An Advanced Multi-Frequency Radar for Atmospheric Research

这是一项重大研究仪器奖，旨在支持为气象研究设计的便携式三波长扫描雷达的开发。它被称为先进多频雷达(AMFR)，由一个能够发射和接收Ku波段(13 GHz)、Ka波段(33 GHz)和W波段(95 GHz)频率的单一天线组成。(这些频率分别对应于2.2、0.91和0.32厘米的波长。)这三个雷达系统中的每一个都将能够进行多普勒和偏振测量。PI已经开发了一种名为云剖面雷达系统(CPRS)的双波长雷达，它在0.9厘米和0.3厘米处运行。该合同使第三部波长为2.2厘米的雷达得以增加，建造了一个新的天线，并将现有系统的灵敏度提高到0.9厘米和0.3厘米。该雷达的一个独特功能是馈电系统，旨在确保单个天线为三个波长产生配置一致的匹配波束。因此，所有波长的测量都将来自相同体积的云团。AMFR将高度便携，部署成本相对较低。应用将主要集中在云微物理领域。最初的重点将是冬季风暴中的层云和降水过程。雷达将能够探测到一些无降水的云，至少在较短的波长上是这样。此外，雨和雪在三个接收器上发出不同的信号，因为降水的偏振特性和瑞利散射的偏差都取决于波长。这些信号可以用不同的方式来区分雨雪，并提供有关冰相降水颗粒的形状、雨中液滴大小分布以及这些量随高度和时间变化的信息。这类测量将对降水的形成和演变提供新的见解，从根本上促进云物理，并提供改善中尺度和气候模式中降水处理所需的信息。

This is a Major Research Instrumentation award that supports the development of a portable, three-wavelength scanning radar designed for meteorological research. Called the Advanced Multi-Frequency Radar (AMFR), it consists of a single antenna capable of transmitting and receiving frequencies in the Ku-band (13 GHZ), Ka-band (33 GHz), and W-band (95 GHz). (These frequencies correspond respectively to wavelengths of 2.2, 0.91, and 0.32 cm.) Each of the three radar systems will be capable of both Doppler and polarization measurements. The PI has already developed a dual-wavelength radar called the Cloud Profiling Radar System (CPRS), which operates at 0.9 and 0.3 cm. This award enables the addition of the third radar having 2.2 cm wavelength, the construction of a new antenna, and improvement of the sensitivity of the existing systems at 0.9 and 0.3 cm. A unique feature of the radar is a system of feeds designed to insure that the single antenna produces collocated, matched beams for the three wavelengths. Measurements at all wavelengths will thus be from the same volume of cloud. The AMFR will be highly portable and relatively inexpensive to deploy. Applications will be primarily to cloud microphysics. Initial emphasis will be on layer clouds and precipitation processes in winter storms. The radar will be able to detect some precipitation-free clouds, at least at the shorter wavelengths. Moreover, rain and snow, when present, give different signals at the three receivers because the polarization characteristics of precipitation and the deviations from Rayleigh scattering both depend on wavelength. These signals can be employed in various ways to distinguish rain from snow and to give information on the shape of ice-phase precipitation particles, the drop-size distribution in rain, and the variation of these quantities with height and time. Measurements of this kind will give new insight on the formation and evolution of precipitation, contributing fundamentally to cloud physics and providing information needed to improve the treatment of precipitation in mesoscale and climate models.