1955—2007年拉萨市雨季夜雨率变化特征

摘要

Using daily precipitation and air temperature data of Lhasa to analyze the night-rain rate in rainy season（May-September） during years 1955-2007,the results could be summarized as follows：The variations of night-rain rate was comparatively stable in whole rainy season,without obvious inter-decadal changes during the past 50 years.The night-rain rate was significantly associated with daily precipitation, and the night-rain rate increased with the enhancement of precipitation when rainfall was below 25 mm,it was the minimum 75.2%when daily rainfall was below 1 mm,and it was the maximum 93.4%when daily rainfall was 25 mm.There is a significantly negative correlation between night rain rate and daily temperature. In the meantime,the night-rain is related with the terrain.The high night-rain rate has its advantageous aspect,but also it will bring some negative influences.%利用1955—2007年拉萨市逐日降水和气温地面观测资料,分析了拉萨市雨季（5—9月）夜雨率变化特征。结果表明：拉萨市整个雨季日夜雨率变化是比较稳定的,近50多年来基本没有发生明显的年代际变化。夜雨率与日降水量有显著关联,当日降水量在25 mm以下时,夜雨率随降水量增加而增大,当日降水量〈1 mm时夜雨率最小为75.2%,当日降水量为25 mm时,夜雨率达到最大值93.4%;夜雨率与日温差存在显著的负相关;拉萨多夜雨与地形有关,高夜雨率既有有利的一面,也会带来一些负面影响。因此,深入探讨夜雨率是制定有效防御气象灾害对策的重要依据。