CoAuthors

Michel Tsamados (University College London, United Kingdom); Stroeve Julienne (University College London, United Kingdom); Alan Muir (University College London, United Kingdom); Thomas Armitage (JPL, USA); Pierre Féménias (ESA, Italy)

Sentinel-3B was launched by the European Space Agency in April 2018, joining Sentinel-3A (launched February 2016) in a mission devoted to long-term operational measurements of global surface topography. The two-satellite constellation (from the Copernicus Programme) provides optimum global coverage and short revisit times (less than two days) at the equator. The Sentinel-3 satellites are equipped with SRAL, a dual-frequency Ku / C band SAR altimeter, allowing surface elevation retrievals up to 81.5º latitude. By measuring the elevation difference between the ocean surface in leads and sea ice floes, sea ice freeboard can be retrieved, and in turn sea ice thickness and volume can be calculated. ESA’s CryoSat-2 satellite, which has been successfully providing sea ice thickness estimates since 2010, is now nearly 5 years beyond its planned mission duration. Provided sea ice thickness results from Sentinel-3 are shown to be consistent with CryoSat-2, the mission ensures the continuation of the Arctic sea ice thickness record (up to 81.5º latitude) for the next 7-12 years. Furthermore, consistency between measurements permits the combination of observations from the three satellites, offering an unprecedented opportunity for high temporal/spatial resolution observations of Arctic sea ice from radar altimetry.

Here, we show the current performance of the Sentinel-3 L2 products over sea ice from the S3 Mission Performance Centre analysis and demonstrate how further improvements in sea ice freeboard measurement can be achieved by optimised CPOM sea ice processing similar to that employed for CryoSat-2. We show that the optimised results are consistent across the period of overlap between CryoSat-2 and the Sentinel-3 satellites. Sentinel-3B is now operational in the same orbit as Sentinel-3A but with a phase difference of 140º. We quantify the increase in spatial and temporal resolution afforded by the combination of CryoSat-2, Sentinel-3A, and -3B and showcase some 10-day time series of Arctic sea ice thickness in the Beaufort and Greenland seas.