近53年山西极端温度和降水变化趋势分析

Analysis on Trends of Extreme Temperature and Precipitation in Shanxi during 1958-2010

利用山西省国家基本气象观测站1958-2010年逐日最高、最低气温及逐日降水量观测资料,计算分析山西省50多年来极端温度、降水事件的时空变化.研究结果表明,暖日事件频率有明显的增加趋势,其中夏季增加趋势最显著,秋季较弱;冷夜事件有减少趋势,其中冬季减少幅度最大,秋季最小.暖日（冷夜）事件在1995年、1996年前后有突变.山西大部分地区暖日天气增多、冷夜天气减少.但海拔高的山区极端温度变化趋势较小,在人口和经济增长迅速、城市化影响强烈的河谷盆地冷夜事件减少趋势强烈.近50多年平均极端强降水日数有弱的下降趋势,暴雨日数呈明显下降趋势,并有突变现象.极端强降水阈值有空间差异,山西东部山区最大,中部盆地最小.小波变换显示,温度和降水极端事件在全时域上的周期不明显,但局部时域上3～6 a的高频波动较明显.

The daily maximum and minimum temperature and precipitation data during 1958-2010 of the basic standard weather stations in Shanxi Province are used to analyze the change trends of extreme temperature and precipitation.The results indicate that the frequency of warm days show significant increasing trends and the most significant increasing trends is shown in the summer,the least is in autumn.The cool nights show decreasing trends and the most decreasing magnitude is shown in the winter and the least is in the autumn.The abrupt year occurred in about 1995-1996 for the warm days and cool nights.The warm days show increasing and the cool nights show decreasing in the same time in most areas of Shanxi Province.But the changing trend of extreme temperature in the high altitude mountainous area is not significant.The decreasing trend of cold nights event in the valley basin which is strongly influenced by the rapid growth of population and economy as well as urbanization is so obvious.Affected by atmospheric circulation and topography,the thresholds of extreme precipitation have spatial differentiation,the eastern mountain are maximum and middle basin are minimum.Extreme strong rainy days show weakly decrea sing trends.The rainstorm days show significant decreasing trends and saltation.As the wavelet transform shows that the fluctuation of extreme temperature and precipitation events throughout the period of fifty years is not obvious,but the phased periodic vibration is more obvious,specifically with the period of 3～6 years.