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| Titel |
Towards the development of a modeling framework for the study of Southern Ocean variability from interannual to multi-decadal time scales |
| VerfasserIn |
Lavinia Patara, Claus Böning, Arne Biastoch, Erik Behrens |
| 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 |
250049468
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| Zusammenfassung |
| The aim of this study is to develop a modeling framework suitable for investigating the
interannual to multi-decadal responses of the Southern Ocean to wind changes. It is in fact
hypothesized that anthropogenic climate change may affect the location and intensity of
mid-latitude westerly winds, thereby influencing the Antarctic Circumpolar Current (ACC)
transport, the meridional overturning circulation, as well as potentially the ocean
CO2 uptake. Recent studies moreover suggest that ocean mesoscale eddies may be
importantly involved in the ACC response to wind changes, owing to their capability
of transporting heat poleward. Ocean general circulation models are a valuable
tool for investigating Southern Ocean variability on decadal and multi-decadal
time scales, yet their applicability is often hindered by spurious model drifts. We
investigate the nature and causes of the model spurious drifts in the Southern Ocean
within the NEMO modeling framework at 1/2Ë and 1/4Ë resolution (ORCA05 and
ORCA025). We diagnose a steady decrease of the ACC transport (0.38 Sv year-1) in the
course of a 130-year climatological simulation and find this drift to be related to
a loss of high-density water masses south of 60Ë S. This bias is hardly solvable
within modeling frameworks at an intermediate resolution, which lack the explicit
representation of small-scale processes leading to bottom water formation close to
the Antarctica coast. We therefore propose to contain the model spurious drift by
applying, south of the ACC, a weak relaxation of deep temperature and salinity to
observed climatologies: we find that the model spurious drift is reduced whilst the
ACC dynamics is left capable to freely evolve. We subsequently show how the
applied deep restoring affects the temporal evolution of the ACC transport and
of the meridional overturning circulation. We finally present how the “corrected”
ORCA05 simulation will be used as a baseline for a high-resolution two-way nesting
approach in the Southern Ocean, discussing possible strategies and related issues. |
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