中国南方地区盛夏高温类型及其对应的大尺度环流和海温异常

利用中国2374个站点的日最高气温资料、NCEP/NCAR大气环流资料以及NOAA海表温度资料，分析了中国南方盛夏高温的主要类型，比较了各类型高温对应的大尺度环流以及与海表温度异常信号的联系。结果表明:中国南方地区年高温日数有明显的增多趋势，利用聚类分析将中国南方盛夏高温分为江淮型、华南型和华中型3类。江淮型高温中心区域位于江淮地区，该类型高温空间范围大、发生频次高，典型的环流系统为高、低空呈现异常反气旋，西太平洋副热带高压（西太副高）偏强偏西，南北位置略偏北。该类型高温是西太副高直接控制下的高温类型，与前冬到夏季中部型厄尔尼诺衰减和春季赤道大西洋地区海温偏高有关。华南型高温中心区域在江南南部到华南地区，典型的环流系统是东亚副热带急流的位置偏南，西太副高偏强、偏西和脊线偏南，华南型高温也是西太副高直接控制下的高温，且伴随着西南季风的减弱，干热特征明显，该类型高温与东部型厄尔尼诺衰减及其与之相联系的印度洋“电容器”效应密切相关。华中型高温主要位于湖北和湖南两省，对应的环流型为西太副高偏弱、偏东，在中高纬度与北大西洋-欧亚遥相关型类似，是大陆高压控制下的高温，使得水汽条件比另两类高温好。北大西洋-欧亚遥相关型是华中型高温的可能信号源。 

Midsummer high temperature types in southern China and corresponding large-scale circulation and sea surface temperature anomalies

Daily maximum temperature data collected at 2374 stations in China, the NCEP/NCAR atmospheric circulation data and NOAA sea surface temperature (SST) data are used to analyze the main types of midsummer high temperature in the southern China. Large-scale circulations corresponding to these high temperature types and their relation with SST anomalies are explored. The results show that the annual high temperature days in the southern China has a significant increasing trend. Cluster analysis is used to classify the midsummer high temperature in the southern China into three types: Jianghuai type, South China type and Central China type. The Jianghuai type high temperature is centered in the Jianghuai area, with a wide range and high occurrence frequency. When the Jianghuai type high temperature occurs, anomalous anticyclone occurs in the troposphere from low to high levels. Meanwhile, the Western Pacific subtropical high (WPSH) is stronger than normal and shifts to the west with the ridgeline located slightly northward. Therefore, Jianghuai type high temperature is a high temperature type under the control of the WPSH. This type of high temperature is mainly related to the attenuation of the central type El Niño from the pre-winter to the subsequent summer and warmer SST in the equatorial Atlantic in spring. The central area of South China type high temperature occurs from the southern Yangtze River basin to South China. The typical circulation systems are the southward displacement of the East Asian subtropical jet, the stronger and westward shift of the WPSH with a southward shift of the ridgeline. Also, the South China type high temperature is directly under the control of the WPSH, accompanied by a weakened southwesterly monsoon circulation. It has an obvious characteristic of dry heat. This type of high temperature is closely related to the attenuation of the eastern type El Niño and its associated Indian Ocean capacitor effect. The Central China type high temperature is mainly located in Hubei province and Hunan province. The corresponding circulation is that the WPSH is slightly weaker and shifts eastward, which shows a similar pattern to the North Atlantic-Eurasia remote correlation pattern in the middle and high latitudes. It is the high temperature under the control of continental high pressure, which makes the water vapor condition better than the other two types of high temperature. The North Atlantic-Eurasian teleconnection is a possible signal source of Central China type high temperature.