地面观测资料特征的初步分析

Preliminary Analysis on Surface Observational Data Assimilation

从分析常规地面观测资料的特点入手,研究我国地面观测站的分布特点,分析模式地形与站点地形高度误差的差异程度。结果表明,我国2 872个地面观测站点在全国范围内分布不均匀,大体上呈东多西少的分布;大部分观测站点分布在站点高度低于500 m的、土地面积仅占国土面积约27.0%的地区;站点地形和模式地形存在高度误差,绝大多数站点的模式地形高于站点地形,所有观测站与模式地形的高度误差均值为130.76 m,有的站点的差值达1 000 m以上;模式地形与站点地形的高度差异程度分布很不均匀;根据Ruggiero同化方案,对地面观测资料进行初步筛选,不到40.0%的观测资料进入模式底层,导致地面观测资料利用率较低。

Starting from analyzing characteristics of conventional ground observation data,the distribution characteristics of ground observation station were studied,the difference between the terrain and the height error of the site was analyzed. The results showed that there are 2 872 ground observation stations all around our earth land,while these stations are very unevenly distributed. Taking it by and large,the distribution situation of the ground stations shows that stations in the west of China are less than ones in the east of China. According to the statistical results,most of the ground stations distribute in areas lower than 500 meters in surface observation station measurement,which take up only 27 percent of total areas. There exists elevation difference between surface observation station measurement and numerical model surface. The numerical model surface elevation of most surface observation stations is higher than elevation in surface observation station measurement. The medium value of elevation difference is about 130. 76 meters,especially some difference value reach to above 1 000 meters. Making use of Ruggiero＇s approach to preliminarily filter surface observation data,we just find that less than 40 percent of surface observation data can fall under the bottom of the numerical model. That is to say,the availability of all the observation data is quite low.