1973—2019年浙江省极端最高气温时空演变特征研究

Spatiotemporal Evolution Analysis on Extreme Daily Maximum Temperature over Zhejiang Province During 1973-2019

极端最高气温是日最高气温变化的上限。基于浙江省66个常规气象站的长序列气温观测资料,分析了浙江区域1973—2019年极端最高气温的时空演变特点,发现全省平均极端最高气温和最大极端最高气温均表现出明显的上升趋势,二者之间存在显著相关,前者在上世纪80年代末~90年代初发生了突变;在空间分布上,多年平均极端最高气温和最大极端最高气温大致呈现自内陆向沿海逐步递减的特征;浙江全省极端最高气温多出现在浙南的丽水市,但从上世纪90年代中后期开始出现在浙北地区(主要是杭州市、绍兴市和宁波市)的年份明显增多;2005年之前全省极端最高气温主要出现在浙西和浙中地区,之后出现在浙东地区的年份显著增多;极端最高气温最易出现在盛夏7~8月特别是7月下旬和8月上旬。在此基础上,进一步探讨了全省极端最高气温出现在浙北、浙中和浙南地区对应的大尺度环流特征以及ENSO不同位相与盛夏极端最高气温出现月份之间的关联,并对拓展研究区域、开展长三角和华东区域极端最高气温研究提出了展望。

Extreme maximum temperature(EMT)can be considered as the upper limit of daily maximum temperature.Spatiotemporal evolution characteristics of EMT in Zhejiang province during 1973-2019 are investigated based on long-term temperature observation at 66 normal meteorological stations.It is found that both the annual provincial-mean EMT(PMEMT)and provincial-highest EMT(PHEMT)displayed distinct increasing trends,and the two correlated well.The PMEMT appeared abrupt change in the short period of 1988-1990.On spatial distribution,temporal-mean EMT and temporal-maximum EMT during 1973-2019 for each station of Zhejiang province both exhibited similar features,with a gradual descending tendency from inland regions to coastal areas.In the time-span of 47 years,PHEMT mostly occurred in Lishui city which located in the southern part of Zhejiang,but after mid-1990 s PHEMT happened in the northern cities of Zhejiang province(Hangzhou city,Shaoxing city,and Ningbo city)more frequently.Before 2005,PHEMT generally resided in western and middle Zhejiang,but subsequently it had more chances to take place in the eastern area.Generally speaking,PHEMT was most likely to occur in mid-summer(July-August)especially the last ten-day period of July and the first ten-day period of August.Besides,large-scale circulation features corresponding to PHEMT occurring in different regions(i.e.the northern,middle,and southern region)of Zhejiang province as well as the relationship between different phases of ENSO and the specific month PHEMT occurred are further discussed.Finally,a suggestion of extending the research region and conducting the Yangtze River Delta and East China EMT study is proposed.