OBJECTIVE VERIFICATION ON NUMERICAL OPERATIONAL FORECASTING SYSTEM IN BEIJING

Structure and methods of the objective verification system on operational numerical weather forecasting in Beijing area are introduced in detail. On the base of the analyses on verification results of main forecasting products in the winter of 2001 (from 1st Nov. 2001 to 28th Feb. 2002), the characteristics of error distribution of operational numerical forecast in Beijing area are shown. In addition, the systematic and non-systematic errors' possible sources in operational numerical forecast are analyzed. It suggests that the Bias errors revealed by grid verification appear to reflect the influence of topographic features on surface and mid-troposphere variables forecasts. Also, for upper-air forecasts, nonsystematic error caused by inconsistent resolution of scales between the forecasts and observation is a more important component. The initial errors usually propagate into the forecast. Utilizing a simple mean error correction could eliminate part systematic error.