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种新的快速部署、双极化、双频c波段轮上雷达（CROW）。CROW具有创新的设计，可以快速部署，占地面积小，并具有深入观察强降水的能力。该雷达系统将提供NSF所需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调查途径，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（5cm波长）雷达比x波段（3cm波长）雷达更能观测强降水，x波段（3cm波长）雷达是典型的移动设备，包括多普勒轮上雷达（DOWs），目前是美国国家科学基金会低层大气观测设施的一部分。CROW无需预先准备场地，也可用于教育项目，允许学生使用波长更长、波束宽度更细的雷达来观察包含强降水的现象。它将被设计为可供没有经验的学生操作，以促进实践学习的机会。CROW将是一种影响深远的外联和展示工具，不仅可以方便、快速、廉价地用于大学/学院的教育任务，还可以用于节日、博物馆和相关场所。CROW移动雷达采用创新设计，避免了现有雷达固有的分辨率和尺寸之间的妥协。CROW将具有1度的波束宽度和快速扫描，独立的双频率允许高空间和时间分辨率。双偏振能力，加上独立的频率，将允许精确测量差反射率（ZDR），从中确定液滴类型，扫描速度是单频雷达的两倍。CROW将配备两个1兆瓦的发射机，以比任何现有的移动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将建造在一辆定制设计的拖车上，其中包括一台用于现场组装雷达天线的小型起重机，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设置和组装估计需要大约两个小时，使该系统适合观察可预测的事件，但不适合瞄准迅速演变的现象，如龙卷风。

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.