The polar vortex is a persistent large-scale cyclonic circulation in the middle and upper troposphere and stratosphere of the Arctic. Its activities and changes control the short-time-scale cyclone activities in the pan-polar semi-permanent activity center and the subpolar regions. Changes in the intensity of the polar vortex are directly related to The Arctic atmosphere, ocean, sea ice and ecological environment affect the low-level atmospheric circulation and the subpolar and even mid-latitude weather. During China's second Arctic scientific expedition, it was the warm anticyclonic circulation in the middle and upper Arctic stratosphere that changed to the cold cyclonic circulation. Circulation transition and polar vortex establishment period. Some scholars have explored the effect of polar vortex changes on low-level circulation through research on the coupling mechanism of the stratosphere and troposphere. The impact of explosive stratospheric warming on polar vortex changes has long attracted people's attention. This article summarizes our research on Understand the polar vortex, and summarize the recent progress in research on the role of polar vortex changes in low-level circulation and the mechanism of its impact on climate. Since the Arctic vortex and the subtropical high pressure are the two main atmospheric circulation entities that affect my country's weather and climate change, they are closely related. This paper uses NCEP/NCAR reanalysis data, 74 atmospheric circulation factors provided by the National Climate Center and monthly precipitation data of 160 stations in China, and uses methods such as synthetic analysis, correlation analysis and SVD to discuss The relationship between the Arctic vortex in summer and the atmospheric circulation in the Northern Hemisphere and the subtropical high was analyzed, and the simultaneous effects of the Arctic vortex and the subtropical high on precipitation in North China in summer were analyzed.

The results show that: (1) The changes in the Arctic vortex are not only closely related to the high-latitude height field, but also closely related to the mid- and low-latitude circulation. When the polar vortex anomaly is larger and stronger, the geopotential height in the mid- and low-latitude areas is significantly lower.

, the area and intensity of the subtropical high in the northern hemisphere tend to be smaller, and the northern boundary tends to shift to the south. Among them, the intensity of the subtropical high changes the most.

(2) There is basically a significant negative correlation between the polar vortex factor and the subtropical high factor in each subregion, but there is a positive correlation with the northern boundary and ridge position of the western Pacific and South China Sea subtropical highs.

(3) The polar vortex index, subtropical high ridge line and northern boundary index are mainly positively correlated with precipitation in North China, while the area and intensity index of the subtropical high are basically negatively correlated with precipitation in North China.

When the polar vortex in Asia and Europe expands abnormally southward, the subtropical highs in North Africa, the Atlantic Ocean, and North America shrink significantly and weaken, and the subtropical highs in the western Pacific and South China Sea move significantly northward, precipitation in North China is likely to increase.

Keywords: Arctic vortex; subtropical high pressure; North China summer precipitation. Chart classification number: P466 Document identification code: A Received date: 2007-01-29; Revision date: 2008-05-28 Fund project: National Natural Science Foundation of China key

Fund (40633015); China Meteorological Administration New Technology Promotion Project (Impact of Explosive Warming in the Northern Hemisphere Stratosphere and Polar Vortex Activity on Tropospheric Blockage in East Asia) *** Co-funded by Corresponding Author: Zhang Hengde, male, Hanshan, Anhui, Ph.D., main

Engaged in atmospheric dynamics research.

E-mail: zhanghengde1977@163.com. 1 Introduction The Arctic vortex and the subtropical high (referred to as the subtropical high) are the two main atmospheric circulation entities that affect my country's weather and climate change [1-3].

However, the effects of the polar vortex and the subtropical high on weather and climate are not isolated, but cooperate and synergize with each other. The polar vortex mainly reflects the characteristics of mid- and high-latitude circulation, and the subtropical high largely reflects the changes in the atmospheric circulation at mid- and low-latitudes, and both

They are closely related, and some people have linked the two to analyze their relationship with atmospheric circulation and their impact on the climate environment.

Shi Neng et al. [4] pointed out that the increasing trend of both is a direct cause of the long-term trend changes and interdecadal changes in winter temperature in my country.

Wu Shangsen et al. [5] used the polar vortex and the subtropical high as two main factors to establish a model for predicting abnormally cold months in South China in winter.

Liu Chuanfeng et al.[6] believe that the Asian polar vortex and the western Pacific subtropical high are the main factors causing low temperature and cold damage in the south.

Shi Zhenling [7] believed that the strength of the polar vortex and the subtropical high is the main cause of floods or droughts in the Jianghuai region.

Liang Jianyin et al. [1] regarded the intensity changes of the polar vortex and the subtropical high as the main predictors of droughts and floods in Guangdong during the pre-flood season.

Sun Li et al. [8] analyzed the impact of the spring polar vortex and the western Pacific subtropical high on the East Asian atmospheric circulation in autumn.

Huang Jiayou et al. [9] found that a comprehensive study of the two impacts on summer precipitation in my country is better than studying their respective impacts separately, and the forecast value is also higher.

Peng Weigeng et al. [10] also found that changes in the two conditions in April had a significant impact on Ningxia sandstorms.

The above-mentioned studies all considered the changes of the polar vortex and the subtropical high in the process of diagnosing and analyzing the evolution of weather, climate and environment, and failed to discuss the interaction between the two. Therefore, it is necessary to explore the relationship between the polar vortex, atmospheric circulation and the subtropical high.

To better analyze their impact on weather and climate.

Precipitation in North China is mainly concentrated in summer, accounting for more than 3/4 of the total annual precipitation. In recent years, people have done a lot of research on summer precipitation in North China, and pointed out monsoon activities [11], blocking high pressure [12], and the western Pacific subtropical high

[13], the Arctic Oscillation [14], the South Asian High [15], thermal anomalies over the Tibetan Plateau [16] and even high-latitude circulation anomalies in the Southern Hemisphere [17] all have a certain impact on summer precipitation in North China.

These results provide some influencing mechanisms of summer precipitation in North China, and have certain indicative significance for the prediction of summer droughts and floods in North China. However, they fail to combine the polar vortex and the subtropical high to discuss their simultaneous effects on precipitation in North China.