Update on CryoSat-2 long-term ocean data analysis and validation

• Main Authors: Naeije, M.C. (author), Schrama, Ernst (author), Di Bella, Alessandro (author), Bouffard, Jerome (author)
• Format: Still Image
• Language: English
• Published: 2022
• Subjects: Greenland; Antarc*; Antarctica; Sea ice
• Online Access: http://resolver.tudelft.nl/uuid:c3389792-7f1f-405b-8ad0-706918ffc5ae; https://doi.org/10.24400/527896/a03-2022.3316

ESA’s Earth Explorer CryoSat-2 precisely measures the changes in the thickness of marine ice floating on the polar oceans and variations in the thickness of the vast ice sheets that overlie Greenland and Antarctica. The data delivered by the CryoSat-2 mission completes the picture to determine and understand the ice role in the Earth system in general and climate change in particular. For this, the quality of the satellite orbit, the measurements of the altimeter, and all required corrections have to meet the highest performance; not only over the ice caps and sea-ice surface but also over the oceans. As Cryosat-2 ocean products continuously evolve they need to be quality controlled and thoroughly validated via science-oriented diagnostics based on multi-platform in situ data, models and other (altimeter) satellite missions. The rationale for this is based on the new CryoSat-2 scientific roadmap, which specifically addresses the key technical and scientific challenges related to the long-term monitoring of sea-level and ocean circulation changes in the context of Global Warming. This also involves opportunities for synergy with missions like ICESAT-2 and the upcoming Copernicus CRISTAL mission. In this context, the objective of our research is the long-term monitoring of the level-2 CryoSat-2 Geophysical Ocean Product (GOP), by evaluating the stability of the measurement system and identifying potential biases, trends and drifts over the ocean, through calibration and comparisons with concurrent ocean altimeter data, supported by the Radar Altimeter Database System (RADS). Independently, we also address this by comparing the GOP geophysical parameters with external models and in situ measurements such as the ones from selected sets of tide gauges. The very precise determination of the orbital height is part of the research activity but dealt with in a separate paper. For our activity we persistently monitor, analyze and identify systematic errors in the observations, estimated (trends in) biases in range, ...