Impact of Kalpana-1-Derived Water Vapor Winds on Indian Ocean Tropical Cyclone Forecasts

Abstract

The water vapor winds from the operational geostationary Indian National Satellite (INSAT) Kalpana-1 have recently become operational at the Space Applications Centre (SAC). A series of experimental forecasts are attempted here to evaluate the impact of water vapor winds derived from Kalpana-1 for the track and intensity prediction of two Bay of Bengal tropical cyclones (TCs), Sidr and Nargis, using the Weather Research and Forecasting (WRF) modeling system. The assimilation of water vapor winds has made some impact in the initial position errors as well as track forecasts when compared with the corresponding control experiments for both TCs. However, no statistically significant improvement is noticed in the simulations of TC intensities [i.e., minimum sea level pressure (MSLP) and maximum surface winds forecasts when satellite winds are used for assimilation]. Moreover, the performance of Kalpana-1 winds is evaluated by repeating the same sets of experiments using Meteosat-7 winds derived at the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and compared with observed data. The simulation of initial position errors, and track and intensity forecasts using the assimilation of water vapor winds from both satellites are comparable. Though, these results are preliminary with respect to the Kalpana-1 winds, the present study can provide some insight to the WRF model users over the Indian Ocean region.