东江流域降水时空变化及其与ENSO事件的响应关系

Study on Spatial-temporal Characteristics of Precipitation and Response Relationship of ENSO Events in Dongjiang River Basin

为了解东江流域降水的时空变化特征,揭示气候变化对流域降水变化的驱动关系,采用去趋势预置白Mann-Kendall检验、直线回归滑动平均、交叉小波等方法分析了东江流域1959~2018年降水时空特征,并揭示其与ENSO事件的响应关系。结果表明,东江流域近60年来降水以-4.29mm/10a的幅度缓慢减少,年内分布不均,属夏季降水最多,占年降水总量44%;各季节降水变化不一,春、秋两季在缓慢减少,夏、冬两季则在缓慢增加。汛期降水占年总量79%,以-10.6mm/10a的幅度减少;非汛期降水以6.1mm/10a幅度增加。空间上降水地域差异性明显,汛期降水与年际降水呈现由中游向上游、下游逐渐递减的分布;非汛期降水则呈现由上游向下游递减的带状分布;降水与ENSO事件响应关系显著,主要表现在1970年代2~4年周期与1990年代后期3~6年周期尺度上,表明气候变化是目前降水变化的主要驱动因子。

Based on the daily precipitation data during the period of 1959-2018,trend-free pre-whitening Mann-Kendall(TFPW-MK)test,linear regression moving average(LRMA)method and the cross wavelet transform method were used to analyze the spatial-temporal variation characteristics of precipitation and the driving relationship between ENSO events and precipitation change in Dongjiang River Basin.The results show that the annual precipitation in Dongjiang River basin has been decreasing slowly with the amplitude of-4.29 mm/10 ain the past 60 years.The precipitation is distributed unevenly in the year,among which the precipitation amount in summer accounts for 44%of the total annual precipitation.In terms of precipitation changes in different seasons,the variation trend of precipitation in each season is inconsistent,which shows a decreasing trend in spring and autumn and an increasing trend in summer and winter.Moreover,the precipitation in flood season accounts for 79% of the annual total precipitation and decreases by-10.6 mm/10 a,while the precipitation in non-flood season increases by 6.1 mm/10 a.The difference of the spatial distribution of precipitation is relatively obvious.It shows that the precipitation gradually decreases from the middle to the upstream and the downstream in the flood season and during the whole year.And the precipitation in non-flood seasons shows a band distribution decreasing from upstream to downstream.Furthermore,the precipitation and ENSO events are significantly correlated,which is mainly manifested in the cycle of 2-4 years in the 1970 sand the cycle of 3-6 years in the late1990 s,which indicates that the climate change is the main driving factor of precipitation in Dongjiang River basin.