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| Titel |
Mesoscale turbulence properties in the North-East Atlantic from altimetry and ADCP observations |
| VerfasserIn |
P. Lherminier, Patrice Klein, L. Dumas |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062480
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| Zusammenfassung |
| The North-East Atlantic ocean is characterized by a mesoscale turbulence which
properties, in terms of eddy kinetic redistribution and impact on the large-scale
circulation, are not well known. We have analysed these properties by using four years of
ADCP measurements taken as part of the Ovide project during the summer time. The
ADCP transects (about 1000Â km) are close and quasi-parallel to three altimeter
tracks.
We show that the spectral characteristics of the Sea Surface Height (SSH) deduced
from the along-track altimetry observations are very close to those of the stream
function (SF) deduced from the ADCP data: SSH and SF spectral slopes are close to
k-4 with k the wavenumber. Such slopes are shallower than expected from the
quasi-geostrophy (QG) turbulence theory (k-5 - k-6) but similar to those predicted by
Surface Quasi-Geostrophic (SQG) theory (k-11-3), which highlights the impact of small
scales.
These spectral characteristics from two independent datasets are consistent with recent
theoretical and DNS results. As such, they strongly suggest that the mesoscale and
submesoscale surface frontal dynamics impacts the mesoscale turbulence during the summer
time, with the consequence of a significant inverse kinetic energy cascade over a large scale
range.
This good agreement between SSH and SF spectral characteristics has to be contrasted
with recent results in the North-West Atlantic that reported a SSH spectral slope in k-4 and a
SF spectral slope slightly steeper than k-5. Some explanations for this discrepancy, in terms
of eddy turbulence, are proposed. |
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