Extended Application of a Novel Phase Calibration Approach of Multiple-Frequency Range Imaging to the Chung-Li and MU VHF Radars
Extended Application of a Novel Phase Calibration Approach of Multiple-Frequency Range Imaging to the Chung-Li and MU VHF Radars
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新型多频范围成像相位校准方法在 Chung-Li 和 MU VHF 雷达中的扩展应用
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
M. Zecha
中科院分区：
文献类型：
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作者：
Jenn;C. Su;Y. Chu;G. Hassenpflug;M. Zecha
多频范围成像 (RIM) 旨在提高雷达回波分布的距离分辨率，现已适用于最近升级的中立 VHF 雷达（24.98N、121.18E）。为了完成该雷达的 RIM 技术，采用了最初为 Ostsee Wind (OSWIN) VHF 雷达提出的一种新颖的相位校准方法，用于检查相位偏差和距离加权函数对接收的雷达回波的影响。估计的相位偏差表明雷达系统中信号的时间延迟为 1.83 毫秒。相反，从双频互相关函数的相位分布确定这样的时间延迟更困难。同样的校准方法也成功应用于中层和高层大气 (MU) 雷达（34.858N，136.118E），并显示所采用的雷达参数的时间延迟为 0.33 毫秒。各种雷达的这些校准结果证明了所提出的校准方法的一般可用性。凭借RIM的高分辨率性能，对流层中一些在高度-时间强度图中看不到的小尺度开尔文-亥姆霍兹（KH）波浪、双层结构和羽状结构在目前的观测中已经被识别出来。研究发现波浪和双层与强垂直风切变和小理查森数密切相关，支持了KH不稳定动态过程的假设。另一方面，观察到羽状结构是从波状层中生长出来的，这可能归因于重力波的饱和和破裂。这些精细结构显示出一些显着的特征，这些特征是通过应用于低层大气中的 VHF 雷达的 RIM 方法解决的。
Multiple-frequency range imaging (RIM), designed to improve the range resolution of radar echo distribution, is now available for the recently upgraded Chung-Li VHF radar (24.98N, 121.18E). To complete the RIM technique of this radar, a novel phase calibration approach, proposed initially for the Ostsee Wind (OSWIN)VHFradar,wasemployedtoexaminetheeffectsofphasebiasandtherange-weighting functionon the received radar echoes. The estimated phase bias indicated a time delay of ;1.83 ms for the signal in the radar system. In contrast, such a time delay is more difficult to determine from the phase distribution of twofrequency cross-correlation functions. The same calibration approach was also applied successfully to the middle and upper atmosphere (MU) radar (34.858N, 136.118E) and revealed a time delay of ;0.33 ms for the radar parameters employed. These calibration results for various radars demonstrate the general usability of the proposed calibration approach. With the high-resolution performance of RIM, some small-scale Kelvin‐ Helmholtz (KH) billows, double-layer structures, and plumelike structures in the troposphere that cannot be seen in height‐time intensity plots have been recognized in present observations. The billows and double layerswerefoundto beclosely relatedtostrongverticalwindshearandsmallRichardsonnumber,supporting the hypothesis of a dynamic process of KH instability. On the other hand, the plumelike structures were observed to grow out of a wavy layer and could be attributed to saturation and breaking of gravity waves. These fine structures have shown some remarkable features resolved by the RIM method applied to VHF radars in the lower atmosphere.