Skill of a superensemble forecast over equatorial Southeast Asia

Abstract

AbstractThe performance of the multianalysis–multimodel superensemble weather forecast and its comparison with several other operational prediction models is investigated in this study for the Southeast Asian region. The superensemble technique has been proven to exhibit exceptional skills compared with individual or even ensemble average forecasts for parameters such as precipitation, motion and mass fields. Precipitation forecasts from the superensemble technique for the year of 2001 from this study show that its skill scores are better than the other global operational models employed. Its precipitation root‐mean‐square errors (RMSEs) are consistently lower than the other member models for the annual period examined. The equitable threat score, which indicates the association of the common rainfall threshold distribution between the forecast and observed best rainfall analysis from the Tropical Rainfall Measurement Mission and Special Sensor Microwave Imager dataset, is slightly underpredicted for light rain thresholds, but it still outperforms the other individual members or even the ensemble mean forecasts. Correlation analysis of the superensemble forecast against the observed is far higher than either the ensemble mean or the individual forecast member models and is maintained for up to 3‐day forecasts.The motion field comparisons also exhibit that the superensemble forecasts are closer to the observed data than the other member models due to its low systematic errors at the 850 hPa pressure level. Both the precipitation and wind field analyses have shown that the Florida State University multianalysis–multimodel superensemble forecast provides the lowest RMSE, the highest correlation against the best‐observed data and lowest systematic errors compared with the other participating operational models. These forecasts have the potential to provide better daily weather predictions over the Southeast Asian region, particularly during the early northeast monsoon that often causes heavy rainfall in the equatorial part of the Southeast Asian region. Copyright © 2004 Royal Meteorological Society