Steric sea level variability (1993-2010) in an ensemble of ocean reanalyses and objective analyses

• Published in: Climate Dynamics
• Main Authors: Storto, Andrea, Masina, Simona, Balmaseda, Magdalena, Guinehut, Stéphanie, Xue, Yan, Szekely, Tanguy, Fukumori, Ichiro, Forget, Gael, Chang, You-Soon, Good, Simon A., Köhl, Armin, Vernieres, Guillaume, Ferry, Nicolas, Peterson, K. Andrew, Behringer, David, Ishii, Masayoshi, Masuda, Shuhei, Fujii, Yosuke, Toyoda, Takahiro, Yin, Yonghong, Valdivieso, Maria, Barnier, Bernard, Boyer, Tim, Lee, Tony, Gourrion, Jérome, Wang, Ou, Heimback, Patrick, Rosati, Anthony, Kovach, Robin, Hernandez, Fabrice, Martin, Matthew J., Kamachi, Masafumi, Kuragano, Tsurane, Mogensen, Kristian, Alves, Oscar, Haines, Keith, Wang, Xiaochun
• Other Authors: Collecte Localisation Satellites (CLS), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Écoulements Géophysiques et Industriels Grenoble (LEGI ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: Ocean reanalysis evaluation; Sea level variability; Altimetry; Gravimetry; [SDU]Sciences of the Universe [physics]; Southern Ocean
• Online Access: https://insu.hal.science/insu-03684928; https://insu.hal.science/insu-03684928/document; https://insu.hal.science/insu-03684928/file/storto.pdf; https://doi.org/10.1007/s00382-015-2554-9

International audience Quantifying the effect of the seawater density changes on sea level variability is of crucial importance for climate change studies, as the sea level cumulative rise can be regarded as both an important climate change indicator and a possible danger for human activities in coastal areas. In this work, as part of the Ocean Reanalysis Intercomparison Project, the global and regional steric sea level changes are estimated and compared from an ensemble of 16 ocean reanalyses and 4 objective analyses. These estimates are initially compared with a satellite-derived (altimetry minus gravimetry) dataset for a short period (2003-2010). The ensemble mean exhibits a significant high correlation at both global and regional scale, and the ensemble of ocean reanalyses outperforms that of objective analyses, in particular in the Southern Ocean. The reanalysis ensemble mean thus represents a valuable tool for further analyses, although large uncertainties remain for the inter-annual trends. Within the extended intercomparison period that spans the altimetry era (1993-2010), we find that the ensemble of reanalyses and objective analyses are in good agreement, and both detect a trend of the global steric sea level of 1.0 and 1.1 ± 0.05 mm/year, respectively. However, the spread among the products of the halosteric component trend exceeds the mean trend itself, questioning the reliability of its estimate. This is related to the scarcity of salinity observations before the Argo era. Furthermore, the impact of deep ocean layers is non-negligible on the steric sea level variability (22 and 12 % for the layers below 700 and 1500 m of depth, respectively), although the small deep ocean trends are not significant with respect to the products spread.