Depolarization Estimates from Linear H and V Measurements with Weather Radars Operating in Simultaneous Transmission-Simultaneous Receiving Mode
Depolarization Estimates from Linear H and V Measurements with Weather Radars Operating in Simultaneous Transmission-Simultaneous Receiving Mode
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使用同时传输-同时接收模式运行的气象雷达进行线性 H 和 V 测量来估计去极化
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发表时间：
2004
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通讯作者：
Sergey Y. M Atrosov
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作者：
Sergey Y. M Atrosov
圆退偏振比（CDR）是一个偏振参数，它不像线性退偏振比（LDR），不表现出显着的依赖于水凝物的方向，并可以用于粒子类型识别和形状估计，如果传播影响很小。水平和垂直极化信号的同时发射和同时接收（STSR）测量方案广泛用于研究和作战雷达。STSR方案不提供去极化的直接测量。本研究提出一种从雷达接收机中的STSR复电压获得去极化比的估计方法。如果发送时的相移B等于6908，并且接收时的相移g等于2 B，则该估计器提供真实的CDR。即使不满足这些条件，如果B 1 g 5 08，去极化估计仍然是可能的（尽管这样的估计稍微偏离真实CDR，在CDR和倾斜-458 LDR之间变化）。和B 1 g表示初始差分相移偏移并且可以被考虑。用NOAA X波段雷达的数据说明了这种去极化估计器的使用。在冰云中的测量表明，近CDR估计的效用，以确定树枝状晶体和云内逐渐聚集。还给出了近CDR估计在雨的插图。STSR模式中去极化估计的一个重要优点是这些估计是从两个“强"信道返回获得的。与利用直接去极化测量作为在表示两个正交极化的“强"和”弱"接收信道中测量的雷达回波的功率比的雷达系统相比，这大大放宽了雷达灵敏度要求。
Circular depolarization ratio (CDR) is a polarimetric parameter, which, unlike linear depolarization ratio (LDR), does not exhibit significant dependence on hydrometeor orientation and can be used for particle type identification and shape estimation if propagation effects are small. The measurement scheme with simultaneous transmission and simultaneous reception (STSR) of horizontally and vertically polarized signals is widely used with research and operational radars. The STSR scheme does not provide direct measurements of depolarization. This study presents an estimator to obtain depolarization ratios from STSR complex voltages in radar receivers. This estimator provides true CDR if the phase shift on transmission, b, is equal to 6908 and the phase shift on reception, g, equals 2b. Even if these conditions are not satisfied, depolarization estimates are still possible if b 1 g 5 08 (though such estimates deviate slightly from true CDR varying between CDR and slant-458LDR). The sum b 1 g represents the initial differential phase shift offset and can be accounted for. The use of this depolarization estimator is illustrated with the data from the NOAA X-band radar. The measurements in ice clouds demonstrate the utility of near-CDR estimates to identify dendritic crystals and their gradual aggregation within the cloud. Illustrations are also given for near-CDR estimates in rain. An important advantage of depolarization estimates in the STSR mode is that these estimates are obtained from two ‘‘strong’’ channel returns. This greatly relaxes the radar sensitivity requirements compared to radar systems that utilize direct depolarization measurements as the power ratio of radar echoes measured in ‘‘strong’’ and ‘‘weak’’ receiving channels that represent two orthogonal polarizations.