View of Montsec Observatory © isardSAT

After nearly four years in operation, the calibration site at Montsec Observatory has proven its ability to deliver long-term calibration measurements for the Sentinel-6 satellites with excellent results (F. Gibert et al., 2024). Furthermore, it has incorporated data from other radar altimeters, including CryoSat-2 since 2022, and Sentinel-3B since 2023, both achieving similar results to Sentinel-6.

As the prominence of the site ensures low background signals (or clutter) to the corner reflector’s measurements, the site has become a crucial benchmark to test new calibration procedures and to investigate the residual noise sources that contribute to the actual radar altimeter’s sensitivity.

For instance, the current data series allows to monitor the power decay of the satellite due to system aging, or to set upper limits to the overall drifts observed, among others; topics being of high interest for the design of new generation of altimeters, and the geodesic and climate change communities.