Millimetre-wave radar measurement of rain and volcanic ash
Millimetre-wave radar measurement of rain and volcanic ash
复制标题
降雨和火山灰的毫米波雷达测量
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Peter J. Speirs
中科院分区：
文献类型：
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作者：
Peter J. Speirs
本文介绍了利用水平指向毫米波雷达测量降雨率的各种方法的发展。这项工作建立在T矩阵散射模型和液滴形状模型的组合基础上，T矩阵散射模型允许计算几乎任意轮廓的旋转对称粒子的散射，液滴形状模型允许考虑温度和压力对形状的影响。用38 GHz和94 GHz的FMCW雷达以及圆盘测量仪和气象站收集了长达数小时的降雨数据。这些已被用来开发测量降雨率的单频和双频技术。在38 GHz处成功地证明了反射率与降雨率之间简单的幂定律关系在温度、偏振和衰减方面的修正应用。然而，在94 GHz，已经发现更详细的关于反射率、衰减和降雨率的函数是有益的。一种基于反射率的衰减测定方法被改编自文献，并成功地应用于94 GHz数据，改进了对较长距离的降雨率的估计。在基于38 GHz和94 GHz消光系数之比的双频技术中，也使用了同样的方法来估计衰减，但不太成功。然而，基于双频反射率的方法已经被成功地开发和应用，产生了对降雨率的良好估计，以及对两个雨滴尺寸分布参数的合理估计。对空中火山灰的雷达测量也进行了模拟，表明对于最合理的测量配置，最佳频率通常是35 GHz或94 GHz，而不是更常用的3-10 GHz。它还表明，现有的各种毫米波雷达可以用来探测火山灰。最后讨论了火山灰双频测量的最佳频率。
This thesis presents the development of various methods for measuring rainfall rates using horizontally-pointing millimetre-wave radars. This work builds from the combination of a T-matrix scattering model that allows the scattering from almost arbitrarily profiled rotationally symmetric particles to be calculated, and drop shape models that allow the effects of temperature and pressure on the shape to be taken into account. Many hours of rain data have been collected with 38 and 94 GHz FMCW radars, as well as with a disdrometer and weather station. These have been used to develop singleand dual-frequency techniques for measuring rainfall rate. A temperature, polarisation and attenuation corrected application of simple power-law relationships between reflectivity and rainfall rate has been successfully demonstrated at 38 GHz. However, at 94 GHz it has been found that more detailed functions relating reflectivity, attenuation and rainfall rate are beneficial. A reflectivity-based determination of attenuation has been adapted from the literature and successfully applied to the 94 GHz data, improving the estimate of rainfall rate at longer ranges. The same method for estimating attenuation has also been used in a dualfrequency technique based on the ratio of the extinction coefficients at 38 and 94 GHz, but with less success. However, a dual-frequency reflectivity ratio based approach has been successfully developed and applied, producing good estimates of rainfall rate, as well as reasonable estimates of two drop-size distribution parameters. Simulations of radar measurements of airborne volcanic ash have also been carried out, demonstrating that for most reasonable measurement configurations the optimal frequencies would typically be 35 GHz or 94 GHz, not the more commonly used 3-10 GHz. It has also been shown that various existing millimetre-wave radars could be used to detect ash. Finally, there is a discussion of the optimal frequencies for dual-frequency measurement of volcanic ash.
用于环境遥感的 94 GHz 被动和主动成像
DOI：
10.1117/12.2015730
发表时间：
2013
期刊：
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影响因子：
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作者：
Macfarlane D
通讯作者：
Macfarlane D