Impact of Radiance Data Assimilation on Simulation of Tropical Cyclone Thane Using WRF-3DVAR Modelling System - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 378

Impact of Radiance Data Assimilation
on Simulation of Tropical Cyclone
Thane Using WRF-3DVAR
Modelling System
A. Routray*, U.C. Mohanty 1 and Krishna K. Osuri 1
National Centre for Medium Range Weather
Forecasting, Sector 62, Noida, India
1 Centre for Atmospheric Sciences
Indian Institute of Technology Delhi, New Delhi, India
*e-mail: [e-mail]
1. Introduction
Tropical cyclones (TCs) are well known for their devastation, mainly due to
torrential rains, strong winds and associated storm surges, which cause flooding,
soil erosion and landslides, even far away from the landfall location, resulting
in numerous human casualties and enormous property damage. These disasters
are particularly severe over the North Indian Ocean (NIO), comprising both
the Bay of Bengal (BoB) and Arabian Sea (AS), as their coastal areas are
heavily populated. In the past 300 years, out of all recorded cases of very
heavy loss of life (ranging from about 5000 to well over 300,000) in the world
due to TCs, more than 75% cases have occurred in the BoB and AS (WMO
Technical Report, 2008).
The performances of numerical weather prediction (NWP) models are not
satisfactory in prediction of the intensity and track of TCs over the NIO
(Mohanty and Gupta, 1997; Gupta, 2006) and need improvements in the 48-
and 72-hour forecast time scales. This may be mainly due to the lack of sufficient
conventional observational data over the oceans where TCs form and evolve.
Hence, the global analyses which serve as initial and boundary conditions (IBCs)
to mesoscale models are ill-defined in representing the initial structure and
position of the vortex. According to Mohanty et al. (2010), the initial vortex
position error in global analyses is about 100 km and further contributes to
more track forecast errors. The primary and important task is to reduce the