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| Titel |
Surface heat budget at the Nordic Seas in Lagrangian observations |
| VerfasserIn |
Marta S. de La Lama, Pål E. Isachsen, Inga Koszalka, Joseph H. LaCasce |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250096544
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| Publikation (Nr.) |
 EGU/EGU2014-12052.pdf |
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| Zusammenfassung |
| In the Nordic Seas, the warm, inflowing Atlantic Water is cooled until it is dense enough to
sink. Thereafter it circulates at depth, eventually feeding the North Atlantic Deep Water. The
air-sea interaction which facilitates this cooling is a complex process involving diverse
phenomena, from surface heating to turbulent entrainment at the base of the ocean surface
mixed layer.
In the present study, we use 486 freely-drifting surface buoys to observe temperature
changes on water parcels and the response to air-sea heat fluxes. Such Lagrangian
observations advantageously “filter out” horizontal heat fluxes, since the buoys are advected
by the flow, allowing one to focus on the vertical exchanges.
We examine the temporal evolution of temperature on the drifters and the correlations
with surface heat fluxes, obtained from ECMWF ERA-Interim reanalyses. The frequency
spectra indicate a clear Ï-2 dependence at frequencies higher than roughly 1-40 days-1. The
temperature fluctuations on the other hand are correlated with surface fluxes only at the
longer time scales.
We then show how the Lagrangian temperature can be represented as a stochastic process,
with a deterministic portion determined by the low frequency atmospheric forcing
and a white noise perturbation. This is in line with previous studies of the ocean
surface response to stochastic wind forcing. What distinguishes the present model is
the deterministic part, which must account for the gradual cooling of the water
parcels. |
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