Extended Prediction of North Indian Ocean Tropical Cyclones Using the ECMWF Variable Ensemble Prediction System - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 111

Extended Prediction of North Indian
Ocean Tropical Cyclones Using the
ECMWF Variable Ensemble
Prediction System
Peter J. Webster*, James I. Belanger and Judith A. Curry
School of Earth & Atmospheric Sciences, Georgia Institute of Technology
Climate Forecasts Applications Network (CFAN)
Atlanta GA, US
*email: [e-mail]
1. Introduction
This analysis examines the predictability of several key forecasting parameters
using the ECMWF Variable Ensemble Prediction System (VarEPS) for tropical
cyclones (TCs) in the North Indian Ocean (NIO) including: tropical cyclone
genesis, pre-genesis and post-genesis track and intensity projections and regional
outlooks of tropical cyclone activity for the Arabian Sea and the Bay of Bengal.
Based on the evaluation period from 2007 to 2010, the VarEPS TC genesis
forecasts demonstrate low false alarm rates and moderate to high probabilities
of detection for lead-times of one to seven days. In addition, VarEPS pre-
genesis track forecasts on average perform better than VarEPS post-genesis
forecasts through 120 hrs and feature a total track error growth of 41 nm per
day. The VarEPS provides superior post-genesis track forecasts for lead-times
greater than 12 hrs compared to other models including: UKMET, NOGAPS
and GFS, and slightly lower track errors than the Joint Typhoon Warning Center.
For a more complete description, please see Belanger et al. (2012).
2. Data and Methods
2.1 Model Forecasts
As of 26 January 2010, the VarEPS includes the ECMWF global model that is
run at TL1279 spectral truncation (horizontal resolution ~16 km) with 91 vertical