长江三角洲地区极端气温事件变化特征及其与ENSO的关系

摘要

基于1960-2014年65个气象站点逐日最高、最低气温和平均气温资料,分析了长江三角洲地区极端气温事件的变化规律和ENSO事件强度对极端气温指数变化趋势的影响.结果表明:近55年长江三角洲地区夏季日数(SU)、热夜日数(TR)、暖昼日数(TX90)、暖夜日数(TN90)、异常暖昼持续指数(WSDI)、生长期(GSL)均呈增加趋势,其中暖夜日数(TN90)增加幅度最大,增幅为8.55d/10a;极值指数也呈上升趋势,其中月最低气温极小值(TNn)上升幅度最大为(0.53℃/10a);冰冻日数(ID)、霜冻日数(FD)、冷昼日数(TX10)、冷夜日数(TN10)、异常冷昼持续指数(CSDI)均呈减少趋势,其中冷夜日数(TN10)减少幅度最大(-6.06d/10a);月平均日较差(DTR)以0.11℃/10a的速率呈下降趋势.空间上,所有站点SU、TXn、TNx呈增加趋势;TR、TX90、TN90、TNn、TXx、WSDI、GSL分别有97％、85％、98％、95％、78％、92％、94％的站点呈增加趋势;所有站点ID、FD、TX10、TN10呈减少趋势;CSDI、DTR分别有87％、77％的站点呈减少趋势.多数极端气温指数与纬度、经度、海拔显著相关.气候变暖突变后,极端暖指数明显增加,极端冷指数明显减少.总体上,厄尔尼诺对极端气温指数的影响大于拉尼娜的影响.%Based on daily temperature (maximum,minimum,and average) data of 65 stations,spatial and temporal changes of extreme temperature events and the E1 Ni（n）o Southern Oscillation (ENSO) influence on the extreme temperature threshold over Yangtze River Delta were analyzed for the period 1960-2014.The results showed that in the last 55 years,the extreme temperature indices,i.e.summer days (SU),tropical nights (TR),warm days (TX90),warm nights (TN90),warm spell duration days (WSDI),and growing season length (GSL) have all increased significantly,and TN90 showed an increasing rate of 8.55d per decade.The extremal indices (TXn,TNn,TXx,and TNx) had increasing trends in the Yangtze River Delta region,and TNn showed an increasing rate of 0.53℃ per decade.The ice days (ID),frost days (FD),cold days (TX10),cold nights (TN10),and cold spell duration days (CSDI) have decreased significantly by 0.40 d,4.03 d,2.56 d,6.06 d and 0.33 d per decade,respectively,and TN10 showed a decreasing rate of 6.06 d per decade.DTR has decreased by 0.11 ℃ per decade.For the spatial distribution of SU,TXn and TNx,all meteorological stations showed increasing trends during 1960-2014.TR,TX90,TN90,TNn,TXx,WSDI,and GSL showed increasing trends at 97％,85％,98％,95％,78％,92％,and 94％ of meteorological stations,respectively.ID,FD,TX10,and TN10 showed decreasing trends for all stations.For CSDI and DTR,87％ and 77％ stations showed decreasing trend.Most extreme temperature indices show good correlation with latitude,longitude,and altitude.After the detected abrupt climate changes,extreme warm indices increased,and extreme cold indices decreased significantly.Overall,the effect of E1 Ni（n）o on extreme temperature indices was greater than the effect of La Nina.