副热带高压（以下简称副高）是副热带高压带受海陆分布的影响所断裂形成的单体，是制约大气环流变化的重要成员之一，对热带、副热带及邻近地区的气候变化有重要的影响。本文利用NCEP-DOE Reanalysis 2和ERA5等再分析数据，通过多种统计方法对全球副高系统的时空分布特征进行诊断分析，还探究了副高对关键区夏季高温事件的影响。结果表明：

北太平洋副高（NPSH）、北大西洋副高（NASH）、南大西洋副高（SASH）和南印度洋副高（SISH）强度均有增加趋势。全球副高的强度变化随中心纬度变化显著，北半球副高（NPSH、NASH）强度随中心北移而增强，而南半球副高（SASH、SISH）强度随中心南移而增强。NPSH的位置受北大西洋海温的调控（NA指数，相关系数：-0.38，通过95%信度检验），当北大西洋海温偏低时，热带和中高纬太平洋海温偏高，增强了30°N-40°N区域内的下沉运动，使得NPSH位置偏北、强度加强。NASH和SASH的位置受中东太平洋海温的影响（Ni?o-3.4指数，相关系数：-0.48，-0.40，均通过95%信度检验），当中东太平洋海温偏高，赤道大西洋海温偏低时，NASH强度减弱，SASH强度增强。最后，SISH的位置受AAO的制约（相关系数：-0.32，通过95%信度检验），当南印度洋海温偏高时，使得SISH位置南移且增强。因此，全球副高的强度及位置关系具有显著的年际变化特征，并且均受气候系统内部变率的影响。

相较于850 hPa高度场，500 hPa高度场与关键区夏季气温相关性更高。东亚地区夏季高温事件分别与NPSH（相关系数：0.54，通过99%信度检验）和NASH（相关系数：0.51，通过99%信度检验）相关性较好，北美地区夏季高温事件分别与NPSH（相关系数：0.41，通过99%信度检验），NASH（相关系数：0.30，通过90%信度检验）和SASH（相关系数：0.26，通过90%信度检验）相关性高，而欧洲地区主要受NASH（相关系数：0.34，通过95%信度检验）和SASH（相关系数：0.30，通过90%信度检验）的影响。研究发现在高温年夏季，500 hPa副高面积相较气候态偏大，NPSH与NASH连通，关键区被异常反气旋控制。其中东亚地区夏季高温年时，东太平洋海温从冬季开始降低，直到夏季出现冷舌。低层西太平洋的罗斯贝波响应使得东亚地区在夏季被异常反气旋控制。北美地区高温年时，东太平洋海温全年持续偏暖，激发的开尔文波向东传播，使得北美地区被异常反气旋控制。欧洲地区高温年时，夏季SASH出现在南美洲上空。中东太平洋海温由冬季开始逐渐下降，东太平洋冷舌从夏季开始出现，偏低的东太平洋海温会在其东侧激发异常的气旋性环流，使得大西洋海温升高，在欧洲上空激发出异常的反气旋环流。高空的罗斯贝波列沿环球遥相关路径影响关键区的夏季气温。因此，三个关键区的高温夏季事件分别对应不同的太平洋海温的变化，并且均受环球遥相关波列的影响。

The subtropical high is a single unit formed by the subtropical high belt that is broken by the influence of the distribution of sea and land. It is one of the important members that restrict the changes of atmospheric circulation and has an important impact on climate change in the tropics, subtropics, and adjacent areas. This paper uses NCEP-DOE Reanalysis 2 and ERA5 to analyze the temporal and spatial distribution characteristics of the global subtropical high system through a variety of statistical methods and explores the impact of subtropical high on hot summer events in key areas. The results show:

The intensity of the North Pacific Subtropical High (NPSH), North Atlantic Subtropical High (NASH), South Atlantic Subtropical High (SASH) and South Indian Ocean Subtropical High (SISH) all have increasing trends. In addition, the intensity of the global subtropical highs vary significantly with the central latitude. The intensities of the northern hemisphere subtropical highs (NPSH, NASH) increase as the centers move northward, and the intensities of the southern hemisphere subtropical highs (SASH, SISH) increase as the centers move southward. The location variability of NPSH is regulated by the North Atlantic sea surface temperature (sst, NA index, correlation coefficient: -0.38). When the North Atlantic sst is low, the tropical and mid-high latitude Pacific sst is higher, which increases the sinking movement of 30°N-40°N and makes the NPSH position more norther and stronger. The variability of NASH and SASH will be affected by the sst of the Central and Eastern Pacific (Ni?o-3.4 index, correlation coefficient: -0.48, -0.40). When the sst of the Central and Eastern Pacific is high, the sst of the equatorial Atlantic is low, the intensity of NASH decreases and SASH increases. Finally, the variability of SISH is restricted by AAO (correlation coefficient: -0.32). When sst in the South Indian Ocean is high, the position of SISH moves southward and strengthens. Therefore, the intensity and location of the global subtropical highs have significant interannual variability, and are all affected by the internal climate variability.

Compared with the 850 hPa, the summer temperature in key areas have a higher correlation with the 500 hPa geopotential height. Hot summer events in East Asia have relatively good correlations with NPSH (correlation coefficient: 0.54) and NASH (correlation coefficient: 0.51), respectively. Hot summer events in North America are related to NPSH (correlation coefficient: 0.41), NASH (correlation coefficient: 0.30) and SASH (correlation coefficient: 0.26), while the European hot summer events mainly affected by NASH (correlation coefficient: 0.34) and SASH (correlation coefficient: 0.30). The study found that during hot summer years, the area of the 500 hPa subtropical highs is larger than climatology, NPSH is connected to NASH, and key areas are controlled by anomalous anticyclones. In East Asia, the sst in the East Pacific decreases from winter to the cold tongue in summer. The Rossby wave response in the lower western Pacific makes East Asia controlled by anomalous anticyclones in summer. During the hot summer years in North America, the sst in the East Pacific continued to be warm throughout the year, and the Kelvin wave triggered to propagate eastward, causing North America to be controlled by an abnormal anticyclone. In hot summer years in Europe, SASH appears over South America in summer. The sst of the Central and Eastern Pacific gradually decreases from winter, and the cold tongue appears in the eastern Pacific from summer. The lower sst of the Eastern Pacific will trigger anomalous cyclonic circulation on its east side, which will increase the sst of the Atlantic Ocean and stimulate anomalous anticyclonic circulation to Europe. The Rossby wave affects the summer temperature in key areas along the global teleconnection path. Therefore, hot summer events in three key areas correspond to different patterns of Pacific sst and they are affected by global teleconnection path.