CryoSat Ice Baseline-D validation and evolutions

• Published in: The Cryosphere
• Main Authors: Meloni, Marco, Bouffard, Jerome, Parrinello, Tommaso, Dawson, Geoffrey, Garnier, Florent, Helm, Veit, Di Bella, Alessandro, Hendricks, Stefan, Ricker, Robert, Webb, Erica, Wright, Ben, Nielsen, Karina, Lee, Sanggyun, Passaro, Marcello, Scagliola, Michele, Simonsen, Sebastian Bjerregaard, Sandberg Sørensen, Louise, Brockley, David, Baker, Steven, Fleury, Sara, Bamber, Jonathan, Maestri, Luca, Skourup, Henriette, Forsberg, René, Mizzi, Loretta
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Copernicus 2020
• Subjects: Austfonna; Ice cap; Sea ice; The Cryosphere
• Online Access: https://epic.awi.de/id/eprint/52608/; https://epic.awi.de/id/eprint/52608/1/tc-14-1889-2020.pdf; https://hdl.handle.net/10013/epic.17ae3518-4f03-485c-b4d7-506ab900a023

The ESA Earth Explorer CryoSat-2 was launched on 8 April 2010 to monitor the precise changes in the thickness of terrestrial ice sheets and marine floating ice. To do that, CryoSat orbits the planet at an altitude of around 720 km with a retrograde orbit inclination of 92∘ and a quasi repeat cycle of 369 d (30 d subcycle). To reach the mission goals, the CryoSat products have to meet the highest quality standards to date, achieved through continual improvements of the operational processing chains. The new CryoSat Ice Baseline-D, in operation since 27 May 2019, represents a major processor upgrade with respect to the previous Ice Baseline-C. Over land ice the new Baseline-D provides better results with respect to the previous baseline when comparing the data to a reference elevation model over the Austfonna ice cap region, improving the ascending and descending crossover statistics from 1.9 to 0.1 m. The improved processing of the star tracker measurements implemented in Baseline-D has led to a reduction in the standard deviation of the point-to-point comparison with the previous star tracker processing method implemented in Baseline-C from 3.8 to 3.7 m. Over sea ice, Baseline-D improves the quality of the retrieved heights inside and at the boundaries of the synthetic aperture radar interferometric (SARIn or SIN) acquisition mask, removing the negative freeboard pattern which is beneficial not only for freeboard retrieval but also for any application that exploits the phase information from SARIn Level 1B (L1B) products. In addition, scatter comparisons with the Beaufort Gyre Exploration Project (BGEP; https://www.whoi.edu/beaufortgyre, last access: October 2019) and Operation IceBridge (OIB; Kurtz et al., 2013) in situ measurements confirm the improvements in the Baseline-D freeboard product quality. Relative to OIB, the Baseline-D freeboard mean bias is reduced by about 8 cm, which roughly corresponds to a 60 % decrease with respect to Baseline-C. The BGEP data indicate a similar tendency with a mean draft ...