 |
| Titel |
A vorticity budget for the Gulf Stream |
| VerfasserIn |
Isabela Le Bras, John Toole |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250146697
|
| Publikation (Nr.) |
 EGU/EGU2017-10735.pdf |
|
|
|
|
|
| Zusammenfassung |
| We develop a depth-averaged vorticity budget framework to diagnose the dynamical balance
of the Gulf Stream, and apply this framework to observations and the ECCO state
estimate (Wunsch and Heimbach 2013) above the thermocline in the subtropical North
Atlantic.
Using the hydrographic and ADCP data along the WOCE/CLIVAR section A22 and a
variety of wind stress data products, we find that the advective vorticity flux out of the
western region is on the same order as the wind stress forcing over the eastern portion of the
gyre. This is consistent with a large-scale balance between a negative source of vorticity from
wind stress forcing and a positive source of vorticity in the western region. Additionally, the
form of the vorticity flux indicates that the Gulf Stream has a significant inertial
component.
In the ECCO state estimate, we diagnose a seasonal cycle in advective vorticity flux
across a meridional section associated with seasonal fluctuations in Gulf Stream
transport. This vorticity flux is forced by wind stress over the eastern subtropical
North Atlantic and balanced by lateral friction with the western boundary. The
lateral friction in ECCO is a necessary parameterization of smaller scale processes
that occur in the real ocean, and quantifying these remains an open and interesting
question.
This simplified framework provides a means to interpret large scale ocean dynamics. In
our application, it points to wind stress forcing over the subtropical North Altantic as an
important regulator of the Gulf Stream and hence the climate system. |
|
|
|
|
|
|