动力-统计客观定量化汛期降水预测研究新进展

Recent Progress on the Objective and Quantifiable Forecast of Summer Precipitation Based on Dynamical-statistical Method

汛期降水预测是短期气候预测的重要内容之一,也是难点之一。近20年来,动力-统计相结合的预测方法在解决这一复杂的科学难题方面取得了一定进展。该文系统地介绍了近年来国家级气候预测业务中关于动力-统计客观定量化预测的原理、最优因子订正和异常因子订正两类预测方案,及动力-统计集成的中国季节降水预测系统(FODAS1.0)。2009—2012年的汛期降水预测中,动力-统计客观定量化预测方法 4年平均PS评分为73,距平相关系数为0.16,体现了较高的预报技巧。但该方法仍存在不足,需通过加强气候因子与降水之间关系的诊断分析、完善短期气候模式的物理过程、改进参数化方案及研发有针对性的区域气候模式等手段,进一步提高模式本身的预报技巧,使动力-统计预测方法在汛期降水预测中发挥更大作用。

Short-term climatic prediction, which mainly aims at monthly, seasonal and annual time scales, is ver- y important for the public and government decision making. The trend of summer flood and drought distri- bution is one of the most important contents in operational forecastl Generally, there are two types of forecasting methods, including statistical method and dynamical method, which both have advantages and disadvantages. Therefore, the general consensus is to let them learn from each other, merging and develo- ping. During recent 50 years, the Dynamical-Statistical Integration Forecasting Method （DSIFM） has made great progresses in dealing with the complex scientific issue of summer precipitation forecasting in China and abroad. The research results in early period and the development about DSIFM are briefly reviewed, as well as the two forms of dynamical-statistical integration forecasting method. And then, the principle, processes and programs of Dynamical-Statistical Objective Quantitative Forecasting （DSOQF） in recent operational forecast are systematically introduced. Based on the Coupled Global Circulation Model （CGCM） of Nation- al Climate Center and two types of prediction scheme of DSOQF, a dynamical-statistical integrated forecas- ting system for seasonal precipitation （FODAS1.0） is set up, which fully assimilates existing research and profession achievements, especially forecaster diagnostic techniques and forecasting experience from na- tional, regional and provincial climate centers. Suitable regional climate characteristics prediction scheme is also developed based on the theory and methods of DSOQF. By now, FODAS1.0 achieves quasi-operation- al trial in National Climate Center, 8 regional climate centers and Guangxi, Shandong and other provincial climate centers. Experimental predictions are carried out for the summer rainfall in China from 2009 to 2012 with the method of DSOQF. The predictive score （PS） from 2009 to 2012 are 79, 72, 70 and 70, respectively. The anomaly correlation coefficient （ACC） from 2009 to 2012 are 0.38, 0.10, 0.12 and 0.03. For abnormal years such as 2010 and 2011, diagnostic analysis is performed. Overall, the forecast results are ideal, but it still needs further improving. The problems in DSIFM and the solutions are also discussed. The forecasting skills can be improved by strengthening diagnostic analysis of the relationship between precipitation and its main factors, impro- ving the physics processes and parameterization scheme of short-term climate models, and developing the targeted regional climate models. The DSIFM will be more useful in the future.