Cloud Radar calibration transfer campaign in Jülich

With the objective of testing the calibration transfer service of CCRES, the CCRES-FR reference cloud radar (94 GHz BASTA) was operated at the JOYCE observatory in Jülich, Germany, next to the local MIRA 35 GHz radar for 3 months (December 2023 - February 2024). Both radars sampled a large number of cloud profiles are used  to transfer the reference calibration to the local radar.

Results indicate that the JOYCE radar has a mean bias of 0.2 dB with respect to the reference radar, which is negligible when compared with the calibration transfer uncertainty (0.9 dB). The obtained parameters have enabled the writing of an official calibration report, and a reflection on how to implement re-calibrations within CloudNET products.

The result has also been validated by calibrating the reference radar before and after the campaign, where a difference of about 0.2 dB has been found, again well under the experiment uncertainty of 0.8 dB. This enables us to affirm that the reference radar calibration did not change meaningfully during its displacement to Germany.

Information about the procedure and the time and personnel resources needed were shared during the CCRES workshop of the 11th of June 2024. This information will also be useful for a cost-benefit evaluation of calibration transfer as a service.