What is the effect of subtropical high on climate?

The subtropical high affected by land and sea distribution is divided into several high-pressure units, which are called subtropical high. It is an important part of atmospheric circulation and an important large-scale weather system in subtropical areas. Subtropical high is a strong warm high, which exists all the year round and is stable and inactive.

The subtropical high in the western Pacific has an important influence on China's climate, especially the high ridge in the west. Its range is on a map of 500 hectopascals, represented by line 588, and its position and intensity change with the seasons. In the north-south direction, the change of its position is expressed by the average latitude of the subtropical ridge. From June to August, the average ridge line is located at 24 north latitude. In the east-west direction, its position is expressed by the longitude of the west extension end of the 588 line, with an average of east longitude 122. The intensity and location of the western Pacific subtropical high have obvious seasonal variations. Before June every year, the ridge line of subtropical high is located in the south of 20 north latitude, and there is a cross between warm air flow and cold air at the northern edge of high pressure. Frontal and cyclone activities are frequent, resulting in a wide range of rainy weather, so at this time of year, South China enters the rainy season; In the middle and late June, the ridge of subtropical high moved northward and stabilized at 20 ~ 25 north latitude, and the rain belt also moved northward, and the middle and lower reaches of the Yangtze River entered the rainy season, which is often called Meiyu. In early and middle July, the ridge line of subtropical high continued to move northward, swinging back and forth between 25 and 30 north latitude, and then the lower reaches of the Yellow River entered the rainy season. At this time, the plum rains in the middle and lower reaches of the Yangtze River ended and entered the midsummer. Due to the control of the high pressure ridge, there was a summer drought and the weather was very hot. From the end of July to the beginning of August, the ridge line of subtropical high jumps over 30 north latitude, reaching the northernmost point of the year, so the northern and northeastern parts of North China enter the rainy season. By the end of August or early September, the ridge of high pressure stopped moving northward and began to withdraw southward, and the rain belt also moved southward. 10 months later, the high-pressure ridge retreated to the south of 20 north latitude, and the rainy season ended in most parts of China. From the above-mentioned influence of the western Pacific on the weather and climate in China, it is not difficult to see the seasonal activity characteristics of the western Pacific subtropical high. That is, when moving northward in summer, the moving speed is slow and the duration is long. In autumn, when it moves south, it is very fast and lasts for a short time. This is enough to show that its inter-annual activities have changed a lot. Once these activities are abnormal, it will lead to large-scale droughts and floods in China.