5A.4
An Introduction to the Short-Range Forecast System for Typhoon Quantitative Precipitation Forecasts in Taiwan Area
PAPER WITHDRAWN
Shinn-Liang Shieh, Central Weather Bureau, Taipei, Taiwan; and G. J. Jian and J. A. McGinley
Taiwan is one of the regions around the world frequently affected by tropical cyclones with an average of 3.6 events annually. A major forecasting technique development of the Central Weather Bureau (CWB) in Taiwan has been to improve the quantitative precipitation forecasts (QPF) of typhoons. Abundant data, such as Doppler radars, satellite, soundings, and dense surface observations over Taiwan area provides an opportunity for diabatic data assimilation. Within the CWB, a real-time mesoscale forecast system using the fifth-generation Pennsylvania State University - National Center for Atmospheric Research Mesoscale Model (MM5) initialized diabatically with the modified Local Analysis and Prediction System (CWB-LAPS; Jian et al. 2003) was established for the short-range QPF of heavy rainfall events since the spring of 2003. The purposes of this paper are to present the performance of the CWB-LAPS diabatic data assimilation technique and investigate the impact of the Doppler radar data on the short-range precipitation forecasts for typhoons. Results from verified typhoon cases showed that the MM5 initialized diabatically with CWB-LAPS has higher skill for rainfall forecasts than the non-LAPS cold start experiment, especially for the higher thresholds in the early portion of model integration. Furthermore, the assimilation of Doppler radar data played a key role in the improvement of precipitation forecasts owing to the better presentation of typhoon hydrometeorological features in the model initial conditions.
Session 5A, Tropical cyclone Rainfall I
Tuesday, 4 May 2004, 8:00 AM-9:45 AM, Le Jardin Room
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