贵州降雨变化趋势与极值特征分析

利用1961—2004年逐日降雨资料,分析了贵州降雨强度、无雨天数、极值降雨的变化趋势及空间分布特征。利用Mann-Kendall法与反距离权重插值法对贵州近44年降雨时空变化趋势进行了分析。利用Gumbel分布拟合最大日降雨量的概率分布特征,并利用极大似然法进行分布参数估计,推求了极端(50年,百年一遇)降雨情形。结果表明,贵州近44年来汛期有雨日降雨强度、最大日降雨量、连续3日、5日、7日无雨的出现频率呈现明显的上升趋势;最大日降雨总体由南向北减少,连续无雨天气出现频率的增加幅度空间分布总体呈东高西低的趋势。

ANALYSIS OF RAINFALL TREND AND EXTREME EVENTS IN GUIZHOU

Temporal variation and spatial distribution of precipitation during 1961-2004 were analyzed on the basis of observed climate data in Guizhou Province.The Mann-Kendall(M-K) test and Inverse Distance Weighting method were used to examine the precipitation trend and describe spatial variation,respectively.Gumbel distribution was applied to daily maximum rainfall,with the parameters estimated by the maximum likelihood method.The extreme values of precipitation with return periods of 50 years and 100 years were then computed on the basis of the density function of Gumbel distribution.The results showed that a significant increase could be seen in annual daily rainfall amount during the raining period,the maximum daily rainfall amount,and times of annual occurrence of successive 3-day,5-day and 7-day no-rainfall periods.Spatially,the maximum daily rainfall amount decreases from the north to the south,and the increasing occurrence of successive no-rainfall periods decreases from the east to the west.