@@ A Short-Range Ensemble Forecast system is under development by perturbing initial conditions and lateral boundary conditions based on a regional model, AREM (Advanced Regional Eta Model), which has 11 members in 37km horizontal resolution over China. Two strategies in perturbing IC were compared to examine an optimal approach in building a regional ensemble prediction system (EPS): one is directly applying perturbations from a global EPS to the regional EPS(a downscaling of a global EPS,Sch-l), and another is generating own perturbations by the regional model itself(BGM,Sch-2). The following four results can be seen.(l) By evaluating ensemble spread and probabilistic forecasts, it shows that the "Sch-2" seems to be superior to the "Sch_l" in this preliminary study (Fig.1).(2) No matter what IC perturbation strategies were applied,ensemble-based forecasts, ensemble mean and probabilistic forecasts, are in general outperform single control and operational forecast. (3) The ensemble spread and forecast skill are positively correlated quite well on domain average,the spatial correlation between spread and forecast error is about 40-45% on average.
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