遥相关型对我国西南地区高温热浪天气的影响

Effect of Teleconnection Type on High Temperature Heat Wave Weather in Southwest China

摘要: 为了进一步研究遥相关型对我国西南地区高温热浪天气的影响，本文利用中国西南地区148个气象站1979~2019年6~8月的逐日最高气温数据和NCEP/NCER的月平均位势高度场再分析资料，以6~8月500 hPa平均位势高度场作为夏季平均高度场，通过自然正交函数(EOF)分解得到西南地区高温热浪的时空分布特征，再分别对东亚–太平洋(EAP)遥相关型典型正负异常指数年的500 hPa位势高度场相对于1979~2019年夏季气候平均高度场作合成分析。结果表明：1) 总体看来，西南地区高温热浪次数分布东多西少，重庆为高温热浪次数大值区。2) 西南地区高温热浪次数具有整体增多的趋势，近几年都在增加但变化幅度不大，但是2006年是明显增多的异常年份。而且其空间分布具有明显的东西差异，在四川东部和重庆地区为大值区，其次是贵州和广西大部分地区，云南高温热浪次数较少。3) EAP遥相关型的年代际变化不明显，其主要是以年际变化为主的。EAP指数典型正负异常年的大尺度环流场具有比较明显的差异，典型正异常指数年，东亚夏季风比较强，而西太副高脊线偏北偏东，并且副高强度较弱；典型负异常指数年则刚好与之相反，夏季风较弱，西太副高脊线偏南偏西，且副高比较强。EAP遥相关型在500 hPa高度场中的异常分布特征对温度和大尺度环流形势有明显的影响，由此可进一步影响我国西南地区以及整个东亚的气候。

Abstract: In order to further study the influence of the teleconnection type on high temperature heat wave weather in southwestern China, this paper uses the daily maximum temperature data from 148 meteorological stations in southwestern China from June to August 1979-2019 and the monthly average potential height field of NCEP/NCER. According to the analysis data, the 500 hPa average geopotential height field from June to August is taken as the summer average height field. The natural orthogonal function (EOF) decomposition is used to obtain the spatial and temporal distribution characteristics of the high-temperature heat wave in the southwestern region, and then to the East Asia-Pacific (EAP) teleconnection. The 500 hPa geopotential height anomaly field of the typical posi-tive and negative anomaly index year is compared with the summer climatic average height field in 1979-2019. The results show that: 1) Overall, the number of high-temperature heat waves in the southwest region is much more in the east and the west is less, and Chongqing is a region with a large number of high-temperature heat waves. 2) The number of high-temperature heat waves in the southwestern region has an overall increasing trend. They have been increasing in recent years but have not changed much, but 2006 was a markedly increasing year of anomaly. Moreover, its spatial distribution has obvious east-west differences. It is a large-value area in eastern Sichuan and Chongqing, followed by Guizhou and most parts of Guangxi, and the number of high-temperature heat waves in Yunnan is low. 3) The interdecadal change of EAP teleconnection type is not obvious. It is mainly based on interannual changes. The large-scale circulation field in the typical positive and negative anomaly years of the EAP index has obvious differences. In the typical positive anomaly index year, the East Asian summer monsoon is strong, the position of the ridge of the Western Pacific Subtropical High is north-north-east, and the intensity of the sub-high is weak; the anomaly index year is just the opposite. The East Asian summer monsoon is weak, the ridgeline of the Western Pacific Subtropical High is more southerly and westerly, and the intensity of the subtropical high is stronger. The anomalous distribution characteristics of the EAP teleconnection type in the 500 hPa height field have a significant impact on the temperature and large-scale circulation situation, which can further affect the climate in southwestern China and the entire East Asia.