最优插值法在对中国自动站降水量空间分析中的参数优化

探讨了利用最优插值对中国3万多个自动站小时降水数据进行空间分析时核心参数(数据信噪比、相关随距离的变化关系等)的优化和确定方法,其中优化的数据信噪比约为0.3,相关随距离增加呈e指数递减关系。研究表明:当站网密度差异较大时,通过确定影响台站数来进行空间插值,一方面可以提高站点稠密区的插值效率,另一方面可以提高站点相对稀疏区的插值精度。另外,探讨了最优插值中初估场对插值结果地影响,认为采用气候标准值生成的初估场能显著降低插值结果的随机误差,其结果比采用同时刻的降水分析场作为初估场更稳定。

Parameter Improvements of Hourly Automatic Weather Stations Precipitation Analysis by Optimal Interpolation over China

Optimal Interpolation method(short for OI) is one of common ways to precipitation analysis.In this paper,the key parameters in OI such as signal to noise ratio,changing relationship between precipitation correlation coefficient and distance at any two observed points is determined.The research results indicate that 1) the optimized signal to noise ratio is about 0.3;2) the correlation coefficient of precipitation at two points is a function of its distance with exponential decrease;3) the number of influencing stations is an effective index when the gauge density is relatively inhomogeneous as the distribution of Automatic Weather Stations over China,which can improve the interpolation efficiency over the dense gauged areas and increase the interpolation accuracy over the sparse gauged areas;4) taking the climatological standard analysis as the first-guess field can effectively reduce the random error in OI and tends to present more stable results than the simultaneous first-guess field.