The Prediction of Summer Precipitation and Winter Temperature over Xinjiang

The operational prediction ability of summer precipitation and winter temperature over Xinjiang is studied with the common techniques including seasonal models,multi-model ensemble,statistical downscaling,statistical methods,ensemble of both downscaling and statistical methods.The operational seasonal models from National Climate Center,ECMWF,NCEP,JMA,two muliti-model ensemble methods(the average and super-ensemble), three downscaling methods(BP-CCA,EOF-ITE,HCRE) and three statistical methods(BP-CCA,OCN,HCRE) used in National Climate Center are employed in this paper.Our study shows that the above techniques and methods have much different prediction abilities on the summer precipitation and winter temperature over Xinjiang. The skill scores of the leading operational seasonal models are very low. Meanwhile, the super-ensemble of models and downscaling methods are often better than single model while the best downscaling method shows higher score than the best multi-model ensemble method. Besides,the skills of statistical methods are similar to the downscaling ones. The super-ensemble of both downscaling and statistical methods often holds quite higher prediction accuracy. What is more, it is indicated that the common methods used in present operation are of certain ability on the prediction of the trend but of few ability on the spatial distribution of the climate anomalies over Xinjiang. It is suggested that the technique on seasonal prediction over Xinjiang should be developed focusing on the ensemble of statistical and downscaling methods.