Ensemble rainfall forecasting with numerical weather prediction and radar-based nowcasting models

摘要

The overall objective of this study is to improve the forecasting accuracy of the precipitation in the Singapore region by means ofnboth rainfall forecasting and nowcasting. Numerical Weather Predication (NWP) and radar-based rainfall nowcasting are twonimportant sources for quantitative precipitation forecast. In this paper, an attempt to combine rainfall prediction from a highresolutionnmesoscale weather model and a radar-based rainfall model was performed. Two rainfall forecasting methods werenselected and examined: (i) the weather research and forecasting model (WRF); and (ii) a translation model (TM). The WRFnmodel, at a high spatial resolution, was run over the domain of interest using the Global Forecast System data as initializingnfields. Some heavy rainfall events were selected from data record and used to test the forecast capability of WRF and TM.nResults obtained from TM and WRF were then combined together to form an ensemble rainfall forecasting model, by assigningnweights of 0.7 and 0.3 weights to TM and WRF, respectively. This paper presented results from WRF and TM, and the resultingnensemble rainfall forecasting; comparisons with station data were conducted as well. It was shown that results from WRF arenvery useful as advisory of anticipated heavy rainfall events, whereas those from TM, which used information of rain cells alreadynappearing on the radar screen, were more accurate for rainfall nowcasting as expected. The ensemble rainfall forecastingncompares reasonably well with the station observation data. Copyright © 2012 John Wiley & Sons, Ltd.