1961—2020年长湖流域极端降水事件变化特征及其与温度的关系

目的 长湖流域是调控长江中游地区生态平衡的重要湿地生态系统，其降水变化对区域水资源可持续利用和防灾减灾具有重要意义。方法 文章基于1961—2020年长湖流域逐日气象数据，选取9个极端降水指数，运用线性回归分析、相关分析和重标极差分析（rescaled range analysis，R/S）探讨了长湖流域极端降水事件的变化特征及其对气温变化的响应，并预测该区域极端降水事件未来演变趋势。结果 （1）1961—2020年长湖流域年降水量整体呈上升趋势，上升速率为5.4 mm/10年，多年平均降水量为1 151.9 mm；年内降水呈单峰模式，6月的降水量最高，占比为14.99%，12月最低，占比为2.37%。（2）长湖流域极端降水指数均呈上升趋势，除持续湿润日数（CWD）和持续干旱日数（CDD）增加趋势不明显外，其他指数上升趋势显著。（3）CWD和CDD与其他指数的相关性较低，除1日最大降水量（RX1day）与极端降水日数（R95d）相关性不显著以外，其他极端降水指数之间均呈显著相关关系。（4）R/S分析结果表明，未来长湖流域极端降水事件将持续前期的变化趋势。结论 长湖流域极端降水事件总体呈增加趋势，温度上升会对极端降水强度起促进作用。

VARIATIONS OF EXTREME PRECIPITATIOIN EVENTS AND ITS RELATIONSHIPS WITH TEMPERATURE IN CHANGHU LAKE BASIN FROM 1961 to 2020

Changhu Lake Basin (CLB) is a critical wetland ecosystem for regulating the ecological balance of the middle reaches of Yangtze River. The changes of precipitation in CLB have a great significance to the sustainable utilization of regional water resources and prevention and mitigation of natural disasters. Based on the daily meteorological data in CLB from 1961 to 2020, a total of nine indices were selected to represent the extreme precipitation characteristics in this region. The linear regression analysis and correlation analysis was used to examine the variations of extreme precipitation events and its responses to temperature changes. Further, the future trends of extreme precipitation events in CLB were predicted by using rescaled range analysis (R/S). The results were listed as follows. (1) The annual precipitation showed an increasing trend at the rate of 5.4 mm/10a and an annual average precipitation of 1 151.9 mm in CLB from 1961 to 2020. The intra-annual variation of precipitation showed a single peak pattern, with the highest precipitation in June and lowest in December and January, which accounted for 14.99% and 2.37% of the annual total precipitation, respectively. (2) The extreme precipitation indices significant increased (except for CWD and CDD) in CLB from 1961 to 2020. (3) There were low correlations between CWD, CDD and other extreme precipitation indices, while other indices showed significant correlations between each other (except the relationship between RX1day and R95d). (4) The results of R/S analysis demonstrated that the future changes of extreme precipitation events would consistent with the past trends. In summary, the extreme precipitation events show an upward trend during the study period, and with the increasing of temperature, there is an enhancing effect on the intensity of extreme precipitation.