 |
| Titel |
Enhanced Atlantic subpolar gyre variability through baroclinic threshold in a coarse resolution model |
| VerfasserIn |
M. Mengel, A. Levermann, C.-F. Schleussner, Amandus Born |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
2190-4979
|
| Digitales Dokument |
URL |
| Erschienen |
In: Earth System Dynamics ; 3, no. 2 ; Nr. 3, no. 2 (2012-11-21), S.189-197 |
| Datensatznummer |
250001010
|
| Publikation (Nr.) |
 copernicus.org/esd-3-189-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| Direct observations, satellite measurements and paleo records reveal strong
variability in the Atlantic subpolar gyre on various time scales. Here we
show that variations of comparable amplitude can only be simulated in a
coupled climate model in the proximity of a dynamical threshold. The
threshold and the associated dynamic response is due to a positive feedback
involving increased salt transport in the subpolar gyre and enhanced deep
convection in its centre. A series of sensitivity experiments is performed
with a coarse resolution ocean general circulation model coupled to a
statistical-dynamical atmosphere model which in itself does not produce
atmospheric variability. To simulate the impact of atmospheric variability,
the model system is perturbed with freshwater forcing of varying, but small
amplitude and multi-decadal to centennial periodicities and observational
variations in wind stress. While both freshwater and wind-stress-forcing have
a small direct effect on the strength of the subpolar gyre, the magnitude of
the gyre's response is strongly increased in the vicinity of the threshold.
Our results indicate that baroclinic self-amplification in the North Atlantic
ocean can play an important role in presently observed SPG variability and
thereby North Atlantic climate variability on multi-decadal scales. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|