21.3 The NOAA/NWS/NCEP Short Range Ensemble Forecast (SREF) system: Evaluation of an initial condition vs multiple model physics ensemble approach

Abstract

The NCEP multi-Initial Condition (multi-IC) and multi-model Short Range Ensemble Forecasting (SREF) system has been operationally running since May 2001 (Du et al. 2003). Recent studies have shown the benefits of adding physics perturbation members to an ensemble system (Stensrud et al. 2000). Also, ensemble members clustering by model is a main concern of field forecasters. Therefore, a new physics ensemble system has been developed and is now under testing and evaluation. This paper summarizes the NCEP SREF system and reports on some of our findings from a comparison study between a multi-IC and multi-physics ensemble approach for short range forecasts (1-3 days).