长江中下游夏季降水异常变化与若干强迫因子的关系

首先,利用三次样条函数方法对1905～2000年长江中下游夏季降水量和太阳黑子、地球自转速率、赤道东太平洋海温和北极涛动等强迫因子序列进行年代际和年际尺度的分离,并分析了它们年代际尺度的位相变化特征.然后,使用30年滑动相关的方法,分析了长江中下游夏季降水量与上述各因子之间的相关随时间的变化.最后,利用旋转因子分析方法,对年代际及年际尺度因子的潜在结构对长江中下游夏季降水的影响进行了研究.结果表明,长江中下游夏季降水量和强迫因子序列均存在显著的年代际变化特征,它们之间的相关系数随时间变化呈现显著的阶段性,

Relationships Between Precipitation Anomaly over the Middle and Lower Reaches of the Changjiang River in Summer and Several Forcing Factors

The interdecadal components and the interannual components of the precipitation over the middle and lower reaches of the Changjiang River in summer and forcing factors,such as the relative sunspot,earth's rotation speed,sea surface temperature in the equatorial eastern Pacific and arctic oscillation during 19052000,are separated by using the third splines firstly and then the characteristics of interdecadal variation are analyzed.By using the method of 30-year moving correlation,the temporal variation of relationships between the precipitation and the factors is studied.In addition,the effect of the potential structure of factors with interdecadal scale and interannual scale on the precipitation anomaly is analyzed by the rotated principal component analysis.The results show that the variation trends of the interdecadal scale of the precipitation over the middle and lower reaches of the Changjiang River in summer and the above factors are all obvious and the relationships between the precipitation and the factors are generally unstable,which the phase of correlation coefficients with temporal change were significant,even the signs of phase have changed.The precipitation anomaly in the middle and lower reaches of Changjiang River in summer is influenced by two kinds of potential factor structures that are composed of factors with interdecadal scales and interannual scales respectively.In the former the contribution of the interdecadal change of the relative sunspot,earth's rotation speed and arctic oscillation is greater to the abnormal precipitation,in which the action of the sunspot is the most significant.The influence of factors with the interdecadal scale on the precipitation anomaly have got a raise after the 1940s.In the latter the contributions of the interannual change of sea surface temperature in the equatorial eastern pacific in the previous autumn and present summer and arctic oscillation in the previous winter and spring are greater.