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| A Bayesian Scheme for Probabilistic Multi-Model Ensemble Prediction of Summer Rainfall over the Yangtze River Valley |
| LI Fang,ZENG Qing-Cun,LI Chao-Fan |
| Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029,Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029,Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029; Graduate School of Chinese Academy of Sciences, Beijing 100049 |
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Abstract A Bayesian probabilistic prediction scheme of the Yangtze River Valley (YRV) summer rainfall is proposed to combine forecast information from multi-model ensemble dataset provided by ENSEMBLES project. Due to the low forecast skill of rainfall in dynamic models, the time series of regressed YRV summer rainfall are selected as ensemble members in the new scheme, instead of commonly-used YRV summer rainfall simulated by models. Each time series of regressed YRV summer rainfall is derived from a simple linear regression. The predictor in each simple linear regression is the skillfully simulated circulation or surface temperature factor which is highly linear with the observed YRV summer rainfall in the training set. The high correlation between the ensemble mean of these regressed YRV summer rainfall and observation benefit extracting more sample information from the ensemble system. The results show that the cross-validated skill of the new scheme over the period of 1960 to 2002 is much higher than equally-weighted ensemble, multiple linear regression, and Bayesian ensemble with simulated YRV summer rainfall as ensemble members. In addition, the new scheme is also more skillful than reference forecasts (random forecast at a 0.01 significance level for ensemble mean and climatology forecast for probability density function).
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Received: 22 June 2009
Revised: 02 September 2009
Accepted: 10 September 2009
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