Variation of Dynamical Parameters with Upper Tropospheric Potential Vorticity in Tropical Cyclone over the North Indian Ocean Using WRF Model

Abstract

Meteorologists are experiencing many challenges in the reliable forecasting of the track and intensity of tropical cyclones (TC). Uses of the potential vorticity (PV) technique will enrich the current forecasting system. The use of PV analysis of TC intensification over the North Indian Ocean (NIO) is rare. In this study, the authors analyze the behaviour of upper-level PV with dynamic parameters of TCs over NIO. The authors used NCEP FNL reanalysis 1 × 1 degree data as input in WRF model version 4.0.3 with one-way nesting between the parent and child domains. The authors used a coupling of the Kain-Fritsch (new Eta) scheme and the WSM 6-class graupel scheme as cumulus and microphysics options to run the model. The authors found that at least 1 potential vorticity unit (PVU) (1 PVU = 10–6 m2 s –1KKg–1) upper PV is required to maintain the intensification of TC Titli. Larger upper PV accelerates the fall of central pressure. The high value of upper PV yields the intensification of TC. The wind shear and upper PV exhibited almost identical temporal evolution. Upper PV cannot intensify the TCs at negative wind shear and shear above the threshold value of 12 ms–1. The upper PV and geopotential heights of 500 hPa change mutually in opposite trends. The upper PV calculated by the model is comparable to that of ECMWF results. Therefore the findings of this study are admissible.