检验全球数值预报模式的相似度等指标

Similarity and distance for verification of global numerical models

本文依照泛函形式并考虑了球面经纬网格的特点,定义了用于全球数值模式效果检验的指标:距离、距平相似度和倾向相似度,给出了相应的计算方法,并以全球WRF模式为例,检验了该模式的中期预报效果。所得结论如下:指标距离、距平相似度和倾向相似度物理意义明确,易于理论分析,考虑了球面经纬网格的特点,检验准确度高,具有普适性,能方便应用于球面经纬网格输出的数值模式检验。指标距离、距平相似度的检验结果分别与传统检验指标均方根误差、距平相关系数相一致,该指标还可直接用于向量场(如风场)的整体检验。本文的全球WRF模式所做的检验表明,对本文个例,该模式的全球500 hPa中期天气形势预报在第7 d及之内皆可用,5 d及之内预报效果更佳。

The new statistics for verification of global numerical models,distance,anomaly similarity and tendency similarity are introduced in functional way in this paper and takes the global characteristics into consideration. The effect of the three indexes for global numerical models is verified and the corresponding calculation method is given in the paper. The forecast results of global WRF model are taken as an example to evaluate its ability to predict weather system of medium-range. Results show as follows：the new statistics have explicit physical meanings,convenient for theoretical analysis and taking the characteristic of numerical model with spherical meridian grid into consideration. Thus,they have high accuracy and are universal. They can be easily used for verification of numerical models with output in spherical latitude and longitude grid. The calculation results of new statistics are compared with typical statistics（anomaly correlation coefficient and root-mean-square error,which are suggested by World Meteorological Organization）. The calculations of new statistics are consistent with that of typical ones. The new statistics can also be used for the verification of vectors,like wind field. The calculation results of new statistics of global WRF show that the prediction of global geopotential height is usable in seven days and better in five days for the example in this article.