西安市降水频率变化特征分析  

Characteristic analysis of change in precipitation frequency in Xi'an City

作　　者：杨新[1] 

机构地区：[1]北京师范大学全球变化与地球系统科学研究院,北京100875

出　　处：《自然灾害学报》2011年第4期60-65,共6页Journal of Natural Disasters

摘　　要：利用1951-2005年西安市的逐日降水资料,分析了西安市降水量和降水频率的年、季变化特征,探讨了各等级降水的频率变化对总降水量变化的贡献。结果表明:(1)50多年来西安市降水量有所减小,降水日数显著减少且在春夏秋冬四季均有反映,降水日数的减少速率以秋季为最大;(2)5mm以下小雨的降水频率有显著的逐年代降低趋势,而5～10mm的小雨和中雨的降水频率基本上没有变化,大雨和暴雨及以上的降水频率低,且其变化具有随机性;(3)自20世纪80年代以来,春夏秋冬四季的小雨降水频率均有所降低,其中夏季小雨降水频率的减少系主要由微量降水雨日的减少引起;(4)小雨降水的频率比重和总量比重自20世纪80年代以来显著降低,中雨降水总量比重也有所降低,而大雨和暴雨及以上的降水量比重基本没有变化。所以小雨和中雨降水总量减少是多年来总降水量减少的主要原因。研究结果显示,人类活动排放的气溶胶可能是造成西安市降水频率降低和总量减少的主要原因之一。Based on the daily precipitation data of Xi'an in 1951-2005,the study analyzed the long-term trends of precipitation probability and amount not only in all year but also in four seasons respectively.The results show that(1) Total precipitation amount has a decreasing trend in the last fifty years.The number of precipitation day has a significant decreasing trend not only for all year but also for four seasons,and the fastest decreasing rate occurs in autumn.(2) The probability of light rain less than 5mm has a significant decreasing trend while the probability of light rain with 5~10 mm has no change in the studied period.There is no change trend in the probability of moderate rain and the more.(3) The probability of light rain in the four seasons has decreased since 1980s.While the probability change of light rain in summer is induced by decrease of drizzle day.(4)The proportion of light rain both in probability and in amount decreases distinctly.The amount proportion of moderate rain decreases a little while that of heavy rain has no decrease trend.Therefore the decrease in amount of both light rain and moderate rain contributes mostly to the decrease in total annual precipitation amount.All the results strongly indicate that the aerosol exhausted by human activities is one of possible main reason for the decrease of amount and probability of precipitation in Xi′an.

关 键 词：降水 频率 变化 西安市 

分 类 号：P426.6[天文地球—大气科学及气象学]