中文摘要：

利用中国北方269个气象站点1960—2014年逐日平均气温数据,以候均温为统计数据,采用线性倾向估计、Mann-Kendall（M-K）检验、累积距平、Morlet小波功率谱及相关分析等方法,探讨了中国北方严寒期的时空变化特征及其影响因素。结果表明：近54 a来,中国北方各区域严寒期起始候推迟,终止候提前,候数缩短,其中,西北地区起始候推迟最显著,华北地区终止候提前最突出,华北地区候数缩短最长。严寒期空间差异显著,表现为：自南向北,起始候提前、终止候推迟、严寒期延长的趋势更突出;且严寒期变短地区多于变长地区。突变和小波分析表明,北方严寒期在1980s末到1990s初发生了突变,东北、华北和西北地区的严寒期分别存在4.00 a、7.09 a和3.19 a的优势周期。此外,纬度每增大1°,严寒期延长1.30 p;北半球极涡面积指数和亚洲区极涡面积指数是中国北方严寒期变化的重要因素。

英文摘要：

In this study, the spatiotemporal change of cold periods and their affecting factors in north China in recent 54 years were studied based on the daily temperature data and statistical data of pentad mean temperature from 269 meteorological stations in north China during the period of 1960 -2014, using the linear trend estimation, Mann-Kendall （M-K） test, accumulated variance analysis, Morlet wavelet spectra and correlation analysis. The results showed that the start pentads of cold periods were postponed, their ending pentads were advanced, and their durations were shortened in north China in recent 54 years, in which the postponement of starting pentads was the most significant in northwest China, the advancement of ending pentads was the most prominent in north China, and the shortening of cold periods was the longest in north China. The spatial difference of cold periods was significant, that means, from the south to the north, the starting pentads were advanced, the ending pentads were postponed, the postponement of could periods was more prominent, and the regions with shortening of cold periods were more than those with postponement of could period. The mutation and wavelet analysis revealed that the abrupt change of cold periods occurred during the period from the late 1980s to the early 1990s in north China, and there were the dominant periods of 4.00, 7.09 and 3.19 years of cold periods in northeast China, north China and northwest China respectively. In addition, the cold periods were prolonged for 1.30 pentads when latitude was increased by 1 ° ; the indexes of northern hemisphere polar vortex area and of the Asian polar vortex area were the important factors resulting in the change of cold period in north China.