贵州省2019年8月极端高温成因分析

Analysis of the Causes of Extreme High Temperature in Guizhou Province in August 2019

该文利用贵州省1960—2019年82个地面观测站逐日最高温度资料,计算1981—2010年极端高温阈值。极端高温阈值分布由东向西递减,赤水最高41.8℃,威宁最低30.0℃,2019年极端高温主要出现在贵阳、黔东南、黔南等地。1960—2019年贵州省极端高温仅在3—9月出现,其中8月最多,3月最少,8月的贡献占全年的48.5%,且2019年8月的极端高温站次数为63次,占2019年的88.7%,比8月的60 a平均高7.5倍。21世纪10年代是极端高温的频发时段,其中2019年8月的极端高温站次数和站次比分别是60 a同期的第3和第2高。2019年8月,贵州上空100 hPa受青藏高压异常北抬东伸控制,500 hPa受大陆副高外围及槽后偏北气流控制,地面有热低压的活动及北上超强台风“利奇马”等影响,导致了极端高温,其中有11个测站最高气温突破历史极值。

Using daily maximum temperatures of 82 ground observation stations from 1960 to 2019 in Guizhou Province,the extreme high temperature threshold from 1981 to 2010 is calculated.It is shown that the distribution of extreme high temperature thresholds decreases from east to west and that the highest temperature in Chishui is 41.8℃and the lowest temperature in Weining is 30.0℃.The extreme high temperature in 2019 mainly occurs in Guiyang,Southeast Guizhou,Southern Guizhou.From 1960 to 2019,the extreme high temperature in Guizhou Province occurred only from March to September,with the most in August and the least in March.The contribution of August accounted for 48.5%of the whole year,and the number of extreme high temperature stations in August 2019 was 63,accounting for 88.7%of 2019,7.5 times higher than the 60-year average in August.The 2010s were a period of frequent occurrence of extreme high temperature,in which the number and ratio of extreme high temperature stations in August 2019 are the third and second highest in the same period of 60 years respectively.In August 2019,the extreme high temperature in Guizhou,in which 11 stations exceeded the historical extreme value,was caused by the abnormal northward and eastward extension of the 100 hPa Qinghai-Tibet high pressure,the 500 hPa continental subtropical high and the northerly airflow behind the trough,the hot low-pressure activity on the ground and the northward super typhoon"Lekima",etc.