东北夏季降水的时间变化特征及其与太平洋海温的相关关系

利用中国降水逐日站点观测资料以及HadISST海温资料,分析了1961-2010年东北地区70个观测站夏季降水的变化特征以及太平洋海温对东北夏季降水的可能影响。结果表明：东北夏季降水近50a来呈现下降趋势,具有多阶段性,在60年代以及80-90年代存在明显的突变；在1986-1985年以及1986-2010年2个阶段,热带外太平洋与热带太平洋春季和夏季海温都存在与东北夏季降水的相关关键区,两个阶段相关性显著不同甚至相反,是1961-2010年东北夏季降水与太平洋海温总体相关性较弱的原因。东北夏季降水与太平洋海温的相关性可能与海温冷暖背景有关系：在暖的海温背景下,东北降水与热带太平洋海温呈现显著的正相关；而对于热带外太平洋,暖的海温背景下,两者为负相关,冷的海温背景下,两者为正相关,尤其表现在春季,因此太平洋春季海温异常对于东北夏季降水预测有较好的指示意义。

Variation characteristics of the summer rainfall in North-east China and its correlation with the sea surface temperature in Pacific

In this paper, the daily observed rainfall and the HadISST data are used to study the characteristics of the summer rainfall variations in North-east China and its correlation with the Pacific sea surface temperature (SST) from 1961 to 2010. The results show that in the last 50 years, the summer rainfall in the North-east China clearly has a decreasing trend; by the abrupt change detecting with Mann-Kendall test, the rainfall has sudden changes in 1965 and the period of the mid of 1980s to 1990s. From 1961 to 2010, the correlation coefficients between the rainfall and the SST in Pacific are not notable, especially in the subtropics. Compare the correlation coefficients in the first period (1961-1985) to that in the second period (1986-2010), the correlation results are very different, and even they are opposite. Further analysis of the correlation characteristics between the rainfall and the SST in extropics and tropics indicates that the correlation coefficients are positive between the rainfall in North-east China and tropical Pacific SST when the SST is positive anomaly; as for the subtropical Pacific, the warm SST corresponds to the negative correlation coefficients, and the cold SST corresponds to the positive correlation coefficients, especially in spring. Thus, the spring SST in Pacific may be an index to forecast the rainfall in North-east China.