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| Titel |
Cold climate westerly winds over the Southern Ocean |
| VerfasserIn |
L. Sime, C. Le Quere, E. Wolff, W. Connolley, A. De Boer, L. Bopp |
| 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 |
250021113
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| Zusammenfassung |
| Many elements of the ocean circulation depend on the Southern Ocean wind field, however
Quaternary cool climate westerlies are poorly understood. We use an atmospheric general
circulation model HadAM3 to simulate wind changes over a large variety of cool
climates.
We show that extra-tropical latitudes which experience the most intense sea surface
temperature (SST) cooling anomalies show the largest changes in the westerlies, mainly in
the winter season. New sea ice, formed under the cooler conditions, slows the surface
westerlies winds by up to 2.8 ms-1 in winter. Together SST and sea ice affects produce
complex bimodal change patterns. The seasonally dependent response to changes in
sea ice and SST, plus the inability of simple wind statistic to convey the changes,
explain the disagreements found between previous observations and modelling
studies.
In general the wind maximum tends to increase and move north with the hemispheric
meridional temperature gradient. Tropical temperature reductions strongly affect the
wavenumber-3 southern hemisphere pattern producing differing responses across different
sectors of the southern ocean, again dominated by wintertime changes. However, the total
mean Southern Ocean shear stress (which may drive the ACC) depends strongly
on the hemispheric temperate gradient and is almost independent of experiment
details. |
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