澜沧江流域近51年来极端降水事件的变化趋势和突变特征

基于澜沧江流域1960～2010年31个气象站点的逐日降水资料,采用百分比阈值法定义了不同站点极端降水事件的阈值,应用Mann-Kendall检验方法分析了极端降水事件的降水量、降水频率、降水强度和严重干旱频率等的时空变化特征。结果表明,澜沧江流域极端降水阈值的空间分布呈西北至东南逐渐增大的分布趋势;极端降水事件整体上呈显著上升趋势,且在空间上存在差异,各指标均呈西北向东南逐渐增加的趋势,尤其是德钦站以南的澜沧江中下游地区为干湿事件发生较频繁的区域;极端降水事件在气候的长期变化过程中还存在突变现象。

Sudden Change and Variation Trend of Extreme Precipitation in ancangjiang River Basin during 1960-2010

This study investigates the spatial and temporal patterns of trends of extreme precipitation in the Lancangjiang River Basin for 1960-2010 by using Mann-Kendall trend test on the basis of extreme precipitation thresholds, which are determined for different stations in terms of percentile value. Analysis of changes in four indices of extreme precipitation (extreme rainfall amount, annual number of extreme rainfall, intensity of rainfall and severe drought frequency) in 31 meteorological stations revealed statistically significant increases in the whole watershed. The results show that there is spatial variability in extreme precipitation events, which is described as a positive trend from northwest to southeast in the Lancangjiang River; drought and flood occur more frequently in the south of Deqin station in the lower-middle reaches of the Lancangjiang River; generally, the extreme precipitation has an increasing trend in the Lancangjiang River, but it has sudden change characteristic in the climatic change.