北半球环状模和东北冷涡与我国东北夏季降水关系分析

Relationships among the Northern Hemisphere Annual Mode,the Northeast Cold Vortex and the summer rainfall in Northeast China

利用国家气象信息中心提供的1951-2004年全国160个测站月平均降水资料和欧洲中心提供的ERA-40再分析资料，对近50多年东北地区夏季降水、东北冷涡与前期北半球环状模和海温的关系进行了统计分析，定义了一个夏季（6～8月）东北冷涡强度指数（NECVI）。结果表明：NECVI能够较好表征东北低涡的气候效应；夏季东北冷涡强度与降水存在显著的正相关，东北冷涡强年，降水偏多，前期2月北半球环状模（NAW）偏弱；东北冷涡偏弱年，降水偏少，前期2月NAM偏强。此外，夏季东北冷涡与前期的中国近海海温存在显著的负相关，前期NAM和中国近海海温的异常可以作为夏季东北冷涡异常的一个前兆信号，进而为东北地区夏季降水异常的预测提供参考依据。

Based on monthly precipitation and surface air temperature of 160 Chinese stations from 1951 to 2004 supplied by National Meteorological Information Center, the reanalysis data from ERA - 40 datasets supplied by ECMWF with resolution 2.5°× 2.5° and the Reynolds sea surface temperature （SST） data with resolution 2.0°× 2.0°, the correlations among the summer rainfall in Northeast China, the Northeast Cold Vortex （NECV）, the Northern Hemisphere Annual Mode （NAM） and the SST were investigated statistically and a summer （June- August） Northeast Cold Vortex Index （NECVI）was defined. The results demonstrated that there is a significantly positive correlation between the NECV and the summer precipitation in Northeast China. Strong NECV was often associated with more summer precipitation and weak NAM in preceding February, and vice versa. In addition, there was a significantly negative correlation between the summer NECV and the SST in the oceanic areas around China within the preceding months. All these will offer some predictive signals for the NECV and the summer precipitation forecasting in Northeast China.