基于单多普勒雷达的光流法改进技术

本文对基于径向速度的光流法在实际应用中存在的误差进行了分析,并提出了有效的改进方案。合成数据试验结果表明:基于径向速度的光流法在反演低仰角(小于2.5°)数据和包含非线性变化的实际风场时存在较大的误差。在低仰角情况下,由于径向速度在垂直方向的分量非常小,导致垂直速度的反演包含较大的计算误差并影响水平速度的反演精度。而当实际风场存在较大非线性变化时(如锋面、切变线等),算法中的局部约束条件被破坏,导致切变区域反演精度降低或出现奇异值。针对这两种情况,本文提出了有效的改进算法。在低仰角情况下引入了简化的约束方程,并加入了径向速度一致性的约束条件来克服实际风场非线性带来的误差。通过理想数据试验和实际个例的检验发现,改进后的算法可以有效地提高风场反演的精度和应用范围。

An improved algorithm of optical flow from single doppler radar

The error of the optical flow based on the radial velocity in the practical application was analyzed and an improved scheme was given. The results of synthetic data experiments show that the optical flow based on the radial velocity has obvious errors when retrieving low elevation(less than 2.5°) data and nonlinear wind field. In the case of low elevation, the vertical component of radial velocity is quite small, so it will lead to computational errors of vertical velocity and influence the accuracy of horizontal velocity. And when the actual wind field is non-linear (such as front, shearling, etc.), the local constraint in the algorithm can''t meet and will lead to low precision or singular value in the shear area. Given the above two kinds of circumstances, an effectively improved scheme was given. The constraint equation in the low elevation was simplified and the constraint condition of radial velocity uniformity was added to overcome the effects of the nonlinear wind field. It is found that the improved algorithm can effectively improve the accuracy of the retrieved wind field and its application scope through the synthetic data experiments and practical application.