1950s以来鄱阳湖流域降水变化趋势及其持续性特征

Long-term trend and persistence of precipitation over Lake Poyang basin since 1950s

以鄱阳湖流域1950 s至2005年10个台站的日降水量为基础,采用距平分析、Mann-Kendall非参数检验对鄱阳湖流域1950 s以来的年、季降水特征和变化趋势进行分析,并以此为基础,结合Hurst指数,从3年、5年、10年三个时间尺度上分析该流域未来降水的变化趋势.结果表明,鄱阳湖流域年内降水分配不均,年际变化较为明显,1960 s、1970 s为偏干年代,1980 s、1990 s为偏湿年代,年降水量在1955-2005年包括一个完整的丰枯过程;近50年来全流域年降水量呈上升趋势,在3种时间尺度上均表现为较弱的持续性,未来降水量可能有小幅度增加;夏冬两季降水量逐渐增加,未来将继续增加,且冬季的增加趋势将比夏季更为显著,夏季降水量长时间尺度上的增加将大于短时间尺度;春秋两季历史降水量呈下降趋势,未来秋季降水量可能继续减少,但趋势不明显,春季降水量在短时间和中时间尺度内变化趋势不确定,在长时间尺度上可能会有小幅度增加.

Based on the daily precipitation data of 10 meteorological stations in Lake Poyang basin from 1950s to 2005,the feature and trends of seasonal and annual precipitations were analysed by using time series anomalies and Mann-Kendall test.On such basis,the future precipitation trend was predicted through Hurst index on 3 different time scales of 3a,5a and 10a.The results showed that： Monthly precipitation of the basin varied obviously throughout the year.Besides,the variations of both annual and decadal precipitation were also observed apparently.The 1960s and 1970s were dry decades,while the 1980s and 1990s were wet decades.In recent 50a,the annual precipitation of the entire basin has increased and shows weak persistence on all the three time scales.So precipitation may increase slightly in the future.As for seasonal cases,precipitations of summer and winter are increasingly rising and will continue to rise in the future.Precipitations will increase even more in winter than summer,and comparatively more on long time scale than on short time scale in summer.On the contrary,precipitations of spring and autumn have been dropping slightly in observed time.In the future,precipitation of autumn would probably continue to drop slightly on all the three time scales.Precipitation variations in spring are uncertain on short and medium time scale,and may slightly increase on the long time scale.