 |
| Titel |
Mixed layer lateral eddy fluxes mediated by air-sea interaction |
| VerfasserIn |
Emily Shuckburgh, Guillaume Maze, David Ferreira, John Marshall |
| Konferenz |
EGU General Assembly 2010
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041041
|
|
|
|
|
|
| Zusammenfassung |
| The modulation of air-sea heat fluxes by geostrophic eddies due to the stirring of temperature
at the sea surface is discussed and quantified. It is argued that the damping of eddy
temperature variance by such air-sea fluxes enhances the dissipation of surface temperature
fields. Depending on the timescale of damping relative to that of the eddying motions,
surface eddy diffusivities can be significantly enhanced over interior values. The
issues are explored and quantified in a controlled setting by driving a tracer field,
a proxy for sea-surface temperature, with surface altimetric observations in the
Antarctic Circumpolar Current (ACC) of the Southern Ocean. A new, tracer-based
diagnostic of eddy diffusivity is introduced which is related to the Nakamura effective
diffusivity. Using this, we quantify the surface lateral eddy diffusivities associated
with (i) eddy stirring and small-scale mixing and (ii) surface damping by air-sea
interaction. In the ACC, a diffusivity associated with surface damping of a comparable
magnitude to that associated with eddy stirring (~500m2/s) is found. In frontal regions
prevalent in the ACC, an augmentation of surface lateral eddy diffusivities of this
magnitude is equivalent to an air-sea flux of 100W/m2 acting over a mixed layer
depth of 100m – a very significant effect. Finally, the implications of our results for
other tracer fields such as salinity, dissolved gases and chlorophyll are discussed. |
|
|
|
|
|
|