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| Titel |
The Meridional Overturning Circulation and the Subpolar Gyre observed at the A25-OVIDE section in June 2002 and 2004 |
| VerfasserIn |
P. Lherminier, H. Mercier, T. Huck, C. Gourcuff, F. F. Pérez, P. Morin, C. Kermabon |
| 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 |
250024664
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| Zusammenfassung |
| The nature of the relation between the Subpolar Gyre full-depth circulation and the variability
of the Meridional Overturning Cell will be addressed here by comparing two snapshots of the
North Atlantic as delivered by two Greenland-Portugal hydrographic sections. The
corresponding cruises were carried out in June-July 2002 and June-July 2004 on R/V
Thalassa in the frame of the Ovide project. The absolute transports across the Ovide
lines were estimated using a box inverse model constrained by the direct acoustic
Doppler current profiler velocity measurements and by an overall mass balance
across the section. Results of 2004 are presented, and then compared with 2002
transports. Although the main currents were significantly stronger in 2004, the
Meridional Overturning Circulation, driven by the volume balance between the
northward North Atlantic Current and the southward Western Boundary Current, did not
change. The reason was found in a 6 Sv increase in the circulation of the first 1500
meters in the Subpolar Gyre, affecting mainly the circulation of the Western North
Atlantic Central Water and the upper Labrador Sea Water, mostly in the lower limb of
the MOC when calculated in density layers. A warm and salty water mass was
advected into the Iceland Basin via the North Atlantic Current and recirculated into
the Irminger Sea via the Irminger Current, changing the transport profile and the
properties of Western Boundary Current. It was most likely advected into the Labrador
Sea later on. Below, the Deep Western Boundary Current showed remarkably well
mixed water masses in 2004, with a fresher Denmark Strait Overflow Water than in
2002. |
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