1960—2011年甘肃河东地区极端降水变化

Extreme Precipitation in 1960-2011 over Hedong Area of Gansu,China

选取甘肃河东地区13个气象站点19602011年的日降水资料，运用气候线性趋势、Mann-Kendall检验、Morlet小波分析、反距离加权法和R／S方法，分析了甘肃河东地区极端降水的时空分布，并预测了未来变化趋势。结果表明：（1）河东地区近52年持续干旱日数呈显著增加趋势，而其余极端降水指标呈减少趋势，其中只有中雨日数通过了显著性检验；各极端降水指标在河东季风区和河东高寒区存在明显差异；在河东季风区，中雨日数、R95极端降水量和降水强度显著减少，而持续干旱日数显著增加；在河东高寒区持续降水日数显著减少。（2）空间分布上，除持续干旱日数大多数区域增加外，其余极端降水指标大部分区域减少，减少区域集中在河东中部和河东东南部。（3）极端降水指标主要以20年和5～8年的周期为主，在不同的时间序列信号强弱不同。（4）中雨日数、持续干旱日数、R95极端降水量、降水强度在20世纪70年代发生趋势性突变，持续降水日数和最大5天降水量在80年代转折性突变。（5）除中雨日数、持续降水日数在河东高寒区未来发展不稳定外，其它各指标在各区域未来表现出持续性，与过去变化趋势一致。

Based on daily precipitation data collected in 13 meteorological stations over Hedong area of Gansu Province, China during 1960-2011, the method of linear regression, inverse distance weighted interpola tion, MannKendall test, wavelet analysis and rescaled range analysis are employed to analyze the spatial and temporal variability of extreme precipitation, and the trend of extreme precipitation is also predicted. The results are as follows： （1） During 1960 -2011, consecutive dry days have significantly increasing trend. The other indices decrease and only heavy precipitation days decrease significantly at the 0.05 level. There are obvious differences between monsoon subarea and plateau subarea. In monsoon subarea, heavy precipitation days, very wet day precipitation and precipitation on wet days have significantly decreasing trends, whereas consecutive dry days increase significantly. In plateau subarea, consecutive wet days have asignificantly decreasing trend. （2） Spatially, for consecutive dry days, most of places display increasing trends. The other indices show decreasing trends, mainly concentred in the middle and southeast of He dong. （3） The departure sequence vibration of the extreme precipitation indices is quasi20 years and 58 years. At the same time, the extreme precipitation indices reflect different structures which are more or less in different time scales. （4） For heavy precipitation days, consecutive dry days, very wet day precipita tion and precipitation on wet days, the abrupt change is discovered in the 1970s, whreras the abrupt change of consecutive wet days and maximum gday precipitation happen is in the 1980s. （5） In the plateau subare a, the variation of heavy precipitation days and consecutive wet days is not stable in future. Compared to the past, the other indices are consistent with patterns in future.