关键词: 登陆热带气旋, 黄淮中部, 降雨非对称, 暴雨增幅, 弱冷空气, 风垂直切变

Abstract:

Based on optimal track data of tropical cyclone from China Meteorological Administration-Shanghai Typhoon Institute (CMA-STI), conventional observational data from Meteorological Information Combine Analysis and Process System (MICAPS), National Centers for Environmental Prediction (NCEP) 1°×1° reanalysis data, and temperature of black body (TBB) data retrieved from the FY-2G satellite, we analyzed the causes of rainstorms occurring in the central part of Huanghuai area from 02:00 on August 17 to 14:00 on August 19, 2018, influenced by a landing tropical cyclone (TC) "Rumbia".The results showed that short-time heavy precipitation occurs at most meteorological stations, which can be triggered by the front or rear borders of convective clouds, the train effect of convective cells, the central area of deep convective clouds, and the emergence of convective cells, as well as non-convective clouds.On August 17, rainstorms occur in the central and southern Huanghuai areas, at the right side of the pathway of "Rumbia".A middle-level inverted trough is located westward to a low-level inverted trough, which is favorable for the rainstorm formation in the central Huanghuai area.On August 18, several meso-scale systems are influencing the rainstorm, including the middle northern side of "Rumbia", a low-level inverted trough, the easterly jets, the TC circulation, and weak cold air.The enhanced precipitation in the central Huanghuai area is resulted primarily from the increase in convergence of water vapor at 925 hPa and divergence of water vapor at 400 hPa, and the increase of middle- and low-level equivalent potential temperature.The increase of vertical wind shear is a good indicator of strong precipitation.After 20:00 on August 18, upper-level southwesterly jets begin to form, and southerly winds along the east of low-level inverted trough enhance and move northward.With the coupling of upper- and low-level circulation, rainstorm in northern Shandong province develops, and rainstorm in the central Huanghuai area becomes weak obviously.

Key words: Landing tropical cyclone, Central Huanghuai area, Asymmetric precipitation, Rainstorm enhancement, Weak cold air, Vertical wind shear