P11B.7 Radar calibration using polarimetric observations

Thursday, 9 August 2007
Halls C & D (Cairns Convention Center)
Jonathan J. Gourley, NOAA/NSSL, Norman, OK; and A. J. Illingworth and P. Tabary

While radar polarization diversity has shown improvements in data quality and hydrometeor classification, the accuracy in estimating rainfall remains limited by the calibration of the radar. This study serves as a template to illustrate how differential reflectivity (ZDR) and reflectivity at horizontal polarization (ZH) can be calibrated to within 0.1-0.2 dB and better than 1.0 dB respectively. Hydrometeor observations at vertical incidence are used to calibrate ZDR where the intrinsic values are known to be 0 dB. Calibration of ZH can be achieved using the relationship between ZH, ZDR, and specific differential propagation phase (KDP). KDP is calculated from observations of ZDR and ZH and then integrated in the radial direction to yield a consistency-based differential propagation phase (ΦDP). Differences between consistency and observed ΦDP are attributed to miscalibrated ZH. A dataset comprised of thousands of radial profiles of polarimetric data collected by MeteoFrance's C-band radar near Trappes is used to calibrate ZDR and ZH.
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