上海地区冬季不同等级冷空气变化特征及其对风雨的影响

Climate Characteristics of Winter Cold Air and Its Impacts on Wind and Precipitation in Shanghai in Recent 56 Years

基于1960年12月至2016年2月上海地区地面气象站气温、气压、降水、风速等观测资料,采用趋势分析、相关分析、小波分析、功率谱分析等方法,对冬季影响上海地区不同等级冷空气的活动特征及其对风雨影响进行分析。结果表明:尽管近56 a冬季影响上海地区的冷空气频次未发生明显变化,但所致降温幅度呈现先由大变小、再由小变大的变化特征;冬季中等强度冷空气、弱冷空气次数有14 a和4 a的显著周期;冷空气过程平均最大风速呈明显下降趋势,其中强冷空气平均最大风速下降幅度最大;冷空气降水总量呈增多趋势,弱冷空气降水总量占冷空气所致总降水量的57%。

Based on the observation data from meteorological stations in Shanghai from December 1960 to February 2016,the active characteristics of winter cold air with different intensity grades in Shanghai were analyzed by using methods of tendency analysis,correlation analysis,Wavelet analysis and power spectrum analysis. The results indicated that temperature descending range caused by cold air processes declined firstly and then increased,though there was no obvious change of the total frequency of cold air in Shanghai during the past 56 years. The occurring frequency of moderate and weak cold air had a significant period of 14 and 4 years. The mean maximum wind speed during cold air processes was 7. 7 m·s-1. The total amount of precipitation caused by cold air showed an increasing trend,and the precipitation caused by weak cold air accounted for 57% of the total precipitation caused by all cold air processes.