The fourth error contamination mechanism in numerical simulation studies

In this paper, it has been put forward a viewpoint which there exists the fourth error contamination mechanism in numerical weather forecasting models. In order to verify the existence of the mechanism, a non-uniform continuousity (NUC) index has been defined. The geographic distribution of the NUC have been calculated based on both the data of the real field and simulated field of the geopotential height at 500 hPa by T213 model of European Center of Mediuam range Weather Forecasting (ECMWF). The results show us that although the T213 model of ECMWF has a good performance on the prediction of the geopotential height field at 500 hPa with high accuracy, the changes in essence have happened: The area of non-uniform continuity in the simulated field is remarkably less than the real fields especially for those regions located at high pressure ridge and low latitude belt.