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Fast Calibration of Weather Radar Systems for Multi Polarization Radar Measurements

Reimann, Jens and Hagen, Martin (2011) Fast Calibration of Weather Radar Systems for Multi Polarization Radar Measurements. 35th Conference on Radar Meteorology, 26-30 September 2011, Pittsburgh, PA, USA.

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Abstract

Polarimetric weather radars, which are now becoming operational, are using a very limited method to retrieve the polarimetric products, called the STAR mode. It uses robust and low cost hardware but cannot measure the full scattering matrix. The Germany Aerospace Center (DLR) in Oberpfaffenhofen, Germany operates a research weather radar for 25 years now with can receive and transmit arbitrary polarizations for each radar pulse to gather the full scattering matrix. The latest development on that radar makes it possible to perform multi polarization measurements. This also enables the radar to estimate weather targets properties using different polarimetric measurement schemes simultaneously within one scan and without any time lag. By this, a direct comparison of different measurement schemes become possible and a characterization of systematic estimation offsets can be performed. Furthermore system effects which influence the polarization, like additional phase shifts on transmit in the STAR mode, can be introduced and studied. The full power of the system can be used by scanning with several polarizations like horizontal/vertical, left/right hand circular and 45/135 degree linear polarization to estimate precipitation parameters. Besides using the optimal combination to polarization pairs for the retrieval of precipitation properties, faster and better scans become possible by using the polarimetric decorrelation to get more independent samples from the target. All these measurements have to be combined with new calibration efforts on the radar to make meaningful measurements. An end to end calibration of weather radar is always very challenging. As the used radar is not reciprocal and different polarizations are to be calibrated, a completely new calibration system, called polarimetric active radar calibrator (PARC), was designed and build. It is made to measure the polarization purity at least down to -35dB. It can handle the non reciprocal behavior of the radar and is fast enough to measure every single radar pulse transmitted. The measurements are performed in the far field of the radar antenna. Therefore the PARC system can be remotely controlled by the radar. This makes a self calibration of the radar feasible. Due to its modular concept the PARC can be easily adapted to other radars as well.

Document Type:Conference or Workshop Item (Speech)
Title:Fast Calibration of Weather Radar Systems for Multi Polarization Radar Measurements
Authors:
AuthorsInstitution or Email of Authors
Reimann, JensJens.Reimann@dlr.de
Hagen, MartinMartin.Hagen@dlr.de
Date:29 September 2011
Keywords:Radar, Weather Radar, Calibration, Polarization, Polarisation, Multi Polarization Measurement
Event Title:35th Conference on Radar Meteorology
Event Location:Pittsburgh, PA, USA
Event Type:international Conference
Event Dates:26-30 September 2011
Organizer:American Meteorological Society
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:ATM and Operation
DLR - Research area:Aeronautics
DLR - Program:L AO - Air Traffic Management and Operation
DLR - Research theme (Project):L - Climate, Weather and Environment
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Cloud Physics and Traffic Meteorology
Deposited By: Jens Reimann
Deposited On:29 Dec 2011 14:29
Last Modified:29 Dec 2011 14:29

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