青藏高原, 大气热源, 高温日数, 川渝盆地

It is of great significance to study the relationship between summer atmospheric heat source over the Qinghai-Xizang Pla⁃

teau and its surrounding area and the number of high temperature days in the Sichuan-Chongqing Basin for summer high temperature prediction and high temperature and drought disaster prevention. Based on the daily maximum temperature data of 125 meteorological stations in the Sichuan Chongqing Basin and monthly NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) reanalysis dataset, the characteristics of summer high temperature days in the Sichuan-Chongqing Basin and relationship between the inter-annual variation of high temperature days there and atmospheric heat source over the Qinghai-Xizang Plateau and its surrounding area are discussed. The results show that the first mode of EOF decomposition of high temperature days presented a consistent type in the whole region, which can reflect the main distribution characteristic of summer high temperature days. The summer high temperature days in the basin significantly increased from 1979 to 2022, showing obvious inter-annual and interdecadal variation characteristics. There is a close relationship between the atmospheric heat source over the eastern part and its eastern side of Qinghai-Xizang Plateau and the inter-annual variation of summer high temperature days in the basin. When the heat source over the key region of the plateau is relatively weak (strong), the corresponding high temperature days in the basin are significantly more (less). On the inter-annual scale, when the atmospheric heat source over the eastern part and its eastern side of Qinghai-Xizang Plateau is weaker than normal, the position of South Asian high shifts northeastward, and the western Pacific subtropical high shifts northwestward, The water vapor transport from the South China Sea, western Pacific, and Bay of Bengal to the basin is significantly weakened, combined with significant subsidence anomalies over the basin, resulting in less precipitation and high temperature days there. At the same time, the total cloud cover in the basin is less than normal, and the short-wave solar radiation flux reaching the ground increases significantly, resulting in a rise in ground temperature and an increase in the number of high-temperature days. When the atmospheric

heat source over the eastern part of the plateau and its eastern side is relatively strong, the circulation pattern is beneficial for reducing the number of high temperature days in the basin.

Qinghai-Xizang Plateau, atmospheric heat source, high temperature days, Sichuan-Chongqing Basin