Verification and comparison of probabilistic precipitation forecasts using the TIGGE data in the upriver of Huaihe Basin

摘要

The precipitation forecasts of three ensemble prediction systems (EPS) andtwo multi-model ensemble prediction systems (MM EPS) were assessed bycomparing with observations from 19 rain gauge stations located in theDapoling-Wangjiaba sub-catchment of Huaihe Basin for the period from 1 July to 6August 2008. The sample Probabilistic Distribution Functions (PDF) of gammadistribution, the Relative Operating Characteristic (ROC) diagrams, thepercentile precipitation and a heavy rainfall event are analyzed to evaluatethe performances of the single and multi-model ensemble prediction system(EPS).The three EPS were from the China Meteorological Administration (CMA); theUnited States National Centre for Environment Predictions (NCEP); and theEuropean Centre for Medium-Range Weather Forecasts (ECMWF), all wereobtained from the TIGGE-CMA archiving centre (THORPEX Interactive GrandGlobal Ensemble, TIGGE). The MM EPS were created using the equal weightingmethod for every ensemble member over the test area, the first ( MM-1)consisted of all three EPS, the second (MM-2) consisted of the ECMWF andNCEP EPS.The results demonstrate the level of correspondence between deterioration inpredictive skill and extended lead time. Compared with observations and witha lead time of one day, ECMWF performs a little better than other centre's.With over five days in advance, all the three EPS and the two MM EPS don'tgive reliable probabilistic precipitation forecasts. Both MM EPS canoutperform CMA and NCEP for most of the forecasted days, but still perform alittle worse than ECMWF. Though variation of daily percentile precipitationand ROC areas show MM-2 outperforms MM-1, gamma distribution indicates muchsimilar performances for all 10-day forecast, and neither is superior toECMWF.