中文摘要：

基于欧洲中心再分析数据ERA40的海平面气压场和高度场，本文分别采用拉格朗日和欧拉方法研究分析了1958～2001年北半球的不同季节温带气旋活动和风暴路径的年代际变化，以及可能的原因。以客观判定和追踪温带气旋为基础的拉格朗日方法得到了北半球的两个温带气旋主要活动中心，即北太平洋地区和北大西洋／北美地区，同时以500hPa位势高度天气尺度滤波方差为基础的欧拉方法得到了同主要气旋活动中心相吻合的两条风暴轴。研究表明，44年中北大西洋/北美地区温带气旋活动北移加强，以春季最为显著。风暴轴也同样存在着向极移动并加强的特征，并且温带气旋和风暴路径两者移动趋势的相关性很高。作为一个典型地区，北大西洋/北美地区的气旋活动体现了风暴路径的北移，以及温带地区向极地的扩展。但有意思的是北太平洋的情况完全不同，即北太平洋地区的温带气旋活动和风暴轴向低纬度偏移并加强，以春季的南移趋势最为显著。对于此结论，两种方法也有很高的统计相关性。虽然大量研究表明北半球整体上呈现出风暴路径北移的变化特征，但对于具体地区情况有明显差异。另外，400hPa最大Eady增长率和气旋活动频率的经验正交展开函数（EOF）第一模态的空间分布和时间序列非常相似，北太平洋地区和北大西洋地区风暴路径相反的变化趋势很可能同其大气斜压性的同位相的变化有着密切的关系。这也从另一个方面支持了本文对温带气旋和风暴路径年代际变化的分析。

英文摘要：

Abstract Interdecadal variations of extratropical cyclone activities and storm tracks in different seasons for the years of 1958-2001 in the Northern Hemisphere, as well as the possible reasons, are analyzed by applying the Lagrange and Euler methods to the sea-level pressure and height fields from the European Center for Medium-Range Weather Forecasts reanalysis data ERA40. With the Lagrange method based on detecting and tracking extratropical cyclones, two main cyclone activity centers are got, i.e., the North Pacific and the North Atlantic/North America. At the same time, with the Euler method based on the synoptic scale variance for 500 hPa geopotential height, two storm tracks are obtained, which are in accordance with two main cyclone activity centers. The result shows that extratropical cyclones in the region of the North Atlantic/North America in the 44 years moved northward and intensified, especially in spring. Also, there was a feature with a poleward shift and increasing strength for the storm track. High correlation was observed between the movements of extratropical cyclones and the storm track. The North Atlantic/North America is a typical region, where cyclone activities reflected the northward movement of the storm track and the poleward expansion of temperate zone. However, it is interesting to find that the situation in the North Pacific is just the opposite, i.e., extratropical cyclones and the storm track migrated to the lower latitudes with enhanced intensity, especially in spring. For this conclusion, two methods are also statistically correlated. The storm track over the whole Northern Hemisphere had a poleward shift by some studies, but obvious differences were found in specific areas. Besides, the space distributions and time series of the first empirical orthogonal function （EOF） mode of the maximum Eady growth rate and cyclone activity frequency are similar. There may be a close relationship between the opposite trends of storm tracks in the North Pacific and the North Atlantic and