百余年上海冬夏季降水与太平洋海温的相关关系及其年代际差异

利用上海1873—2001年的冬季和夏季降水量与太平洋海温资料，通过计算上海冬季和夏季降水量与太平洋海温的同期和超前相关以及滑动相关系数，讨论上海冬季和夏季降水年代际变化趋势及其与太平洋海温场的相关关系在不同年代和不同空间区域上的显差异．分析发现，上海冬季和夏季的降水均存在明显的年代际阶段性变化，但总体雨量增加的趋势不明显，降水量和太平洋海温的相关关系在不同年代和不同空间区域上存在着显的差异，这种年代际相关关系的差异可能是造成用统计方法做短期气候预测时产生不确定性的主要原因之一．因此作为短期气候预测的常用预报因子之一的太平洋海温场在进行统计预报的应用过程中，适当地考虑在不同时间尺度上的相关差异，将有利于提高预测的准确性和减少统计预测方法中的不确定性．

Correlations Between the Precipitation in Shanghai and Sea Surface Temperature in the Pacific Ocean and Interdecadal Variations

The interannual and interdecadal changes of winter and summer precipitation in Shanghai and the correlations between the precipitation and sea surface temperature on different time scales and in different ocean areas have been examined by using the data of precipitation and the sea surface temperature from 1873 to 2001. The results indicate that there exist obvious interannual and interdecadal variations of the winter and summer precipitation in Shanghai during different periods, in which a rainy period occurs after the 1980s on an interdecadal time scale, with an anomalous precipitation percentage of 150% in winter and summer. The correlation coefficients between the precipitation in shanghai and the sea surface temperature in the Pacific ocean are significantly different on different time scales and in different areas. In summer, a transition in the correlation occurs in the middle 1940s. Before the middle 1940s, there exists a positive correlation between the summer precipitation in Shanghai and the sea surface temperature in the Nino areas during the preceding and the same seasons; after that the correlation changes to negative. In winter, the correlations are different significantly in different seasons, when a positive correlation occurs mainly in summer and autumn and a transition arises in the 1970s. These correlation uncertainties on different time scales possibly lead to instability and inaccuracy in operational climate forecasting, in which the sea surface temperature in the Nino areas is usually used as a predictor. In addition, salient spatial differences in the correlations on the different time scales appear in the Pacific ocean. Thus much more attention should be paid to the correlation differences between the precipitation and sea surface temperature on different time scales and the uncertainties in the climate forecast can be reduced if the correlation differences are considered in statistical forecasting.