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| Titel |
Water Column Structure and Statistics of Denmark Strait Overflow Water Cyclones |
| VerfasserIn |
Wilken-Jon von Appen, Robert S. Pickart |
| 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 |
250072836
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| Zusammenfassung |
| It has long been known that the dense water flowing through Denmark Strait forms eddies
that propagate equatorward along the East Greenland continental slope. However, the lack of
in-situ measurements to date has made it difficult to assess their role in the North
Atlantic Meridional Overturning Circulation. Using data from a high-resolution
mooring array deployed 280Â km downstream of Denmark Strait, we investigate
the occurrence, structure, and dynamics of the Denmark Strait Overflow Water
cyclones. The cyclones pass the array roughly every two days and are most often found
near the 900Â m isobath. There is no seasonality to either their frequency or their
location on the slope. A composite cyclone was constructed using the year-long data
set. This revealed that, on average, the features self-propagate at 0.45Â m/s and
are also advected by the depth-mean background flow of 0.27Â m/s, leading to a
total propagation speed of 0.72Â m/s. The velocity field of a typical cyclone has a
Gaussian structure with a radius of 7.8Â km and a peak azimuthal speed of 0.22Â m/s. A
300Â m-thick lens of Denmark Strait Overflow Water (denser than 27.8Â kg/m3)
is contained within the bottom of the feature, situated below the peak azimuthal
speed. The influence of the cyclones on the sea surface temperature (SST) field is
investigated using concurrent satellite data. We find that disturbances to the shelfbreak
SST front propagate significantly slower than the underlying cyclones, suggesting
that SST imagery may be unsuitable for accurately tracking the subsurface eddies. |
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