 |
| Titel |
Irminger Sea as a key site for the Atlantic Meridional Overturning Circulation |
| VerfasserIn |
Artem Sarafanov, Anastasia Falina, Alexey Sokov, Herlé Mercier, Pascale Lherminier, Claire Gourcuff |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250046442
|
|
|
|
|
|
| Zusammenfassung |
| Intense cooling of the upper-ocean waters in the Nordic Seas produces cold dense
overflows to the North Atlantic thereby driving the Atlantic Meridional Overturning
Circulation (MOC) – an important element of the climate system. Observations
and models consistently show that the direct contribution of the Nordic overflows
(~6Â Sv) to the MOC is modest when compared to the MOC strength (~16Â Sv) at the
Subpolar Gyre southern margin and that the exchange across the Greenland-Scotland
Ridge (GSR) is remarkably stable relative to the MOC variability south of the GSR.
Therefore, it is reasonable to expect that the MOC low-frequency variability is
associated for the most part with variability of the light-to-dense water conversion
within the Subpolar Gyre. Localization of the key sites of this conversion is thus
essential.
By combining repeat hydrography (7 annual summer snapshots) with altimetry, we
estimated the 2002–2008 mean absolute transports across the 59.5Ë N transatlantic section
between Cape Farewell (Greenland) and Scotland. The obtained MOCÏă – maximum in
southward transport accumulated from the bottom in density coordinates – is 16.5±2.2Â Sv
(at Ïă0Â =Â 27.55), in agreement with the MOCÏă estimates (16.3±2Â Sv, Ïă0Â -Â 27.55) based
on direct velocity measurements in summer 2002 and 2004 at the OVIDE Cape
Farewell-to-Portugal section. In the next step, we used the obtained mean transports at 59.5Ë
N along with fluxes across the GSR, as available from literature, to estimate the overturning
rate in the GSR–59.5Ë N region by applying a simple box model. The results provide the
following conceptual view of the gyre / overturning circulation at the northern periphery of
the Atlantic Ocean.
The North Atlantic Current / Irminger Current (NAC/IC) carries 21.1±1 Sv of warm
upper-ocean waters across 59.5Ë N northwards within the MOCÏă upper limb (Ïă0Â |
|
|
|
|
|
|