Impact of Microphysics Schemes in the Simulation of Cyclone Phailin using WRF model

摘要

A Very Severe Cyclonic Storm (VSCS) "Phailin" crossed Odisha coast near Gopalpur on 12 October, 2013 and caused significant damage to property due to both wind and surge. High surge (~2.3m). generated by the cyclone washed away some of the coastal structures (groins and break waters) constructed at the Gopalpur port besides causing coastal erosion. Wind damage was quite extensive around 50km radius of the cyclone track. In the present study, an attempt is made to simulate and test the capability of the state of art Weather Research and Forecasting meso-scale model (WRFV3) in capturing the wind intensity and track of cyclone accurately. The simulation has been carried out using two domains with a horizontal resolution of 27 km for domain 1 and 9 km for domain2. Multiple simulations using initial conditions (NCEP FNL) at an interval of 6 hours, same cumulus parameterization and time integration schemes but with different microphysics schemes are carried out. The objective of the present study is to find the best microphysics for accurate simulation of intensity and track of tropical cyclone. Because, the main source of energy for tropical cyclone is the latent heat release (convective heating) in clouds, which depend on microphysical processes and the related cloud dynamical properties. The model was integrated for 108 hours starting from 9 October, 2013 to 13 October, 2013. Simulated features include track, intensity, rainfall and other synoptic conditions. As a test of the model performance, some observed features (track, maximum sustained wind, and sea level pressure) were compared with simulations and it was observed that simulations with WRF Single Moment-3 (WSM3) class microphysics scheme compare well with observations. Other synoptic features like, low level divergence, vorticity, and simulated rainfall are also discussed in relation to model performance. Impacts of Phailin on coastal structures are also discussed.