IAP PSSCA两组预测试验的评估及比较I.降水部分

Assessment and Comparison of Two Prediction Schemes of IAP PSSCA Part I: Precipitation

利用中国科学院大气物理研究所研制的短期气候距平数值预测系统 (IAPPSSCA) ,采用两种版本的大气环流模式 :AGCM 1 1和AGCM 1 2 ,分别以 2月 11～ 19日的 9天大气观测值为初始场 ,以给定海温为边界场 ,对 1980～ 1994年的 15年的降水异常进行了两组集合后报试验。对试验结果进行定量评估表明 :IAPPSSCA对降水异常具有一定的预测能力 ,特别是在中国东部受东亚季风及海温异常影响的地区 ,IAPPSSCA具有较高的预报技巧 ,其中以东南区域 (包括江淮流域和华南地区 )最高 ,尤其是对有洪涝灾害的降水异常年 ,距平相关系数在 0 50左右 ,接近可供业务使用的要求 ,说明模式能够抓住在东亚季风区存在的某种物理机制 ,从而提高了这一地区的预报技巧 ;另外 ,两个大气环流模式相比 ,改进了地表反照率的AGCM 1 2的 15年集合平均预测技巧略高于AGCM 1 1,特别是在华北地区 ,预测效果有明显提高 ,这表明改进地表反照率从而改进了模式的气候平均态的模拟 ,能提高气候模式的预测能力 ,说明较好的陆面过程引入模式对短期气候预测是有益的。

With the IAP Prediction System of Short-term Climate Anomaly (IAP PSSCA), two sets of seasonal and extra-seasonal ensemble hindcasts have been performed during the period of 1980～1994 in order to assess the prediction skill of the IAP PSSCA with two different schemes The difference of the two schemes is in the different version of AGCM used, with the IAP AGCM 1 1 in one scheme and the IAP AGCM 1 2 with an improved surface albedo parameterization in the other Comparisons of the hindcast results with the observations show that IAP PSSCA is capable of predicting the precipitation anomaly to some extent In the eastern China largely affected by Asian monsoon and SST anomalies, the prediction skill is relatively high, especially in the Southeastern China where the anomaly correlation coefficient can reach as high as 0 50 in the severe flood and drought years This may suggest that the possible mechanisms for these severe disasters have been well captured by the IAP PSSCA The prediction skill is higher for the modified model AGCM 1 2 as the model's climatological state is well simulated This indicates that models with reasonable land process will improve the prediction skill for short-term climate prediction