基于天线贡献值的中频雷达水平风场短时突变改善方法

      Antenna Contribution based mitigation of short-term discontinuities in horizontal winds retrieved by MF radar

      • 摘要: 中频雷达是观测中间层至低热层区域水平风场的常规探测设备之一,其基于全相关分析法计算多根天线间接收信号的相关函数,并依据相关函数的幅度特性完成风场反演。实际观测中,系统硬件不稳定及空间探测区域干扰会导致相关函数幅度特性短时失真,使反演风场出现短时突变并使长期统计结果偏离物理特征。对此,现有工作主要围绕接收信号降噪展开,但业内普遍采用的多项式拟合方法对噪声敏感,短时杂噪波动易在反演中传播并引发风场短时突变,因此亟需引入与噪声水平不相关的指标指导降噪处理。本文受MST雷达启发,将天线贡献值作为参数指标引入MF雷达,提出MF-AH算法处理相关函数幅度失真,并通过数值仿真与MF雷达实测数据验证。结果表明,相比传统多项式拟合方法,MF-AH算法在信噪比为−5至20 dB范围内可有效改善因信噪比降低导致的风场短时突变,反演风场更符合中高层大气的物理规律与观测特征。

         

        Abstract: Frequency radar is one of the conventional instruments for observing horizontal wind fields in the mesosphere and lower thermosphere region. It calculates the correlation functions of signals received by multiple antennas based on the full correlation analysis method and retrieves wind fields according to the amplitude characteristics of the correlation functions. In actual observations, instability in the system hardware and interference in the spatial detection region can cause short-term distortions in the amplitude characteristics of the correlation functions, leading to abrupt short-term variations in the retrieved wind fields and causing long-term statistical results to deviate from physical characteristics. Existing work primarily focuses on denoising received signals, but the widely adopted polynomial fitting method is sensitive to noise. Short-term noise fluctuations can propagate during retrieval and cause abrupt wind field variations. Therefore, there is an urgent need to introduce noise-level-independent metrics to guide the denoising process. Inspired by MST radar, this paper introduces the antenna contribution value as a parameter metric into MF radar and proposes the MF-AH algorithm to address amplitude distortions in correlation functions. The algorithm is validated through numerical simulations and real MF radar data. Results show that, compared to the traditional polynomial fitting method, the MF-AH algorithm effectively mitigates short-term abrupt wind field variations caused by reduced signal-to-noise ratios within the range of −5 to 20 dB. The retrieved wind fields are more consistent with the physical laws and observational characteristics of the middle and upper atmosphere.

         

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