Preprints
https://doi.org/10.5194/amt-2021-194
https://doi.org/10.5194/amt-2021-194

  06 Jul 2021

06 Jul 2021

Review status: this preprint is currently under review for the journal AMT.

Calibration of radar differential reflectivity using quasi-vertical profiles

Daniel Sanchez-Rivas and Miguel A. Rico-Ramirez Daniel Sanchez-Rivas and Miguel A. Rico-Ramirez
  • Department of Civil Engineering, University of Bristol, Bristol, BS8 1TR, United Kingdom

Abstract. The differential reflectivity (ZDR) is a crucial weather radar measurement that helps to improve quantitative precipitation estimates using polarimetric weather radars. However, a system bias between the horizontal and vertical channels generated by the radar produces an offset in ZDR. Existing methods to calibrate ZDR measurements rely on vertical observations of ZDR taken in rain, in which ZDR values close to 0 dB are expected. However, not all weather radar systems are capable of producing vertical pointing measurements. In this work, we present and analyse a novel method for correcting and monitoring the ZDR offset using quasi-vertical profiles of polarimetric variables. The method is applied to radar data collected through one year of precipitation events by two operational C-band weather radars in the UK. The proposed method proves effective in achieving the required accuracy of 0.1 dB for the calibration of ZDR as the calibration results are consistent with the traditional method based on vertical profiles. Additionally, the method is independently evaluated using disdrometers located near the radar sites. The results showed a good agreement between disdrometer-derived and radar-calibrated ZDR measurements.

Daniel Sanchez-Rivas and Miguel A. Rico-Ramirez

Status: open (until 31 Aug 2021)

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Daniel Sanchez-Rivas and Miguel A. Rico-Ramirez

Daniel Sanchez-Rivas and Miguel A. Rico-Ramirez

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Short summary
In this work, we examine different methods for monitoring the calibration of the radar differential reflectivity ZDR. First, we implemented a well-known procedure to calibrate and monitor the ZDR offset using vertical profiles of polarimetric variables. Then, we propose a novel, operational method to calibrate ZDR using quasi-vertical profiles of polarimetric variables. We observed an excellent agreement between both methods, as the errors (MAE and RMSE) are within 0.1 dB.