气候预测PS评分对业务影响  

The Impact of PS Method on Operational Climate Forecast

作　　者：田武文[1] 吴素良[1] 王娜[1] 

机构地区：[1]陕西省气候中心,西安710015

出　　处：《应用气象学报》2010年第3期379-384,共6页Journal of Applied Meteorological Science

摘　　要：通过对中国气象局现行PS评分办法与理论PS评分的对比,发现现行评分办法对理论PS评分进行了两处修改。一处修改是扩大了预报正确的评定范围,但在PS评分办法实施后,在气候预测业务中,却出现了只预报2个等级的普遍现象,即在能获得高分的同时却降低了预报能力。另一处修改是按统一的要素距平划分等级,结果出现了预报对象的等级分布随着测站、月份变化而变化的现象。预报对象的等级分布是无技巧预报评分的决定因素,而预报技巧是由PS评分与无技巧预报评分之差决定的。在无技巧预报评分有差异的情况下,不同月份、不同区域之间的PS评分便失去了对比的基础。该文针对上述问题,对现行PS评分办法提出了修改建议。In the operation of climate forecast,scoring methods of PS,SS,ACC are widely used.Among them, SS and ACC,known as technique scores,are defined as the similarity between forecast and realistic results when comparing with non-technique forecasts or the expectations of non-technique forecasts equal to zero. The technique scores are basically originated from the evaluations in the forecast results from different populations and thus provide a basis for impartial comparisons.However,PS is considered as the concordance of forecast grades and are not compared with technique scores,so PS is not technique scores.In China, PS is of greater importance in climate forecasts.The PS of short-term climate forecasts by each province are performed every year in the China Meteorological Administration and the ranks of monthly precipitation, mean temperature and total forecasting ability are released.The impact of present PS method used on the climate forecast is analyzed.The results show that the theoretical PS is a score of consistence rate based on accurate forecasts on the grades;the foundational requirement of the PS inter-comparison is that they share the same probability distribution in ranking.Through comparisons between the present and theoretical PS method,it＇s also found that the present scoring method is taken as the theoretical scoring method with two modifications which makes the present PS method actually become the concordance of weighted anomalies.The first revision has extended the range of forecast accuracy assessment,in which level 1,2,5 and 6 have extended to three grades,level 3 and 4 have extended to four grades,and weight coefficients are added for abnormal grades.However,only two grades are forecasted in climate operational forecast after PS method performs.Based on the examples of the annual precipitation extremes occur in Shaanxi Province,the random forecasts on level 2 and 6 are evaluated and compared.The results show that 2-level forecasts can score higher,while reducing the forecast capability.Another

关 键 词：月气候预测 PS评分 无技巧预报 预报正确评定范围 等级分布 

分 类 号：P456.1[天文地球—大气科学及气象学]