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| Titel |
Sea-level expression of intrinsic and forced interannual variabilities: a global OGCM study. |
| VerfasserIn |
Thierry Penduff, Mélanie Juza, Bernard Barnier, Jan Zika, William K. Dewar, Anne-Marie Treguier, Jean-Marc Molines, Nicole Audiffren |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250047705
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| Zusammenfassung |
| This study evaluates in a realistic context the local contributions of direct atmospheric forcing
and intrinsic oceanic processes on interannual sea-level anomalies (SLA). A 1/4- global
ocean/sea-ice general circulation model, driven over 47 years by the full range of atmospheric
timescales, is first shown to reproduce most observed features of the high- and
low-frequency SLA variability from 1993 to 2004. Comparing this simulation with a second
one driven only by the climatological annual cycle reveals that the intrinsic part
of the total interannual SLA variance exceeds 40% over half of the open ocean
area, and exceeds 80% over one fifth of it. This intrinsic contribution is particularly
strong in eddy-active regions (more than 70-80% in the Southern Ocean and western
boundary current extensions) as predicted by idealized studies, as well as within
the 20-30- latitude bands. The atmosphere directly forces most of the interannual
SLA variance at low latitudes and in most mid-latitude eastern basins, in particular
north of about 40-N in the Pacific. The interannual SLA variance is almost entirely
due to intrinsic processes south of the Antarctic Circumpolar Current in the Indian
sector, while half of this variance is forced by the atmosphere north of it. The same
simulations were performed and analyzed at 2- resolution as well: switching to this
laminar regime yields a comparable forced variability (large-scale distribution and
magnitude), but almost suppresses the intrinsic variability. This probably explains
why laminar ocean models largely underestimate the interannual SLA variance. |
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