河西地区最大连续降水事件的时空变化特征

Spatio-temporal Probability Behaviors of Maximum Consecutive Wet Days in Hexi Region

选取河西地区13个气象站点1960—2011年逐年日降水资料,采用线性趋势、反距离加权法、Mann—Kendall检验以及R/S分析法,选取4个极端降水指标,分析了河西地区极端降水事件的时空变化特征及未来变化趋势。结果表明,河西地区近52a最大1d降水量和最大2～3d连续降水量呈增加趋势,而最大4d连续降水量呈减少趋势,但变化都不显著。除最大4d连续降水量未来表现为持续性外,其它不同天数最大连续降水未来变化趋势与过去相反。最大1d降水量和最大2d连续降水量与降水总量有很好的相关性,可见最大1d和最大2d连续降水量对降水总量有很好的指示性。在空间分布上,不同天数最大连续降水表现出明显的空间差异,且不同区域的过去和未来变化趋势也不尽相同。研究还发现,在0.05的置信度下,河西地区不同天数最大连续降水发生了明显的突变现象,但突变年份不尽相同。

Based on the daily precipitation data from 13 meteorological stations in Hexi Region during 1960 2011, the methods of linear regression, inverse distance weighted, Mann--Kendall analysis and rescaled range analysis were employed to analyze the spatial and temporal variability of precipitation extremes and predict its extremely precipitation variations in future. Four indices of extreme precipitation were studied. The results showed that over the 1960--2009 period, the regionally averaged occurrence of annual maximum pre- cipitations within 1 d and 2~3 d increased whereas annual maximum precipitation of 4 d decreased. With the exception of annual maximum 4 d precipitation, the predicted trends of the other indices in future were oppo- site compared to the past. The annual maximum 1 and 2 d precipitations correlated with annual total precipi- tation very well, which implies that annual maximum 1 and 2 d precipitations are good indicators for annual total precipitation. The four indices differed substantially in spatial distribution with varying past and future tendencies. In addition, abrupt changes in extreme precipitation indices could be readily identified at the 0.05 confidence level, although they were not the same year.