THE CRYORAD AIRBORNE BAFFIN BAY CAMPAIGN: FIRST RESULTS AND LESSON LEARNED

M. Brogioni¹, F. Montomoli¹, M. Leduc-Leballeur¹, G. Macelloni¹, J. Boutin², J. Johnson³, T.Casal⁴, M. Drusch⁴

¹CNR-IFAC, ²CNRS-IPSL, ³The Ohio State University, ⁴ESA-ESTEC

Over the past decade, airborne surveys conducted in Greenland and Antarctica have demonstrated the potential of low-frequency wideband radiometers in monitoring polar regions, offering unprecedented capabilities compared to spaceborne satellites using the 1400-1427 MHz portion of the spectrum. The ESA Earth Explorer 12 CryoRad mission candidate aims to fully demonstrate these capabilities and produce key scientific data for advancing cryosphere studies. The three main mission objectives are: (i) Better assess the mass balance and stability of ice sheets, by bridging the observation gap for ice sheet temperature profiles of Antarctic and Greenland ice sheets that extend from surface to base (a dataset previously available only through limited borehole observations or models); (ii) Better assess the freshwater cycle and water mass formation at high latitudes, by reducing the uncertainty in cold water sea surface salinity measurements by at least a factor of 2 compared with existing L-band measurements; (iii) Investigate sea ice dynamics and salinity exchange processes in the Arctic and Antarctic by improving sea ice thickness estimates for sea ice in the 0.5-1 m thickness range and delivering the first spaceborne observations of sea ice salinity.

In order to advance CryoRad’s progress, ESA funded dedicated experimental activities for investigating key components of the mission. These activities include detailed assessment of the dielectric permittivity of ice at low frequencies and temperatures and the collection of experimental data. The August 2025 Baffin Bay campaign contributes to the latter goal. The campaign’s objective was to test the CNR-IFAC LoMiRad radiometer onboard a Basler aircraft in real world conditions, to assess its performance, and to collect ultra-wideband brightness temperature data over open water. The results provide the mission with multiple benefits: an operational airborne demonstrator, investigations of spectrum occupancy in polar and near-polar regions, and the collection of experimental data over open sea (a target that to date has seen only limited measurement with ultrawideband radiometry). Campaign flight routes were designed to follow the 2025 Amundsen expedition, a Canadian scientific cruise that collects many sea water geophysical parameters including sea surface salinity and temperature (https://amundsenscience.com/discover-expeditions/). Additional flight routes intersected with an Ungava Bay oceanographic campaign of the Université du Quebec-Trois Rivieres.

The Baffin Bay campaign took place 11 August – 4 September. The LoMiRad scientific team of Marco Brogioni, Marion Leduc-Leballeur and Francesco Montomoli was supported by the logistic team from Kenn Borek Air. A first campaign phase in Calgary, AB installed the instrument on the aircraft and performed ground tests using terminations kept at ambient temperature and dipped in liquid nitrogen. Pt100 probes and inclinometer sensors were tested along with IR and visible cameras. After certification an authorization by Transport Canada the second campaign phase was conducted 18-28 August. Data collection was carried out over Baffin Bay and during transit to/from the area. In total, eight scientific flights took place over the south part of Baffin Bay, Davis Strait, Ungava Bay, Penny Ice Cap, north Baffin Bay, and Barnes Ice Cap. Overall approximately 70 hours of flight data were collected for the flight routes available at https://www.cryorad.eu/CryoSSSS_GIS/

The datasets are presently undergoing processing and calibration. Results will be shown at the meeting, along with information on spectrum occupancy over specific sites and lessons learned during the certification and scientific campaign.