During landfall on the southeast coast of China, tropical cyclone (TC) Fung-Wong in the year 2008 caused torrential rainfall and flooding. In order to clarify the mechanism for the rainfall, a series of numerical simulations were conducted in this study using the National Center for Atmospheric Research (NCAR), Weather Research & Forecasting (WRF) mesoscale numerical model with three-nested domains and a highest horizontal resolution of 600 m. Numerical analysis was then performed based on the simulations. It is found that, during the evolution of heavy rainfall, quasi-frontal systems are frequently produced at the boundary of TC inflow and convective updrafts, which is more evident at the region of TC inner core and spiral rain band. The existence of energy cascading, featured by the energy transition among TC-scale inflow and convective cells, is also identified at the quasi-frontal region. These multiscale processes of Fung-Wong are further clarified by the analysis of helicity, which are believed to be responsible for the genesis and development of deep convection and rapid accumulation of rainfall. In the quasi-frontal region, numerical analysis further indicates the existence of intensive low-level wind shear as well as vertically turning of low level jet (LLJ), implying the contribution from Kelvin-Helmholtz instability (KHI).
Part of the book: Finite Element Method