50年来灞河流域降水变化特征分析

为了更加深入地了解灞河流域气候变化特征,利用灞河流域近50 a的降水观测数据,运用滑动平均法、R/S分析法、Mann-Kendall突变检验法及小波分析法分析了灞河流域年内、年际降水的变化趋势、突变时间及降水的变化周期。结果表明:1958—2012年降水呈波动下降趋势,未来几年降水仍然呈下降趋势;年内降水分配极不均匀,主要集中在7—9月份,春季和秋季降水呈明显下降趋势,夏季和冬季降水呈微弱上升趋势;四季降水Hurst指数均0.5,降水序列具有反持续性和负相关性;年降水有明显突变特征,突变时间为1989年,春、夏和秋季有明显的突变点,突变时间分别为1994,1979,1985年,冬季降水无明显突变点;年降水及四季降水序列的变化周期基本在22~29,13,4~8 a的时间尺度上浮动,不同尺度上周期性变化差异较大。

Characteristics of Precipitation Variation ofBahe River Basin in the Past 50 years

The aim of the present research is to better understanding the characteristics of climate change in the Bahe river drainage basin.The annual and inter-annual precipitation changes, the abrupt change time, and the variation period of precipitation are analyzed based on observations in the past half century.Moving-average method, R/S analysis, Mann-Kendall test, and wavelet analysis are adopted for the research.Results reveal that 1) from 1958 to 2012, precipitation presented a decline trend with fluctuations, and will keep declining in the next several years;2) precipitation is extremely uneven in a year, mainly focused from July to September, decreasing obviously in spring and autumn, and rising slightly in summer and winter;3) Hurst index of precipitation in four seasons are all less than 0.5, and the precipitation series have features of anti-continuity and negative correlation;4) annual precipitation has apparent abrupt change in 1989, and abrupt changes are also found in the spring, summer and autumn in 1994, 1979, and 1985, respectively, with no abrupt change in winter;5) the variation period of annual and seasonal precipitation fluctuates in time scales of 22-29 a, 13 a, and 4-8 a, and the periodic change differs greatly in various scales.