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www.ocean-sci-discuss.net/6/1513/2009/
doi:10.5194/osd-6-1513-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Impact of model resolution on sea-level variability characteristics at various space and time scales: insights from four DRAKKAR global simulations and the AVISO altimeter data
1Laboratoire des Ecoulements Géophysiques et Industriels, Grenoble, France
2Dept. of Oceanography, Florida State University, USA
3National Oceanography Centre, Southampton, UK
4Laboratoire de Physique des Océans, Brest, France
*now at: Department of Meteorology, Stockholm University, Sweden
**now at: Northwest Atlantic Fisheries Centre, Fisheries and Ocean Canada, Canada
Abstract. Four global ocean/sea-ice simulations driven by the same realistic 46-year daily atmospheric forcing were performed within the DRAKKAR project at 2°, 1°, ½° and ¼° resolutions. Model sea-level anomalies are collocated over the period 1993–2004 onto the AVISO SLA dataset. These five collocated SLA datasets are then filtered and quantitatively compared over various time and space scales regarding three characteristics: SLA standard deviations, spatial correlations between SLA variability maps, and temporal correlations between observed and simulated band-passed filtered local SLA timeseries. Beyond the 2°–1° transition whose benefits are quite moderate, further increases in resolution and associated changes in subgrid scale parameterizations simultaneously induce (i) strong increases in SLA standard deviations, (ii) strong improvements in the spatial distribution of SLA variability, and (iii) slight decreases in temporal correlations between observed and simulation SLA timeseries. These 3 effects are not only clear on mesoscale (14–180 days) and quasi-annual (5–18 months) fluctuations, but also on the slower (interannual), large-scale variability ultimately involved in ocean-atmosphere coupled processes. Most SLA characteristics are monotonically affected by successive resolution increases, but irregularly and with a strong dependance on frequency and latitude. Benefits of enhanced resolution are maximum in the ½°–¼° transition, in the 14–180 day range, and within eddy-active mid- and high-latitude regions. They are particularly clear in the Southern Ocean where mesoscale eddies probably sustain a substantial intrinsic interannual variability.
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Citation: Penduff, T., Juza, M., Brodeau, L., Smith, G. C., Barnier, B., Molines, J.-M., and Treguier, A.-M.: Impact of model resolution on sea-level variability characteristics at various space and time scales: insights from four DRAKKAR global simulations and the AVISO altimeter data, Ocean Sci. Discuss., 6, 1513-1545, doi:10.5194/osd-6-1513-2009, 2009. Bibtex EndNote Reference Manager XML
