Simulation of Bay of Bengal Cyclones using Mesoscale Models

U. C. Mohanty
Centre for Atmospheric Sciences IIT

The Bay of Bengal tropical cyclone disaster is the costliest and deadliest natural hazard in Indian sub-continent. It has significant socio-economic impact on the countries bordering the Bay of Bengal, in particular, India, Bangladesh and Mayanmar. Timely and reasonably accurate prediction of track and intensity of these storms can save loss of lives and reduce damage to properties.

The genesis and movement of the Bay of Bengal tropical cyclones are unique in nature compare to other region of cyclones. The high resolution mesoscale model MM5 is extensively tested over the basin with different parameterization schemes and different model horizontal resolution. The optimal configuration of the model with improved initial condition through vortex initialization and assimilation of satellite data is used to simulate all severe cyclonic storms (eight) over the Bay of Bengal during the period 1995-1999. The simulation results of these storms are illustrated with performance/forecast skill of the model. The intensity of the storms both in terms of central sea level pressure and strength of maximum wind is simulated with reasonable accuracy. The model simulated track of the storms followed the observed track closely and track forecast errors indicate reasonably good accuracy of the model.

Recently developed Hurricane Weather Research and Forecast (HWRF) model by NCEP is adopted over the Bay of Bengal region. The HWRF model is tested with the recently occurred tropical cyclone MALA in the Bay of Bengal. The model simulated track and intensity of the storm are compared with operational model forecasts of IMD and UKMO. The performance of the forecast skill of the HWRF model is appreciably better in this case. However, the model will extensively test in all eight sever cyclonic storms over the Bay of Bengal during the period 1995-1999 to evaluate performance of the model.