Meso-gamma structure and dynamics of meso-cyclones associated with TC Gabrielle (2001) using high-resolution data of east-central Florida and MM5 integrations.

摘要

Nowcasting of Tropical Cyclone (TC) outer rainband tornadoes poses a difficult problem even with the advent of WSR-88D in the National Weather Service. This is due to the subtle signatures of TC tornadoes and the shallowness of the convection. Numerical modeling of these phenomena is even more difficult due to the limited availability of data at finer scales. A routine mesoscale model with a low-resolution data set (1° x 1°) cannot represent these meso-gamma (2-km to 20-km) scale features in model simulations. To simulate these events data over a fine scale is needed for initialization.; In an attempt to simulate the features of TC Gabrielle (2001) outer rainband tornadoes, the MM5 model is used with four domains (54-km, 18-km, 6-km and 2-km) with the finest domain resolution over meso-gamma scales. Two different simulations were done separately to check the sensitivity of the initialized data, one with the routine final analysis (FNL) data and the other with high-resolution (4-km x 4-km) data in the fine domains along with FNL data in the coarse mesh. Further sensitivity of different parameterization schemes for cumulus convection and the boundary layer are also tested for TC movement and intensity.; Various parameters such as baroclinicity, streamlines, vertical velocity, and vorticity are studied for the tornadic-mesocyclone environment. Further, parameters such as storm-relative helicity and the tilting term for the vorticity budget are computed and analyzed for the TC tornado environment.