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| Titel |
On the role of mesoscale eddies in the ventilation of Antarctic Intermediate Water |
| VerfasserIn |
Z. Lachkar, J.-C. Orr, J.-C. Dutay, P. Delecluse |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250027631
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| Zusammenfassung |
| The spatial distribution of Antarctic Intermediate Water (AAIW) formation and ventilation
remains a matter of debate. Some studies suggest that AAIW forms nearly homogeneously in
a circumpolar pattern, whereas others favor more localized formation particularly in the
southeast Pacific Ocean. We show here that the patterns and magnitude of AAIW formation
and ventilation are substantially affected by mesoscale eddies. To diagnose the role of eddies,
we made global CFC-11 simulations in two versions of the ocean general circulation model
OPA9, a "non-eddying", coarse-resolution version (2-cosφà 2-, ORCA2) and an "eddying"
or eddy-permitting version (1
2-cosφÃ1
2-, ORCA05). In the noneddying simulation, AAIW
subducts in a near homogeneous, circumpolar pattern; in the eddying simulation, the
distribution of AAIW ventilation is patchier. Increasing resolution causes the AAIW
layer to thin by 32% on average in the Indian sector, but only by 11% in the Pacific
sector. This patchiness appears due to the zonal wind stress, which is weak over
much of the Pacific and southwest Atlantic sectors but is strong over the Indian
sector. Consequently, the effect of eddies is largest in the Indian Ocean, moderate in
the Atlantic, and smallest in the Pacific basin. Although the Gent & McWilliams
(GM) eddy parameterization improves the overall vertical structure of density in the
Southern Ocean, applying it in our non-eddying model still results in the nearly
uniform circumpolar distribution of AAIW ventilation, in contrast to the observations. |
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