泛相似预报法在汛期降水预报中的应用

文中分析了中国汛期降水的最佳相似情况,将传统的相似方法推广为包含有相似和反相似两个方面,得出近23a的最佳相似的距平相关系数(ACC)可以达到0.382。在此基础上提出泛相似预报的方法。利用近23a降水资料试验,表明泛相似的汛期降水预报评分的ACC可达0.130。

PAN-SIMILARITY METHOD AND ITS FORECAST EXPERIMENTS ON SUMMER PRECIPITATION IN CHINA

The similarity prediction method has been adopted extensively in short-rang climate prediction for many years, the best similarities of Chinese summer precipitation have been analyzed and discovered that the anomaly correlation coefficient (ACC) of the best similarity of recent 23 years can achieve at 0.382, which is far higher than other methods, and can be regarded as the upper limit of similarity prediction. Its prediction accuracy is about 70%, lower than the theoretically limitation of seasonal precipitation forecast. The traditional similarity method has been extended to the extensive similarity one, or called pan similarity method. The extensive one contains the both of plus and negative similarity. When the anomaly correlation coefficients of the former fields such as temperature, height of 500 hPa are negative, the prediction should also be negative. The various results have been got through the various fields, and the last one is the mean of them. The experiments of recent 23 years indicate that the forecasting score (ACC) reaches 0.130,which is higher than the multi-year mean one. But the good effect cannot be got in every year, maybe only one similar criterion used. So other criterions such as distance function can be used as another one to improve the prediction level. It is obvious that the method has good application value in active operation. As present forecast level is not high, the statistic forecast research should not be abandoned while developing the numerical model in the short-rang climate prediction.