Dr. Martin Radenz (Leibniz Institute for Tropospheric Research (TROPOS))
Place: Ludwig-Maximilians-University of Munich (LMU), Germany
Visited Team: Paul Ockenfuß, Prof. Dr. Stefan Kneifel, and Dr. Leonie von Terzi
Time Period: 13.07.2026 – 24.07.2026
Funded by PROM Network Funds


The main objective of the research stay at Ludwig-Maximilians-Universität was to work with Paul Ockenfuß, Dr. Stefan Kneifel, and Dr. Leonie von Terzi on the analysis of cloud radar Doppler spectra, with a particular focus on observations collected at Neumayer Station III in coastal Antarctica. Major focus of the stay was the further development of the peakTree algorithm, including its adaptation to new radar systems, modularization of its interface, and debugging of known issues. The analysis capabilities were further enhanced by experimenting the particle population tracking approach developed by Ockenfuß et al. (2026b). These developments were applied to a case study of snowfall observed at Neumayer Station III, demonstrating the potential of the extended analysis framework (Fig. 1).

A second topic of the stay was the adaptation of the solar-scan method developed by Ockenfuß et al. (2026a) to the RPG FMCW W-band scanning radar. The team also experimented with the possibility of lunar scans to make the pointing correction independent of daytime conditions. As a side result, different RPG FMCW W-band radars were checked for degradation of transmitter power with the result, that 3 out of 5 radars were affected.

The technical developments of peakTree are an important prerequisite for its future adaptation and integration into the ACTRIS-Cloudnet framework. In addition to the joint scientific work, Martin Radenz presented recent research at the MIM Colloquium on 14 July 2026 (seminar title “Observational studies of aerosol effects on mixed-phase clouds above the Southern Ocean and coastal Antarctica”). The presentation provided an opportunity for scientific exchange with researchers at LMU and further discussion of observational studies of Antarctic and Southern Ocean clouds. Overall, the research stay strengthened the collaboration between TROPOS and LMU and resulted in progress in cloud radar Doppler spectra analysis, radar pointing calibration, and the further development of peakTree for broader application within ACTRIS-Cloudnet.

References:

• Ockenfuß, P., G. Köcher, M. Bauer-Pfundstein, and S. Kneifel, 2026a: A Novel Framework for Automatic Scanning Radar Pointing Calibration Using the Sun, Atmos. Meas. Tech., 19, 2961–2984, https://doi.org/10.5194/amt-19-2961-2026.
• Ockenfuß, P., M. Frech, M. Gergely, and S. Kneifel, 2026b: First nationwide analysis of riming using vertical observations from the operational German C-band radar network, Atmos. Meas. Tech., 19, 2125–2147, https://doi.org/10.5194/amt-19-2125-2026.