ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 50 Issue 11 > 2024,50(11):1306-1316. DOI:10.7519/j.issn.1000-0526.2024.101201 Prev Next
Analysis on Structure Changes of Landfall Northbound Typhoons and the Heavy Precipitation in Liaodong Peninsula Induced by Them
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Abstract:
The landfall tropical cyclones can often bring heavy precipitation to Liaodong Peninsula when they move northward into the Bohai Sea. Using CMA Tropical Cyclone Yearbook, cloud top brightness temperature and ERA-Interim reanalysis data, we conduct dynamic synthesis and diagnostic analysis of seven typhoons that caused heavy precipitation over the Liaodong Peninsula during their northward moving. The major conclusions are as follows. The typhoons experienced extratropical transition when approaching westerly troughs and had hybrid structures with remarkable baroclinic instability. Meanwhile, the vertical wind shear was enhanced, the vertical structure of the typhoon vortex slanted with height, and mesoscale convection developed on their north sides. The locations of heavy precipitation mainly occurred in the left side along with the direction of vertical wind shears. The standing link of typhoon with a deep southwestern or southeastern jet was favorable for the development of sustained convective activities in the typhoon rain belts, and the typhoons decayed slowly due to abundant moisture supply. Basically, strong-rainfall typhoons moved northward near the entrance area of the westerly jet stream in front of the trough, characterized by strong divergence in the upper layers. The coupling dynamical structure of positive divergence zone and the positive vorticity at lower levels formed, which was favorable for genesis of heavy precipitation and long-time substation of typhoon circulation. The cold air in the middle and upper troposphere invaded into typhoons’ northwest sides and the frontal zone slanted towards northwest with height, increasing the convective instability in the low-level front zone. The coupling dynamic structure of positive vorticity region and the divergence center further uplifted the air on their northeast sides and southeast sides. Liaodong Peninsula was in the north side of the typhoons, possessing strong low-level convergence, vertical wind shear, and deep and persistent vertical motion, thus the precipitation intensity was high and the duration was long over the Liaodong Peninsula.
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Clc Number:
P447,P445
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