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A simple biota removal algorithm for 35GHz cloud radar measurements

机译:35GHz云雷达测量的简单Biota去除算法

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摘要

Cloud radar reflectivity profiles can be an important measurement for the investigation of cloud vertical structure (CVS). However, extracting intended meteorological cloud content from the measurement often demands an effective technique or algorithm that can reduce error and observational uncertainties in the recorded data. In this work, a technique is proposed to identify and separate cloud and non-hydrometeor echoes using the radar Doppler spectral moments profile measurements. The point and volume target-based theoretical radar sensitivity curves are used for removing the receiver noise floor and identified radar echoes are scrutinized according to the signal decorrelation period. Here, it is hypothesized that cloud echoes are observed to be temporally more coherent and homogenous and have a longer correlation period than biota. That can be checked statistically using ~4s sliding mean and standard deviation value of reflectivity profiles. The above step helps in screen out clouds critically by filtering out the biota. The final important step strives for the retrieval of cloud height. The proposed algorithm potentially identifies cloud height solely through the systematic characterization of Z variability using the local atmospheric vertical structure knowledge besides to the theoretical, statistical and echo tracing tools. Thus, characterization of high-resolution cloud radar reflectivity profile measurements has been done with the theoretical echo sensitivity curves and observed echo statistics for the true cloud height tracking (TEST). TEST showed superior performance in screening out clouds and filtering out isolated insects. TEST constrained with polarimetric measurements was found to be more promising under high-density biota whereas TEST combined with linear depolarization ratio and spectral width perform potentially to filter out biota within the highly turbulent shallow cumulus clouds in the convective boundary layer (CBL). This TEST technique is promisingly simple in realization but powerful in performance due to the flexibility in constraining, identifying and filtering out the biota and screening out the true cloud content, especially the CBL clouds. Therefore, the TEST algorithm is superior for screening out the low-level clouds that are strongly linked to the rainmaking mechanism associated with the Indian Summer Monsoon region's CVS.
机译:云雷达反射率曲线可以是对云垂直结构(CVS)的调查的重要测量。然而,从测量中提取预期的气象云内容通常需要一种有效的技术或算法,其可以减少记录数据中的误差和观察不确定性。在这项工作中,提出了一种技术来使用雷达多普勒光谱矩测量来识别和分离云和非水力计仪回波。基于目标的基于目标的理论雷达灵敏度曲线用于去除接收器噪声底板,并且根据信号去相关周期仔细审查所识别的雷达回波。这里,假设云回波被观察到时间更加连贯和均匀,并且具有比Biota更长的相关时间。可以在统计上使用〜4S滑动平均值和反射率概况的标准偏差值进行统计检查。上述步骤通过滤除Biota批判密地筛选云。最后的重要一步争取云高度的检索。所提出的算法可能仅通过局部大气垂直结构知识来通过系统表征Z变异性的系统表征,并且除了理论,统计和回波跟踪工具之外,通过Z变异性的系统表征。因此,已经采用了高分辨率云雷达反射曲线测量的表征,并对真实云高度跟踪(测试)观察到的回声统计。测试表明筛选云层和滤除孤立的昆虫的卓越性能。发现具有偏振测量的测试在高密度Biota下更有前途,而测试与线性去极化比和光谱宽度相结合,可能会在对流边界层(CBL)中的高湍流浅层云中过滤掉生物区域。这种测试技术在实现中具有很简单的简单,但由于约束,识别和过滤出Biota并筛选真正的云内容,尤其是CBL云的灵活性,因此性能强大。因此,测试算法优于筛选出与与印度夏季季风区的CV相关联的雨制机械相关的低级云。
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