气象场观测误差和四维同化数值模拟试验

本文对气象观测中的随机误差和四维同化进行了数值摸拟试验。用五层原始方程模式,以1975年4月19日20时的观测资料作初始场进行六天预报。把每小时的预报结果贮存起来,作为没有误差的“真实大气观测资料”,然后在原来的初始场上加上一个随机误差场,用一个物理过程比前者稍差的同样模式进行数值预报,把“真实资料”不断嵌入模式中去进行四维同化试验。 误差场是用概率统计中产生伪随机数的办法产生以模拟观测误差的随机情况。 四维同化的试验结果表明:最优同化频率,不仅与观测资料误差有关,而且还与整个同化过程的长短有关。

NUMERICAL EXPERIMENTS OF OBSERVATIONAL RANDOM ERRORS AND FOUR-DIMENSIONAL DATA ASSIMILATION

In this paper, a five-level primitive equation model was used for numerical experiments of observational random errors and four-dimensional data assimilalion. The random error field was generated point by point by the method used to generate pseudorandom number in probability theory. The results show that the optimal assimilation frequency depends not only on the observational errors, but also on the duration of the whole assimilation process.