Momentum Diagnostic Cause Analysis of Offshore North-ward Tropical Cyclone Gales in Shanghai Coastal Areas
GUAN Liang
YUE Caijun
CHEN Xi
YAO Yao
ZENG Zhihua
DENG Liping
Abstract：Based on the ERA5 reanalysis data and China Meteorological Administration(CMA)tropical cyclone best track data from 1981 to 2022,this study analyzes the gale characteristics induced by offshore and northward-moving tropical cyclones(TCs)in Shanghai coastal areas.A quantitative momentum budget diagnostic equation is then utilized to investigate their dynamic mechanisms.The results show that:(1)Substantial discrepancy exists in the maximum impact wind intensities among different TCs,and the intensities are strongly affected by the distance of the TCs from Shanghai coastal waters.(2)The pressure gradient acceleration(PGA)and the vertical advection(VA)terms are the primary dynamical mechanisms for TC gales in Shanghai coastal areas.The PGA term accounts for the major contribution,followed by the VA term,with the intensity of both terms strengthen with wind intensities.(3)Enhanced pressure gradient directly strengthens the PGA term,while the downward transport of high momentum from the boundary layer jet amplifies the VA term above the boundary layer,ultimately driving the TC gales in the Shanghai coastal areas.These results establish important guidance for TC gale forecasting and have practical value for operational applications,thereby offering a scientific basis for disaster prevention and mitigation.
Keywords：momentum budget diagnosisnorthward offshoretropical cyclone galesdynamic analysis
Publication Date：2025-08-30
Online Publishing Date：2025-09-23(First online date of this platform, not the publication date of the document)
Pages：10( 531-540 )