近50 a甘肃省夏季日极端降水频数与强度变化特征

基于甘肃省近50 a夏季日降水量数据，借助ArcGIS 9.2和Matlab 7.0数据软件平台，运用复值Morlet小波分析及Mann kendall检验法，分析甘肃省夏季日极端降水频数和强度的周期及空间分布特征。结果表明：① 极端降水频数主要存在19 a和8 a周期，极端降水强度主要存在11 a和19 a周期；② 夏季极端降水量与夏季降水量的空间分布在东南部地区有明显的差异；③ 极端降水频数呈减少趋势，而极端降水强度呈增加趋势。

Analysis on Change of Daily Extreme Precipitation Frequency and Intensity in Gansu Province in Summer during the Period of 1959-2008

In this paper,the changes of periodic and distributional characteristics of daily extreme precipitation frequency and intensity in summer were analyzed using the ArcGIS and Matlab 7.0 data software platform,complex Morlet wavelet analysis and Mann-Kendall test based on the data of daily precipitation in Gansu Province in summer during the period of 1959-2008.The results show that there were mainly the 19-year and 8-year periodicities of extreme precipitation frequency and mainly the 11-year and 19-year ones of extreme precipitation intensity.There were also the obvious differences in extreme precipitation and spatial distribution of total precipitation in summer in the southeastern region of the province.Moreover,the extreme precipitation frequency was in a decreasing trend,but the extreme precipitation intensity was in an increasing trend.