Publication Date:
2021-06-01
Description:
Five non-eddy-resolving oceanic general circulation models driven by atmospheric fluxes derived from
the NCEP reanalysis are used to investigate the link between the Gulf Stream (GS) variability, the atmospheric
circulation, and the Atlantic meridional overturning circulation (AMOC). Despite the limited
model resolution, the temperature at the 200-m depth along the mean GS axis behaves similarly in most
models to that observed, and it is also well correlated with the North Atlantic Oscillation (NAO), indicating
that a northward (southward) GS shift lags a positive (negative) NAO phase by 0–2 yr. The northward shift
is accompanied by an increase in the GS transport, and conversely the southward shift with a decrease in
the GS transport. Two dominant time scales appear in the response of the GS transport to the NAO forcing:
a fast time scale (less than 1 month) for the barotropic component, and a slower one (about 2 yr) for the
baroclinic component. In addition, the two components are weakly coupled. The GS response seems
broadly consistent with a linear adjustment to the changes in the wind stress curl, and evidence for baroclinic
Rossby wave propagation is found in the southern part of the subtropical gyre. However, the GS shifts are
also affected by basin-scale changes in the oceanic conditions, and they are well correlated in most models
with the changes in the AMOC. A larger AMOC is found when the GS is stronger and displaced northward,
and a higher correlation is found when the observed changes of the GS position are used in the comparison.
The relation between the GS and the AMOC could be explained by the inherent coupling between the
thermohaline and the wind-driven circulation, or by the NAO variability driving them on similar time scales
in the models.
Description:
This research was supported by
the PREDICATE project of the European Community,
and for M. Bentsen by the Research Council of
Norway through RegClim, NOClim, and the Programme
of Supercomputing.
Description:
Published
Description:
2119–2135
Description:
3.7. Dinamica del clima e dell'oceano
Description:
JCR Journal
Description:
reserved
Keywords:
ocean modelling
;
gulf stream variability
;
03. Hydrosphere::03.01. General::03.01.03. Global climate models
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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