Project Details
Projekt
A Low-cost Mechanically-Steered Phased-Array Polarimetric Doppler Weather Radar, Phase 2
Applicant
Dr. Stefano Turso
Subject Area
Atmospheric Science
Term
since 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 408027138
Within the project "Low-cost Mechanically-Steered Phased-Array Polarimetric Doppler Weather Radar", develops Fraunhofer FHR in cooperation with the Institute for Geosciences, Department of Meteorology of the University Bonn (UBonn) a Phased-Array Radar (PAR) prototype based on an Active Electronically Scanned Array (AESA) antenna aperture with the final goal of servicing up to one volumetric weather map per minute.A PAR weather radar is optimally suited to improve temporal resolution via instantaneous beam steering. However, wide adoption of such technology has been so far constrained by an inherent increase of cost to actually achieve the same performance of reflector-based solutions.Within Phase I, a unique antenna solution is investigated to effectively decouple beam steering and gain generation, thus yielding minimization of complexity and cost. Instead of directly using an AESA aperture to achieve both beam steering and gain generation, a parabolic cylinder realizes beam focusing in azimuth while a compact PAR positioned in its focal line provides electronic steering as well as focusing in elevation. To support generation of high-quality polarimetric moments, a specialized active antenna excitation technique has been validated to reach more than 40 dB integral cross-polarization discrimination at broadside and above 30 dB at 45° beam tilt.In Phase II, implementation of beam steering is proposed for finalization and operational assessment of the forerunner prototype. Moreover, investigation of beam acceleration techniques is proposed for timely generation of volumetric weather maps, as simplistic reduction of dwell time would lead to larger statistical uncertainties on the polarimetric moments. Implementation of Beam Multiplexing (BMX) is proposed, a technique consisting of sequential transmission of pulse pairs along different directions in order to increase the decorrelation of samples and achieve faster scans without compromising data quality. Furthermore, traditional step-scan scanning is proposed to adaptively complement BMX for the lower elevations depending on the specific weather event statistics with the goal of achieving shortened volumetric scan time without reduction of data quality. Careful realization of such adaptive scanning will be instrumental to fully exploit the scan speed-up potential of PARs and achieve automated prioritized tracking of potentially harmful events.The partner at UBonn will exploit the measurements of available overlapping X-band research radars for an in-depth evaluation of the new PAR and its polarimetric capabilities. Furthermore, the new technology enables to monitor the pre-convective environment with higher temporal resolution, which again improves the capabilities to derive water vapor fields from radar-detected changes in refractive index. We will assess the new capabilities and thus contribute to the fifth objective of the SPP, i.e. radar-based detection of the initiation of convection.
DFG Programme
Priority Programmes
Co-Investigator
Dr.-Ing. Thomas Bertuch
