Construction of Mobile C-band, Narrow-Beam, Dual-Frequency, Dual-Polarization, High-Power Radar

恶劣天气研究中心将建造一个新的可快速部署的、双极化、双频C波段车载雷达（CROW）。CROW具有创新的设计，可以快速部署，占地面积小，并能够深入到强烈的降水中。这一雷达系统将提供美国国家科学基金会所要求的用户设施所缺乏的能力，并将在恶劣天气研究领域开辟新的研究途径，包括对流系统、热带和冬季风暴的测量以及大气边界层研究。C波段（5厘米波长）雷达比X波段（3厘米波长）雷达更有能力通过强降水进行观测，而X波段雷达是移动的设施的典型，包括目前属于国家科学基金会低层大气观测设施一部分的轮式多普勒雷达。 CROW不需要预先准备场地，也可用于教育项目，使学生能够使用波长较长、波束宽度较细的雷达观察包含强降水的现象。它将被设计为可操作的学生几乎没有以前的经验，以促进动手学习的机会。CROW将是一个高影响力的外展和展览工具，不仅可以方便、快速、廉价地部署到大学/学院的教育任务中，还可以部署到节日、博物馆和相关场所。CROW移动的雷达采用了创新的设计，避免了现有雷达固有的分辨率和尺寸之间的折衷。CROW将具有1度的波束宽度和快速扫描，独立的双频，以实现高空间和时间分辨率。 双偏振能力加上独立频率，将允许以单频雷达扫描速度的两倍精确测量差反射率（ZDR），从而识别液滴类型。CROW将配备两个1兆瓦的发射机，以便比任何现有的移动的C波段雷达对晴空和微弱的远距离信号具有更高的灵敏度，并可与通常用于气象应用的研究质量S波段（10厘米波长）系统相媲美。CROW将建在一个定制设计的拖车上，拖车上有一个小型起重机，用于现场组装雷达天线，从而能够运输C波段操作所需的12英尺直径的天线。雷达天线和相关结构的安装和组装估计需要大约两个小时，使该系统适合于观测可预测的事件，但不适合于观测龙卷风等迅速演变的现象。

The Center for Severe Weather Research will construct a new quickly deployable, dual-polarization, dual-frequency C-band Radar On Wheels (CROW). CROW has an innovative design that will allow rapid deployment, has a small footprint and conveys the ability to peer deeply into intense precipitation. This radar system will provide a capability that is lacking in NSF's requestable user facilities and will open new avenues of investigation in the areas of severe weather research, including measurement of convective systems, tropical and winter storms, as well as atmospheric boundary layer studies. C-band (5 cm wavelength) radar is more capable of observing through intense precipitation than the X-band (3 cm wavelength) radar that is typical of mobile facilities, including the Doppler on Wheels (DOWs) that are currently part of the NSF Lower Atmosphere Observing Facilities. CROW, requiring no advance site preparation, will also be deployable for educational projects, permitting students to use a longer-wavelength, fine-beamwidth radar to observe phenomena containing intense precipitation. It will be designed to be operable by students with little prior experience, to promote hands-on learning opportunities. CROW will be a high-impact outreach and exhibition tool, easily, quickly, and inexpensively deployed not only to university/college educational missions, but also festivals, museums, and related venues.The CROW mobile radar employs an innovative design to circumvent compromises between resolution and size that are inherent in existing radars. CROW will have a 1-degree beamwidth and quick scanning, independent dual frequencies to allow for high spatial and temporal resolution. Dual-polarization capability, coupled with the independent frequencies, will permit accurate measurements of differential reflectivity (ZDR), from which droplet type is identified, at twice the scanning speed of single frequency radars. CROW will be outfitted with two 1-megawatt transmitters to permit higher sensitivity to clear-air and weak distant signals than any existing mobile C-band radar and comparable to that of research quality S-band (10 cm wavelength) systems typically used for meteorological applications. CROW will be built on a custom-designed trailer that includes a small crane for assembling the radar antenna on-site, thereby enabling transport of a twelve-foot diameter antenna necessary for C-band operations. Set-up and assembly of the radar antenna and associated structures is estimated to take about two hours, making the system suitable for observation of predictable events, but not for targeting of rapidly evolving phenomena, such as tornadoes.