{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:39:21Z","timestamp":1760150361640,"version":"build-2065373602"},"reference-count":42,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2023,11,19]],"date-time":"2023-11-19T00:00:00Z","timestamp":1700352000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"European Space Agency ESRIN EOP-GMQ","award":["4000112740"],"award-info":[{"award-number":["4000112740"]}]},{"name":"TU Delft","award":["4000112740"],"award-info":[{"award-number":["4000112740"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>ESA\u2019s Earth explorer mission CryoSat-2 has an ice-monitoring objective, but it has proven to also be a valuable source of observations for measuring impacts of climate change over oceans. In this paper, we report on our long-term ocean data analysis and validation and give our final words on CryoSat-2\u2019s Geophysical Ocean Products (GOP) Baseline-C. The validation is based on a cross comparison with concurrent altimetry and with in situ tide gauges. The highlights of our findings include GOP Baseline-C showing issues with the ionosphere and pole tide correction. The latter gives rise to an east\u2013west pattern in range bias. Between Synthetic Aperture Radar (SAR) and Low-Resolution Mode (LRM), a 1.4 cm jump in range bias is explained by a 0.5 cm jump in sea state bias, which relates to a significant wave height SAR-LRM jump of 10.5 cm. The remaining 0.9 cm is due to a range bias between ascending and descending passes, exhibiting a clear north\u2013south pattern and ascribed to a timing bias of +0.367 ms, affecting both time-tag and elevation. The overall range bias of GOP Baseline-C is established at \u22122.9 cm, referenced to all calibrated concurrent altimeter missions. The bias drift does not exceed 0.2 mm\/yr, leading to the conclusion that GOP Baseline-C is substantially stable and measures up to the altimeter reference missions. This is confirmed by tide gauge comparison with a selected set of 309 PSMSL tide gauges over 2010\u20132022: we determined a correlation of R = 0.82, a mean standard deviation of \u03c3=5.7 cm (common reference and GIA corrected), and a drift of 0.17 mm\/yr. In conclusion, the quality, continuity, and reference of GOP Baseline-C is exceptionally good and stable over time, and no proof of any deterioration or platform aging has been found. Any improvements for the next CryoSat-2 Baselines could come from sea state bias optimization, ionosphere and pole tide correction improvement, and applying a calibrated value for any timing biases.<\/jats:p>","DOI":"10.3390\/rs15225420","type":"journal-article","created":{"date-parts":[[2023,11,20]],"date-time":"2023-11-20T00:30:50Z","timestamp":1700440250000},"page":"5420","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["CryoSat Long-Term Ocean Data Analysis and Validation: Final Words on GOP Baseline-C"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0164-0507","authenticated-orcid":false,"given":"Marc","family":"Naeije","sequence":"first","affiliation":[{"name":"Department of Space Engineering, FAC Aerospace Engineering, Delft University of Technology (TU Delft), Kluyverweg 1, 2629 HS Delft, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9727-4902","authenticated-orcid":false,"given":"Alessandro","family":"Di Bella","sequence":"additional","affiliation":[{"name":"ESA Centre for Earth Observation ESA\/ESRIN, Largo Galileo Galilei 1, 00044 Frascati, RM, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Teresa","family":"Geminale","sequence":"additional","affiliation":[{"name":"Exprivia S.p.A. Defence & Aerospace Digital Factory, Via della Bufalotta 378, 00139 Roma, RM, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2018-7373","authenticated-orcid":false,"given":"Pieter","family":"Visser","sequence":"additional","affiliation":[{"name":"Department of Space Engineering, FAC Aerospace Engineering, Delft University of Technology (TU Delft), Kluyverweg 1, 2629 HS Delft, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,11,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1046","DOI":"10.1016\/j.asr.2011.07.002","article-title":"A demonstration of the potential of CryoSat-2 to contribute to mesoscale observation","volume":"50","author":"Dibarboure","year":"2012","journal-title":"Adv. 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