数值预报同化系统中观测资料误差分析

在观测资料同化系统中,观测误差均方差与背景场误差均方差共同决定着观测信息与背景场信息的相对重要性以及这些信息在空间及不同变量间的扩展方式,故在资料同化系统中起到决定性作用.因此,观测误差均方差的合理估计是非常重要的.采用贝塞尔函数拟合方法,从探空观测资料与背景场的偏差(IV)协方差中分离出探空资料的观测误差均方差与模式的背景场误差均方差;再从其他观测资料偏差协方差中扣除背景场误差均方差来估计其它观测误差均方差.观测误差均方差分析使用2006年8月1-31日观测资料,国家气象中心T213L31全球中期分析预报系统的6小时预报作为背景场.结果显示估计的观测误差均方差是比较合理的.

Analyses of Observation Data Error in Numerical Forecasting Assimilation System

It is important to suitably estimate the root mean square of observation error i n a given assimilation system. Firstly, by using Bessel fitting method, the root mean square of observation error and root mean square of first guess error are separated from the covariance of the deviation of radio sounding observation an d first guess. Then the root mean square of other observation error for other ob servation types are estimated by deducting the root mean square of first guess e rror from the covariance of the deviation of radio sounding observation and fir st guess. The observation data during 1-31, August 2006 and the first guess from T213 numerical weather prediction system are used for analyzing the root mean s quare of observation error. The results show that the estimated root mean square of observation error for each observation type is reasonable.