改善EVAD技术求解散度的方法

AN IMPROVED METHOD OF EXTENDED VELOCITY-AZIMUTH DISPLAY ANALYSIS TO ENHANCE ACCURACY OF HORIZONTAL DIVERGENCE

摘要: 详细介绍了改善EVAD技术中测量水平散度的方法，用Sirmans建议的技术来模拟降水回波信号，通过此方法对模拟的含有0, 1, 2, 3阶谐波的非线性风场加噪声, 得到近于真实的多普勒速度场，并用此速度场得到的水平散度和以前的EVAD算法（Srivastava算法和Thomas算法）的水平散度相比较，结果表明：无论在非全方位不均匀采样、非全方位均匀采样、不同信噪比、不同速度谱宽条件下，文章建议的EVAD方法求得的水平散度精度有明显的提高。
- EVAD算法;
- 数值模拟;
- 权重函数
Abstract: ?The method that have improvements to the previously reported EVAD technique to obtain horizontal divergence are discussed in detail. Sirmans' method of radar simulated precipitation signal is applicable to the nonlinear wind field including the three harmonic, and a Doppler velocity field is obtained that is approximated to the real velocity field. The improved EVAD method, Srivastava's and Matejke's EVAD methods are applicable to this simulated Doppler velocity field, and three methods are compared. Computing results indicate that the accuracy of horizontal divergence is obtained by the improved EVAD method is enhanced at not full azimuth wind field, at different v and SNR.
- EVAD method;
- Numerical simulation;
- Weighting function

图 1 径向速度V_r为11 m/s (即对应的多普勒频率f₀为120 Hz, 速度谱宽σ_v为2 m/ s) 时, 附加40 dB信噪比 (SNR=40 dB) 白噪声后的离散功率谱密度图 (其中Nyquist频率F_n=256 Hz)

下载: 全尺寸图片幻灯片

表 1 模拟含0, 1, 2, 3阶谐波的非线性风场的特征参量

表 2 不同SNR条件下, 3种EVAD算法的结果对比

表 3 不同谱宽条件下, 3种EVAD算法的结果对比

表 4 不同非连续性缺口的条件下, 3种EVAD算法的结果对比

表 5 缺口范围相同但位置不同的条件下, 3种EVAD算法的结果对比

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