利用湍流作数值分析及数值预报中的平滑化过程

SMOOTHING PROCEDURE IN NUMERICAL ANALYSIS AND FORECASTING REALIZED BY TURBULENCE PROCESS

摘要: 在高空大范围流型的数值预报中技术上的困难问题之一就是如何消去原始高度场或预报高度场里的小扰动.这种小扰动不论是真的,还是假的(原始场中的观测误差,预报场中的截平误差(Truncation error),地转风假定下原始小扰动的虚假发展等等),都不是预报的对象,因此必须用种种平滑化过程设法除去.

Abstract: It is pointed out in this note that the procedure of smoothing according φ*=φ+kφ,( the finite difference Laplacian) used in numerical analysis and fore-casting, after every time step, is equivalent to introducing the turbulence term with k=AΔt/(Δs)2,where A is the austausch coefficient, Δt the time step and Δs the horizontal grid-size.