The Taiwan WRF Ensemble Prediction System: Scientific description, model-error representation and performance results

The most skillful ensemble is obtained if model-uncertainty is represented in addition to initial condition uncertainty. A number of numerical prediction experiments are conducted to obtain the optimal configuration consisting of multiple physics-schemes, and two stochastic parameterization schemes: The Stochastic-Kinetic Energy Backscatter (SKEB) Scheme and the Stochastically Perturbed of Physics-Tendency (SPPT) scheme.

The performance of the best configuration of WEPS is objectively verified against ECMWF reanalysis and a high-resolution simulation. Further analysis finds little impact of the stochastic schemes on quantitative precipitation forecasts and a single Typhoon case study. We conclude that for best performance over the East Asian domain, stochastic parameterizations alone are not sufficient to represent model-uncertainty and need to be augmented with a multi- physics suite.