DURIP: A Dual Frequency Ka-W Band FMCW Scanning Radar for Hydrometeorological Research
Abstract
Millimeter wavelength radars have become an instrument of choice in hydrometeorological research for probing very small atmosphericparticles, as small as 5 to 10 microns. These include nonprecipitating cloud droplets, fog, small ice crystals, supercooled liquid droplets, ice-water mixed phases and scatterers such as small insects and large aerosol particles, especially those undetectable by common weather radars. The most used and beneficial in the millimeter wavelength band are the W-band (frequency ~ 94 GHz, wavelength~ 3.2 mm) and Ka-band (35 GHz, 8.6 mm) radars, also known as cloud radars. They have been used in atmospheric research since the 1980#s, impelled by concerns of the nexus between clouds and Earth#s climate as well as rapid advances in radar technology. Both Ka and W bands have intrinsic merits and disadvantages, but the advent of dual-frequency Ka-W band radars that conjoin Ka and W bands andexploit complementary advantages of both types has had profound implications in remote sensing of hydrometeors. A noteworthy development is the dual-frequency, Ka-W band, FMCW [frequency modulated continuous wave] radars produced by Radiometer-Physics GmbH (RPG) that integrate Ka and W band dual-polarized radars on a common scanning platform. The Ka-W combo operates Ka and W band radars synchronously in time with matched signal (range-bin) settings as a standalone, compact instrument. The unique advantages of such dual-frequency Ka-W band radars include: the ability to detect from very small (~ 5-10 microns) to relatively large (~5 mm) water droplets and ice aggregates (~ 1 cm), enabling the differentiation between regions of ice, cloud droplets, drizzle, mixed-phase hydrometeors and insects; profiling of liquid water content (LWC) and enhanced retrievals of Liquid Water Path (LWP); simultaneous retrieval of binned droplet-size distribution as well as high-resolution air state parameters such as vertical wind and air broadening caused by turbulence and wind shear; retrievals at low beam elevations; and rain profiling capabilities that are untenable by single-frequency cloud radars. In addition, the low weight and small dimensions of FMCW radars compared to magnetron (tube) based alternatives allow deployments on motion-stabilized platforms aboard research vessels.This proposal seeks funding to acquire a dual-frequency, dual polarized, integrated Ka-W band radar system from RPG to support DOD-funded research at University of Notre Dame. Since the Principal Investigator has an RPG FMCW, dual polarized, W-band radar in hand acquired through a FY2019-DURIP grant, funds are requested only topurchase an off-the-shelf Ka-band radar and a scanning platform as well as for system (Ka-W) integration. If successful, the new Ka-W band radar will be immediately deployed in two DOD (ONR) funded projects, one dealing with ice-fog dynamics in the northern slopes of Alaska and the other with lifecycle of the Southeastern Arabian Sea Mini-Warm Pool and monsoon onset, including [moist] deep convection. The latter deployment is coordinated with the Naval Research Laboratories in Monterey, California (MRL-MY) and Stennis, Mississippi, where training of PhD students aboard a research vessel and via exchange visits are planned. A collaborative deployment of new Ka-W band at the NRL-MY Coastal Observation Station is also planned in the backdrop of an extensive suite of hydrometeorological and wind sensors that facilitate instrument intercomparisons and development of radar retrieval methods. Other project proposals are being formulated or submitted for which the Ka-W band will be utilized. The proposed instrument will be used as a graduate-student teaching tool and a shared resources for intra-university collaborative research, and will greatly enhance research infrastructure at University of Notre Dame.Publicly Releasable
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 14, 2024
- Source ID
- N000142512021
Entities
People
- Harindra Fernando
Organizations
- Office of Naval Research
- United States Navy
- University of Notre Dame