基于EMD方法的X波段双偏振雷达衰减订正

针对X波段双偏振雷达信号在降雨路径中的衰减现象，本文提出经验模式分解（Empirical Mode Decomposition，EMD）方法进行X波段双偏振雷达衰减订正，首先对总差分传播相移进行EMD分解得到有限个基本模式分量（Intrinsic Mode Function,IMF），并基于皮尔逊相关系数准则将IMF分为噪声IMF和信号IMF两类，然后对信号IMF进行有效重构得到差分传播相移，再将差分传播相移通过最小二乘法拟合得到差分传播相移率，最后对求得的差分传播相移与差分传播相移率采用自适应约束方法进行反射率衰减订正。利用EMD方法和其他方法进行对比分析，其结果表明，EMD方法能够有效地消除X波段双偏振雷达回波数据中后向散射的影响，在保留真实的气象信息的同时，有效地抑制差分传播相移的显著波动，进而衰减订正效果更好。

X-Band Dual-Polarization Radar Attenuation Correction Based on EMD Method

Aiming at the attenuation phenomenon of the X-band dual-polarization radar signal in the rain path, this paper proposes an empirical mode decomposition (EMD) method to correct the attenuation of the X-band dual-polarization radar. First, the EMD decomposition of the total differential propagation phase shift is performed to obtain a finite number of basic mode components (Intrinsic Mode Function, IMF), and based on the Pearson correlation coefficient criterion, the IMF is divided into two types: noise IMF and signal IMF. Then,the effective reconstruction of the signal IMF is done to obtain the differential propagation phase shift, and the differential propagation phase shift rate is obtained by the least squares fitting of the differential propagation phase shift. Finally, the calculated differential propagation phase shift and the differential propagation phase shift rate are corrected by an adaptive constraint method for reflectivity attenuation. Thecomparative analysis of EMD method and other methods shows that the EMD method can effectively eliminate the influence of backscattering in the X-band dual-polarization radar echo data. It effectively suppresses the significant fluctuation of the differential propagation phase while retaining the true meteorological information to achieve better attenuation correction effect.