非线性风场的VAD分析初探

VAD ElEMENTARY ANALYSIS OF NONLINEAR WIND FIELD

本文对非线性风场的 VAD技术 ,从理论上进行了比较详细的分析 ,并对非线性风场中的非线性判断、非线性模型建立以及提取测站上空风向风速做了讨论。分析表明 ,均方根误差 RMS可作为风场线性与否的判据 ,若用二阶及其以下谐波拟合 ,且拟合 RMS<1.5 m/ s,则认为该风场为线性 ,否则为非线性 ;而且RMS≤ 1.5 m/ s可以用来确定该非线性风场多项式描述的程度 。

Analyzing linear wind field by the convention VAD, we can obtain directly the mean divergence, the mean deformation, the mean horizontal wind or the components of the wind field at the center of the scanned circle. If the actual wind is nonlinear, it is different in the theory, the convention VAD analysis can not provide directly the above-mentioned components at all. In this paper, we considered the general form of a nonlinear wind in application of the VAD method. It includes testing of nonlinear of observations, determining the nonlinear model(range depends of the F coefficients), and using the least-squares fit in range to obtain the components of the wind. The case analysis of single-Doppler observations shows that the deviation of the result is small to the standard of linear wind observations at the same height and time, relative error is from 15 % to 17 %. The developed VAD method is reasonable to the nonlinear wind.