Regional patterns of observed sea level change: insights from a 1/4° global ocean/sea-ice hindcast |
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| Authors: | Alix Lombard Gilles Garric Thierry Penduff |
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| Institution: | (1) CNES, 18 Avenue Edouard Belin, 31 401 Toulouse Cedex 9, France;(2) MGC/MERCATOR-Ocean, 8–10 rue Hermès, Parc Technologique du Canal, 31520 Ramonville-St-Agne, France;(3) MEOM-LEGI, Laboratoire des Ecoulements Géophysiques et Industriels, CNRS, UJF, INPG, BP53, 38041 Grenoble Cedex 9, France |
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| Abstract: | A global eddy-admitting ocean/sea-ice simulation driven over 1958–2004 by daily atmospheric forcing is used to evaluate spatial
patterns of sea level change between 1993 and 2001. In the present study, no data assimilation is performed. The model is
based on the Nucleus for European Models of the Ocean code at the 1/4° resolution, and the simulation was performed without
data assimilation by the DRAKKAR project. We show that this simulation correctly reproduces the observed regional sea level
trend patterns computed using satellite altimetry data over 1993–2001. Generally, we find that regional sea level change is
best simulated in the tropical band and northern oceans, whereas the Southern Ocean is poorly simulated. We examine the respective
contributions of steric and bottom pressure changes to the total regional sea level changes. For the steric component, we
analyze separately the contributions of temperature and salinity changes as well as upper and lower ocean contributions. Generally,
the model results show that most regional sea level changes arise from temperature changes in the upper 750 m of the ocean.
However, contributions of salinity changes and deep steric changes can be locally important. We also propose a map of ocean
bottom pressure changes. Finally, we assess the robustness of such a model by comparing this simulation with a second simulation
performed by MERCATOR-Ocean based on the same core model, but differing by its short length of integration (1992–2001) and
its surface forcing data set. The long simulation presents better performance over 1993–2001 than the short simulation, especially
in the Southern Ocean where a long adjustment time seems to be needed.
In memory of my little brother Jean-Eudes, whose thirst for science filled out the rich discussions we had about my investigations
and his job as user-service provider for MERCATOR-Ocean. |
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| Keywords: | Regional sea level change Eddy-admitting ocean model Altimetry observations |
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