鄱阳湖流域1960～2018年极端气温变化及其与大气环流的关系

为进一步揭示鄱阳湖流域极端气温事件变化及其影响因素,基于鄱阳湖流域24个气象站点连续59年观测资料,选取8个极端气温指数,分析鄱阳湖流域极端气温动态变化,并探讨了大气环流与极端气温变化的联系.结果表明:(1)鄱阳湖流域极端气温暖指数(暖昼天数、暖夜天数和夏日天数)及极值指数(日最低气温最小值和日最高气温最大值)均呈增加趋势;冷指数(冷昼天数、冷夜天数和霜冻天数)均呈逐渐减少趋势.(2)从空间分布来看,极端气温空间变化趋势与年际变化一致,极端气温暖指数和极值指数呈增加趋势,冷指数均呈减少趋势,但在不同地区变化趋势存在差异.流域各站点霜冻天数和冷昼天数均呈显著下降趋势,但在赣北地区下降趋势最显著.大部分站点(23/24)暖夜天数、夏日天数和日最低气温最小值均呈显著增加趋势;(3)鄱阳湖流域极端气温指数的变化与大气环流的变化存在相关性,其中西太平洋副高强度指数、夏季东亚季风指数、亚洲区极涡强度指数和北极涛动指数对极端气温事件影响显著.研究结果可为极端气候风险评估、灾害预警提供参考.

Variations of Temperature Extremes in Poyang Lake Basin and Its Association with Atmospheric Circulation

Understanding dynamic changes in climate extremes is important in forecasting extreme climate events and reducing their associated impacts. The objectives of this study were to analyze the spatiotemporal variations in temperature extremes and their association with atmospheric circulation, based on daily maximum (TX) and minimum temperatures (TN) collected from 24 meteorological stations in the Poyang Lake Basin (PLB) from 1960 to 2018. Eight extreme temperature indices were used to quantify temperature extremes. The Mann-Kendall method and linear trend analysis were used to examine the trends, and Pearson correlation analysis was used to analyze the correlation between the temperature extremes and each atmospheric circulation. The results showed that: warm indices, including the number of warm nights, warm days, and summer days, and extreme indices, including minimum TN and maximum TX, showed increasing trends in the PLB from 1960 to 2018; on the other hand, cold indices, including the number of cold nights, cold days and frost days, showed decreasing trends; The spatial variation of temperature extremes were similar with its temporal variations, which shows that warm indices and extreme indices increased, whereas cold indices decreased. On the other hand, the variations of temperature extremes were differences in different regions. The decreased trends of the number of frost days and cold days were more significant in the northern of PLB than other part of the basin. The number of warm night days, summer days and minimum daily minimum temperatures increased significantly in most stations (23/24); Variations of temperature extremes were related to the changes of atmospheric circulations. Western Pacific Subtropical High Intensity Index, the summer East Asian monsoon, the Asian Polar Vortex Intensity Index and the Arctic Oscillation showed significant correlations with temperature extremes. These findings will provide reference information in forecasting extreme climate events and taking measures to reduce their associated impacts.