Urgent! ! ! ! ! ! Brief answer to the flow field structure and weather characteristics of typhoon? Thank you very much.

The typhoon is warm and low pressure, so the ground flow field within the typhoon range is a cyclone convergence field. According to the convergent airflow speed, the lower layer of a mature typhoon can be divided into three areas along the longitude: (1) outer ring: from the edge of the typhoon to the outer edge of the maximum wind speed zone, the wind speed increases sharply towards the center, with the wind force above 6 and the radius of about 200-300 kilometers; (2) The middle circle: from the outer edge of the maximum wind speed area to the eye wall of the typhoon, it is the area with the strongest convection and wind and rain in the typhoon, with a radius of100 km; (3) Inner ring: the eye area of the typhoon, where the wind speed drops rapidly and the radius is about 5-30 kilometers.

The vertical distribution of typhoon airflow field can be roughly divided into three layers: (1) from the ground to 3 kilometers (mainly from the friction layer of 500- 1000 meters) is the low-level airflow inflow layer, and the airflow has a significant radial component converging toward the center. Due to the geostrophic bias, the inward airflow rotates in the cyclone. The closer it is to the typhoon center, the shorter the rotation radius, the greater the curvature of the isobar and the corresponding increase in centrifugal force. Under the action of geostrophic bias and centrifugal force, the inward airflow can't reach the center of the typhoon, and it strongly hovers around the eye wall of the typhoon. This layer has a decisive influence on the occurrence, development and extinction of typhoons; (2) The middle transition layer is about 3-8 kilometers, and the meridional component of the airflow is already very small, mainly circling around the eye wall of the typhoon in the tangential direction, and the rising speed reaches the maximum between 700-300 mbar; (3) From about 8km to the tropopause (about 12- 16km), it is the upper outer layer. This layer of updraft has a great tangential wind speed, and at the same time, it releases a lot of latent heat during the ascending process, which causes the temperature in the middle of the typhoon to be higher than that around it, and the horizontal pressure gradient force in the typhoon gradually decreases with the increase of height. When the updraft reaches a certain height (about 10-), the air outflow is roughly equivalent to the inflow of the inflow layer.

Weather:

Most typhoons are generated in convective clouds, so there are large clouds near the primary typhoon. With the continuous development of typhoon, a unique dense cloud area has been formed near the typhoon eye area. According to the satellite cloud image and radar echo of typhoon, the mature typhoon cloud system includes: (1) outer spiral cloud belt, which is composed of stratocumulus or cumulus clouds and spirals into typhoon at a small angle; (2) Inner spiral cloud belt: generally, a cloud belt consisting of several cumulonimbus clouds or cumulonimbus clouds is directly involved in the typhoon; (3) Cloud wall: it is a concentric cloud belt around the center of the typhoon, which is composed of towering cumulonimbus clouds, and the height of the cloud top can reach more than 12km. Like a towering cloud wall; (4) Typhoon eye area: Due to the sinking of airflow, the sky is clear and cloudless. If there is plenty of water vapor in the lower layer, some stratocumulus and cumulus clouds may be generated below the inversion layer, but the vertical development is not strong, there are many cloud gaps, and the typhoon area is full of water vapor and the airflow rises strongly, which often causes a lot of precipitation (200-300 mm, or even more). The precipitation is sudden, mainly in the vertical cloud wall area and the inner spiral cloud belt area, and there is generally no precipitation in the eye area.