 |
| Titel |
On the thermally-driven ocean |
| VerfasserIn |
Ada Gjermundsen, Joseph Henry LaCasce, Liv Denstad |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250152756
|
| Publikation (Nr.) |
 EGU/EGU2017-17636.pdf |
|
|
|
|
|
| Zusammenfassung |
| How will the ocean circulation respond to extensive temperature change? Warming over the
Arctic Ocean due to the loss of sea ice and snow cover will impact the surface air temperature
(Serreze and Farncis, 2006; Screen and Simmonds, 2010) and thereby the Northern
Hemisphere (NH) temperature gradient. The ocean circulation will respond, but freshwater
from ice melting and shifting storm tracks make it hard to determine the ocean response to
temperature changes alone. Attempts have been made to separate the impact of
wind, thermal and freshwater forcings on the large scale ocean circulation (Cai,
1994; Saenko et al., 2002; Nycander et al. 2007), but our understanding remains
incomplete.
Here we examine numerical solutions of the global circulation with realistic bathymetry,
driven solely by surface buoyancy forcing. Explicit wind forcing is excluded, although
vertical mixing is retained. The character of the resulting flow is consistent in many ways
with the observed ocean circulation,with inflow to and sinking in the Nordic Seas, baroclinic
western boundary currents and an overturning streamfunction which closely resembles those
obtained in full GCMs and in observations.
The overturning circulation exhibits two thermally-driven cells: one in the Southern Ocean
(SO) and one in the Atlantic. We investigate the inter-basin transports, the relative importance
of the two overturning cells for the global ocean circulation, as well as the sensitivity of the
ocean circulation to changes in buoyancy forcing. We find that reduced Atlantic overturning
accelerates the SO circulation, while a reduced SO circulation strengthens the Atlantic
overturning considerably.
References:
Cai, W. (1994). Circulation driven by observed surface thermohaline fields in a
coarse resolution ocean general circulation model. J. Geophys. Res.: Oceans, 99,
10163–10181.
Nycander, J. et al. (2007). Thermodynamic Analysis of Ocean Circulation, J. Phys.
Oceanogr., 37, 2038-2052.
Saenko, O. A. et al. (2002). Distinguishing the influence of heat, freshwater, and momentum
fluxes on ocean circulation and climate, J. Clim., 15, 3686–3697.
Screen. J. and Simmonds, I. (2010). The central role of diminishing sea ice in recent Arctic
temperature amplification, Nature, 464, 1334–1337.
Serreze, M. C. and Francis, J. A. (2006). The Arctic Amplification Debate, Climatic
Change, 76, 241–264. |
|
|
|
|
|
|