Long-term climatology of vertical profiles of polarimetric variables and ice-microphysical retrievals at X-band – Part 1:  Radar calibration

Scharbach, Tobias; Pejcic, Velibor; Trömel, Silke

doi:10.5194/amt-19-6209-2026

Articles | Volume 19, issue 19

https://doi.org/10.5194/amt-19-6209-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Fusion of radar polarimetry and numerical atmospheric modelling...

https://doi.org/10.5194/amt-19-6209-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 19

Research article

|

02 Oct 2026

Research article |

| 02 Oct 2026

Long-term climatology of vertical profiles of polarimetric variables and ice-microphysical retrievals at X-band – Part 1: Radar calibration

Tobias Scharbach, Velibor Pejcic, and Silke Trömel

Data sets

Polarimetric X-band radar (BoXPol) data monitored in Bonn, Germany, since 2009 to 2023 Silke Trömel, Kai Mühlbauer, Martin Lennefer, Clemens Simmer https://doi.org/10.60507/FK2/D0NVG5

ERA5 reanalysis data interpolated to the 18° QVPs generated with the X-band radar in Bonn (BoXPol) Tobias Scharbach https://doi.org/10.5281/ZENODO.20799703

Python jupyter notebooks for calibration of ZH/ZDR and provided offset values, related to the study: ``Long-term climatology of vertical profiles of polarimetric variables and ice-microphysical retrievals at X-band. Part 1: Radar calibration'' Tobias Scharbach https://doi.org/10.5281/zenodo.20796890

Model code and software

T-matrix calculations for rain Jacob Carlin, Tobias Scharbach, Ju-Yu Chen https://doi.org/10.5281/ZENODO.20829591

Python jupyter notebooks for calibration of ZH/ZDR and provided offset values, related to the study: ``Long-term climatology of vertical profiles of polarimetric variables and ice-microphysical retrievals at X-band. Part 1: Radar calibration'' Tobias Scharbach https://doi.org/10.5281/zenodo.20796890

ERA5 hourly data on pressure levels from 1940 to present H. Hersbach, B. Bell, P. Berrisford, et al. https://doi.org/10.24381/cds.bd0915c6

Short summary

For the X-band radar in Bonn, the birdbath method has proven to be insufficient for calibrating differential reflectivity. This study raises awareness of the need for critically applying the birdbath method. A novel technique for calibrating the reflectivity factor is presented and compared with satellite measurements, serving as ground truth, and a known standard calibration method. The offset values agree well with the satellite and even exceed the accuracy of the standard calibration method.