Properties of Arctic mixed-phase clouds explored by multi-frequency radars

Arctic mixed-phase low-level clouds pose a large challenge to weather and climate models. The new G-band radar GRaWAC (G-band Radar Water vapor profiling and Arctic Clouds) is a frequency-modulated continuous wave radar with two frequencies at 167.3 and 174.8 GHz. Measurements at higher frequencies than conventional cloud radars and near the 183 GHz water vapor absorption line enable for extracting water vapor profiles in clouds by making use of the differential absorption technique for measurements at the two frequencies. In combination with radar measurements in the W-band, the high frequencies also make the observations of small hydrometeors in the non-Rayleigh regime possible, enabling future retrievals of hydrometeor phase and size distribution based on differential radar measurements.

We present observations from the ship-based campaign VAMPIRE that took place from August to October 2024 in the Central Arctic Ocean on the research vessel Polarstern and from a ground-based intensive operation period from January to March 2025 at AWIPEV station in Ny-Ålesund, Svalbard. The G-band radar GRaWAC alongside a W-band radar measured in both campaigns, while the observations at AWIPEV were expanded by including a Ka-band radar. First results show the presence of mixed-phase clouds which will be evaluated in their respective environmental conditions, determined by wind and precipitation measurements, and 6- to 12-hourly radiosondes. The contribution will present the post-processed radar data of both intensive measurement periods, including attenuation and ship motion correction, and first analyses of microphysical properties in mixed-phase clouds and water vapor profiles.