A short-range ensemble prediction system for southern Africa

INTRODUCTION This research has been conducted in order to develop a short-range ensemble numerical weather prediction system over southern Africa using the ConformalCubic Atmospheric Model (CCAM). An ensemble prediction system (EPS) combines several individual weather model setups into an average forecast system where each member contributes to the final weather forecast (Atger, 1999). Four different EPSs were configured using lagged-average forecasting techniques (Kalnay, 2003) and two different cloud parameterisation schemes (McGregor, 2003; Rotstayn, 1997). Rainfall forecasts were simulated for seven days for the summer months of January and February, 2009 and 2010, for high (15 km) and low (50 km) resolution over the southern African domain. Statistical analyses were performed on the forecasts so as to determine which EPS was the most skilful at simulating rainfall. Measurements that were used to determine the skill of the EPSs were: reliability diagrams; relative operating characteristics; the Brier skill score; and the root mean square error. These scores will allow for a conclusion to be drawn as to which system performs the best, and what future research should be pursued.