河西走廊春季降水的空间异常分布及年代际变化

利用河西走廊19个气象站建站至2012年3—5月降水量资料,分析了河西走廊春季降水的基本气候特征;通过EOF、REOF、小波分析等方法,对河西走廊春季降水的时空特性进行了研究,用Mann-Kendall检验法检验河西走廊春季降水序列是否存在突变现象。结果表明,河西走廊春季降水空间分布极不均匀,其空间分布特征是东南部为多雨区,西北部为少雨区。河西走廊春季降水在第一空间尺度上为全区一致,在第二空间尺度上可分为2个自然气候区,在第三空间尺度上可分为5个自然气候区。从年代际变化来看,21世纪初10年是近半个世纪来降水最多的10年,20世纪70年代是降水最少的10年;河西走廊春季降水的年际变化十分显著,降水最多的年份是最少年份的6倍多。1961—2012年间河西走廊春季降水发生了明显的突变:1985年出现了一次趋于增多的突变。3年的短周期和19年的长周期是其主要周期。

Abnormal Spatial Distribution of Spring Precipitation and Its Decadal Variability in the Hexi Corridor in the Arid Area of Northwest China

Using the precipitation data of 19 meteorological stations in the Hexi Corridor through 2012, we analyzed the climatic character of spring precipitation. EOF, REOF and power spectrum method were used to research the spatial and temporal characteristics of spring precipitation. Whether there was mutation in the spring precipitation sequence was tested by Mann-Kendall way. The results showed that the spatial distribution of spring precipitation in the Hexi Corridor was extremely uneven, the rainy area was located in the southeast, and the less rain area was located in the northwest. The spring precipitation was consistent in the entire region at the first space scale, and two natural precipitation zones at the second spatial scale, and five natural precipitation zones at the third spatial scale. The 2010s was a decade with the most precipitation for nearly half a century. The precipitation was the least during 1970s. The annual variability of the spring precipitation was significant in the Hexi Corridor. The year with the most precipitation was 6 times more than the least year. There was obvious mutation in 1985 for the spring precipitation in the Hexi Corridor from 1961 to 2012. Short period of 3 years and long period of 19 years were the main cycle.