Abstract:
This research has been conducted in order to develop a short-range ensemble numerical
weather prediction system over southern Africa using the Conformal-Cubic 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. Four different EPSs were configured and rainfall forecasts
simulated for seven days ahead 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 analysis was 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. The results show that the largest ensemble
is consistently the most skilful for all forecasts for both the high and the low resolution
cases. The higher resolution forecasts were also seen to be more skilful than the forecasts
made at the low resolution. These findings conclude that the largest ensemble at high
resolution is the best system to predict rainfall over southern Africa using the CCAM.
