华北夏季降水异常与大气环流和海温的关系
The Relationship between Summer Precipitation Anomaly in North China, Atmospheric Circulation and SST
中文摘要：
利用1961—2015年中国地面气象台站格点化降水资料、NOAA提供的逐月海表温度资料，以及NCEP/NCAR月平均再分析资料，采用EOF、相关分析和合成分析等方法，分析了华北夏季降水与大气环流和海温的关系以及冬季EP型El Ni?o指数（IEP）对华北次年夏季降水的影响。结果表明：华北夏季降水偏多（少）年的环流特征为贝加尔湖地区位势高度负（正）距平，北太平洋存在一位势高度正（负）异常中心，日本海到渤海正位势高度距平加强（减弱），表现为东亚地区典型的东高（低）西低（高）的环流形势；同期夏季在赤道中东太平洋存在关键区海温异常，与华北夏季降水呈显著负相关关系，表明关键区海温增暖（变冷），华北夏季降水减少（增加）；冬季IEP指数正位相年华北次年夏季降水正异常，西北太平洋上空500 hPa位势高度显著负异常，中高纬呈现两脊一槽型环流形势，西太平洋副热带高压位置较气候态偏西，赤道西太平洋为明显的异常东风，低层垂直上升运动为孟加拉湾经向通道和太平洋纬向通道的水汽输送提供有利动力条件，有利于华北雨季降水偏多；IEP指数负位相年环流形势则相反。
中文关键词：
华北夏季降水，EP型El Niño指数，太平洋海温，大气环流
KeyWords：
summer precipitation in North China, EP type El Niño index, the Pacific sea surface temperature, atmospheric circulation
Abstract：
Using the gridded precipitation data from Chinese ground meteorological stations, the NOAA monthly sea surface temperature (SST) data, and the NCEP/NCAR monthly mean reanalysis data from 1961－2015, and with EOF, correlation analysis, and synthetic analysis, we analyze the relationship between summer precipitation, atmospheric circulation and SST in North China, as well as the influence of the winter EP-type El Ni?o index (IEP) on summer precipitation in North China in the following year. The results show that the circulation characteristics of the increased (decreased) summer precipitation in North China are negative (positive) geopotential height anomaly in Lake Baikal, a positive (negative) anomalous center in the North Pacific Ocean, and a strengthening (weakening) positive geopotential height anomaly from the Sea of Japan to the Bohai Sea, which is typical of the east-high (low) west-low (high) circulation in the East Asian region. There is an anomaly of key SSTs in the east-central equatorial Pacific Ocean in the same period of summer precipitation in North China, exhibiting a significant negative correlation, which means that the increased (decreased) SST in the key area is correlated to the decreased (increased) summer precipitation in North China. Positive phase years of winter IEP index are accompanied with positive anomaly of summer precipitation in North China in the following year, while significant negative anomaly is identified at 500 hPa over Northwest Pacific Ocean. The circulation type of two ridges and a trough type appears in the middle and high latitudes. The subtropical high pressure in the western Pacific Ocean shifts more westward than the climatic state. Obvious anomalous easterly wind is found in the equatorial west Pacific. The vertical uplift movement in the low level provides favorable dynamic conditions for the transport of water vapor in the meridional channel of the Bay of Bengal and the latitudinal channel of the Pacific Ocean, which is conducive to the increased precipitation in the rainy season in North China; The opposite situation occurs in the negative phase years of the IEP index.