鄱阳湖流域极端降水时空变化特征及ENSO事件影响分析

Spatiotemporal Variations of Extreme Precipitation and the Influence of ENSO in the Poyang Lake Basin

基于鄱阳湖流域29个气象观测站1960~2017年逐日降水资料,选用11个极端降水指数,采用趋势分析、突变检验、相关分析和小波分析等方法,系统研究了鄱阳湖流域极端降水的气候背景和时空变化特征,探讨了不同海区ENSO事件与极端降水变化的响应关系。结果表明,鄱阳湖流域自1990s以来流域气温上升趋势显著,降水年代际波动特征明显。在年际变化上,主要极端降水指数大多呈不同程度的上升趋势,并在1990年前后发生突变。空间上,流域极端降水指数总体上呈东北向西南减小态势,大多数指数在流域中南部增加趋势相对突出。流域极端降水与NINO 1 + 2区之间的线性相关最为显著。在2~6 a时间尺度上,流域极端降水与4个海区海温异常指数之间存在共振周期,2010年之后,鄱阳湖流域降水与赤道太平洋海温异常的同位相变化(正相关)关系明显增强。此外,当ENSO处于暖事件时,鄱阳湖流域绝大多数区域年总降水量均表现为不同程度的增加。本文的研究结果对于科学认识和了解鄱阳湖流域洪涝灾害的复杂背景和产生机制具有重要的理论与现实意义。

In this study, 11 extreme precipitation indices were selected to examine the spatiotemporal variation of extreme precipitation in the Poyang Lake basin during 1960~2017. The responses of extreme precipitation indices to ENSO events of different areas of the Pacific Ocean were further investigated. The results show that the temperature in the Poyang Lake basin increased significantly since the 1990s, and the inter-decadal precipitation fluctuated obviously. Most extreme precipitation indices showed that an upward trend with abrupt changes occurred around 1990. Spatially, the extreme precipitation indices decreased from northeast to southwest. The increasing trend of most indices in the central and southern part of the basin was relatively prominent. The linear correlations between the extreme precipitation indices and NINO 1 + 2 were the most significant. On the timescale of 2~6 years, a common oscillation period between the extreme precipitation of the basin and the four ENSO indices can be observed. After 2010, the positive correlation between the precipitation of the Poyang Lake basin and the SST anomalies in the equatorial Pacific increased significantly. Additionally, when in a warm ENSO year, annual precipitation in most areas of the Poyang Lake basin increases in varying degrees. The results of this study will improve the understanding of the complex background and driving mechanism of flood disasters in the Poyang Lake basin.