金项目(41105098)

摘　　要：根据1961-2013年NCEP/NCAR逐月再分析资料、NOAA月平均海表温度资料和西南地区(四川、重庆、贵州、云南)116个气象台站逐月降水资料,利用EOF分析等方法分析了西南地区春季降水空间分布特征,研究了西南地区春季降水异常与大气环流的关系。结果表明:西南地区春季降水不仅有区域一致的增加趋势,还表现出纬向偶极型空间分布;西南地区春季东部降水偏多西部偏少时,受到印度洋和太平洋两个反气旋气流影响,利于印度洋地区的暖湿水汽和西太平暖湿气流的输送,有利于该地区降水偏多;东部降水偏少西部偏多时,东亚大槽、乌拉尔山高压脊、南支槽分别加强,抑制了西风气流向东推进,使水汽更容易在西南地区西部辐合上升形成降水。结合海表温度分析发现,这种槽脊和反气旋强度变化和太平洋海表温度的变化有重要关系。This paper addresses the relationship between the spring precipitation anomaly in Southwest China and the large-scale atmospheric circulation. In this paper, spring includes March, April and May, and Southwest China includes, Chongqing City, Sichuan Guizhou, and Yun＇ nan Provincel Three categories of datasets from 1961 to 2013 were utilized in the study, including the monthly means of precipitation from 116 meteorological stations in Southwest China, the monthly means of geopotential heights, u-winds, v-winds, vertical velocities, surface pressures and relative humidity from the 2.5°×2.5° NCEP/NCAR reanalysis data, and the 2.0°×2.0° monthly global SST from NOAA Optimum Interpolation Sea Surface Temperature （OISST） analysis. Using these datasets, the vapor flux and the vapor flux divergence were first calculated. Then the spatial distribution characteristics of spring precipitation and SST, characteristics of the water vapor transportation, atmospheric circulation of 500 hPa, wind field of 850 hPa, vertical velocity of 500 hPa, relationship between the spring precipitation and vapor flux, and the relationship between the spring precipitation anomaly in Southwest China and the large-scale atmospheric circulation were analyzed with the EOF, composite analysis and correlation analysis. The results show that the spring precipitation in Southwest China demonstrates a regional consistent rising tendency with a latitudinal dipole mode spatial distribution, i.e., the precipitation in the east of Southwest China （Chongqing, Guizhou, and East Sichuan） and the west of Southwest China （Yun＇ nan and West Sichuan） varies by reversed phase. When precipitation is less than that in normal years in the west but more in the east in spring, Southwest China is impacted by the anticyclone flows from the Indian Ocean and the Pacific Ocean, which benefits the warm moisture water vapor transport from the Indian Ocean and the West Pacific and prompts the increase of precipitation in Southwest China. When precipitation

关 键 词：降水异常 西南地区 春季 EOF 大气环流 

分 类 号：P426.6[天文地球—大气科学及气象学] P434