北京地区中尺度数值业务预报的客观检验
OBJECTIVE VERIFICATION ON NUMERICAL OPERATIONAL FORECASTING SYSTEM IN BEIJING
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摘要: 对北京地区中尺度数值天气预报客观检验系统的框架和方法进行了详细的介绍,分析了北京地区冬季(2001年11月1日~2002年2月28日)主要预报要素的客观检验结果,在此基础上给出北京地区冬季中尺度数值预报业务的误差特征,并根据检验结果定性地分析了模式预报系统性和非系统性误差的可能来源。结果表明,模式地形的强迫作用是地面和对流层低层预报系统性误差的重要来源;测站高空预报要素的非系统性误差显著,初始时刻存在的误差在积分过程中被进一步放大;对北京 (54511) 单站地面要素预报的检验结果发现,2-m温度预报冬季整体偏低。在系统性误差为主要误差分量时对模式的平均误差进行订正能有效地提高温度预报的准确率。Abstract: 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.
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表 1 测站的平均误差 (BIAS) 和均方根误差 (RMSE)
表 2 北京 (54511) 站2-m温度和10-m风速平均误差 (2001年11月1日~2002年2月28日)
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