中文摘要：

本文利用1799～1999年的汾河、永定河径流量序列以及PDO序列，采用交叉小波分析法，初步分析了PDO与晋北地区径流量丰枯变化的关系，并在此基础上研究了PDO对晋北径流量的影响机制。结果表明：在多年尺度上，晋北地区径流量与PDO之间存在着明显的反相关关系，即在PDO暖相位时，径流量减少；反之，PDO冷相位时，径流量增大，而且在研究时段内这种反相关关系占主导地位。PDO通过影响副热带高压（简称副高）的强度和位置。从而对晋北地区径流量产生影响。同时，在这一过程中温度也通过蒸发量对径流量产生影响。

英文摘要：

In this article, based on the annual runoff sequence of Yongding River and Fenhe Riv- er. and the sequence of the Pacific Deeadal Oscillation （hereafter referred to as PDO） in AD 1799- 1999, using the spectral analysis which can detect the cyclical changes and their mutual relationship, we preliminarily analyse the relationship between PDO and the change of the runoffs in Northern Shanxi, and further research the mechanism of how PDO affects the runoffs in Northern Shanxi. These sequences indicate that the runoffs in Northern Shanxi had been continuously reducing since the 1920s; this is in accordance with the situation in Shanxi province, which is based on the research of Zhanglihua and reflected by the general decline of the runoffs in North China after the 1920s. Results showed that the runoffs sequence of Lugou bridge and Jingle in the year scale had great instability. However, even though there is no obviously corresponding relationship between PDO and the runoffs of Northern Shanxi in interannual time scale, a significant negative correlation is in exist between them in years of scale, namely when the PDO grows, the runoffs cut; otherwise, the runoffs in- crease, and in the study period, in years of scale the inverse correlation relations is pervasive. Re- search revealed that the change of PDO always result in the change of the strength and location of Western Pacific Subtropical High （WPSH）, which means when PDO decreases, the position of WP- SH is in northeast of China, and the strength is weaker; whereas, when the position of WPSH is in southwest of China, the strength is stronger. The main supply mode of river in Northern Shanxi is precipitation, so when the rainfalls change, the runoffs will be changed. The change of the strength and location of WPSH lead the rainfalls to change, and then the runoffs in the Northern Shanxi have to change. At the same time, the temperature also has an impact on the runoffs through evaporation in this process.