Analysis Of Wind Speed Characteristics Of Tropical Cyclones Based On Dropsond

In this paper,the vertical and horizontal wind speed distribution characteristics of tropical cyclones over the western Atlantic and Northeast Pacific are studied based on the dropsonde dataset and the best path dataset.In this paper,the normalized radius is used to describe the relative position of the dropsondes containing wind speed and other data in a tropical cyclone,namely R/RMW(where R is the distance between the dropsondes and the center of the tropical cyclone,and RMW is the maximum wind speed radius of the tropical cyclone).In this paper,the area where the normalized radius of tropical cyclone R/RMW<5 is called the tropical cyclone near-region,the area with 5≤R/RMW<10 is called the far-region,and the area with R/RMW≥10 is the outer-region.In the lower atmosphere,there is no obvious difference between the vertical wind low wind speed in the near,far and outer regions of tropical cyclones.However,the high wind speed segment has the highest positive frequency in the near-region than in the far-region and the outer-region,while the negative frequency in the outer-region is the highest than in the nearregion and the far-region.The frequency of updrafts in the near-region decreases with the increase of altitude,while the frequency of downdrafts increases.The change of updrafts in the far and outer-region is not obvious with the increase of altitude.The distribution proportion of strong updraft in all azimuths of tropical cyclones is less than 10%,especially in the north and northeast.The velocity and proportion of strong updrafts in the near-region increased with the increase of tropical cyclone intensity,while the median vertical wind speed in the far and outerregion did not change significantly with the intensity.Strong updrafts are less common in rapidly intensifying,low-intensity tropical cyclones,and are more closely related to the intensity itself.The strong horizontal wind is mainly distributed in the atmospheric boundary layer in the near-region,while the low wind speed section in the far and outer-region are usually near the surface of the horizontal wind.Along the tropical cyclone center,the distribution of strong horizontal winds changes from northeast to northwest counterclockwise.The influence of moving speed on strong updraft is small.In the normalized radius 1-2 region,the fast moving speed will suppress the strong horizontal wind,and the effect is less in other regions.The extreme updraft of tropical cyclone can exceed 10 m/s,and the intensity of tropical cyclone needs to reach 50 m/s,They are mainly distributed in the north and northeast of the 1≤R/RMW<2.5 region.The extreme horizontal wind(≥90 m/s)usually occurs in the south of the1≤R/RMW<2.5 region,and the tropical cyclone intensity reaches more than 70 m/s.