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| Titel |
Lateral Diffusivity from Tracer Release Experiments in the Tropical North Atlantic Thermocline |
| VerfasserIn |
Donata Banyte, Martin Visbeck, Toste Tanhua, Tim Fischer, Gerd Krahmann, Johannes Karstensen |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250078850
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| Zusammenfassung |
| Lateral diffusivity is computed from a tracer release experiment in the northeastern tropical
Atlantic thermocline. The uncertainties of the estimates are inferred from a synthetic
particle release using a high resolution ocean circulation model. The main method
employed to compute zonal and meridional components of lateral diffusivity is
the growth of the second moment of a cloud of tracer. The application of an areal
comparison method for tracer-based ’effective diffusivity’ in the field experiments is also
discussed. The best estimate of meridional eddy diffusivity in the Guinea Upwelling
region at about 300 m depth is estimated to be Ky ~ 500 m2 s-1 (300 - 700).
The zonal component of lateral diffusivity is estimated to be Kx = 1200 m2 s-1
(600 - 1800). In comparison to Ky, Kx is almost twice larger, resulting from the
tracer patch stretching by zonal jets. Employed conceptual jet model indicates that
zonal jet velocities of about 0.01 m s-1 (0.005 - 0.02) are required to explain the
enhancement of the zonal eddy diffusivity component. Overall, the effective eddy
diffusivity is estimated to be Ke = 700 m2 s-1 (500 - 900). Finally, different sampling
strategies are tested on synthetic tracer release experiments. They indicate that the best
sampling strategy is a sparse regular sampling grid covering most of the tracer
patch. |
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