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| Titel |
Fronts and intrusions in the upper Deep Polar Water of the Eurasian and Makarov basins |
| VerfasserIn |
Natalia Kuzmina, Bert Rudels, Natalia Zhurbas, Dmitry Lyzhkov |
| 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 |
250076046
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| Zusammenfassung |
| CTD data obtained in the Arctic Basin are analyzed to describe structural features of
intrusive layers and fronts encountered in the upper Deep Polar Water. This work is an
extension of Arctic intrusions studies by Rudels et al. (1999) and Kuzmina et al.
(2011).
Numerous examples of fronts and intrusions observed in a deep layer (depth range of
600–1300 m) in the Eurasian and Makarov basins where salinity is increasing, and
temperature is decreasing with depth (stable-stable thermohaline stratification), are described.
The data are used to estimate hydrological parameters capable of determining different types
of fronts and characterizing intrusive layers depending on the front structure. Coherence of
intrusive layers is shown to get broken with the change of front structure. An evidence is
found that enhanced turbulent mixing above local bottom elevations can prevent from
intrusive layering.
A linear stability model description of the observed intrusions is developed based on the
Merryfield’s (2000) assumption that interleaving is caused by differential mixing. Theoretical
analysis is focused on prediction of the slopes of unstable modes at baroclinic and
thermohaline fronts.
Apparent vertical diffusivity due to turbulent mixing at baroclinic and thermohaline fronts
is estimated on the basis of comparison of observed intrusion slopes with modeled
slopes of the most unstable modes. Apparent lateral diffusivity is estimated too,
based on Joyce (1980) approach. These estimates show that intrusive instability of
fronts caused by differential mixing can result in sizable values of apparent lateral
heat diffusivity in the deep Arctic layer that are quite comparable with those of the
upper and intermediate Arctic layers (Walsh, Carmack, 2003; Kuzmina et al., 2011). |
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