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Abstract:
Polar oceans have generally been harder to determine from satellite altimetry because the regions outside the 66 parallel has traditionally only been surveyed satellites in sun-sun-synchronous orbits. With Cryosat-2 this has changed. However, the satellite poses a number of challenges to tidal analysis because of its long ground-track repeat period (368 days) and its diverse measurement modes, low-rate mode (LRM) over the ocean and synthetic aperture radar interferometric mode (SARin) over ice surfaces and parts of the ocean.
The SAMOSA+ physical retracker was developed to process the Cryosat-2 data across measurement modes and hereby enables the determination of the sea state bias. This way it provides more stable sea level estimates compared with traditional empirical retrackers used in the Polar Ocean. Nearly 10 years of Cryosat-2 data have been analyzed for residual ocean tides to the FES2014 ocean tide model in the Arctic Ocean and Antarctic Ocean using the response formalism. We use data from the near monthly repeat pattern of C2 as this has a favorable alias period for most major constituents. Using this information, the long wavelength corrections to the major astronomical constituents M2, S2, K2, N2, K1, O1, P1, and Q1 tides have been mapped for both the ocean and floating ice shelves domains. In addition, several smaller third, fourth and sixth diurnal tides have been determined. Some of these small compound/over tides does show small but consistent signal across regions like the Weddell sea (South Atlantic) and in the Baffin Bay between Greenland and Canada.
