IMPACT OF MODEL RESOLUTION AND ENSEMBLE SIZE ON THE PERFORMANCE OF ANENSEMBLE PREDICTION SYSTEM

Ensemble integrations for 14 cases are described. These integrations t est the relative impact of increase in ensemble size and in the resolu tion of the model used to integrate the ensemble. The ensembles are ev aluated using a variety of statistical tests. Some of these indicate a relative advantage of an increase in ensemble size, whilst most tests suggest a relative advantage of an increase in model resolution. Howe ver, overall, the best performance was obtained by combining enhanceme nt in model resolution (from T63L19 to T106L31) with an increase in en semble size (from 32 to 50 members).