insu-03668097
https://insu.hal.science/insu-03668097
https://insu.hal.science/insu-03668097/document
https://insu.hal.science/insu-03668097/file/os-16-685-2020.pdf
doi:10.5194/os-16-685-2020
[IRD] IRD - Institut de recherche pour le développement
[INSU] INSU - Institut National des Sciences de l'Univers
[UNIV-TLN] Université de Toulon
[CNRS] CNRS - Centre national de la recherche scientifique
[UNIV-AMU] Aix Marseille Université
[MIO] Institut Méditerranéen d'Oceanologie - Mediterranean Institute of Oceanography (MIO)
[OSU-INSTITUT-PYTHEAS] OSU INSTITUT PYTHEAS
[GIP-BE] GIP Bretagne Environnement
Norwegian Atlantic Slope Current along the Lofoten Escarpment
Fer, Ilker
Bosse, Anthony
Dugstad, Johannes
[SDU] Sciences of the Universe [physics]
[SDU.STU.OC] Sciences of the Universe [physics]/Earth Sciences/Oceanography
ART
Observations from moored instruments are analyzed to describe the Norwegian Atlantic Slope Current at the Lofoten Escarpment (13<SUP>∘</SUP> E, 69<SUP>∘</SUP> N). The data set covers a 14-month period from June 2016 to September 2017 and resolves the core of the current from 200 to 650 m depth between the 650 and 1500 m isobaths. The along-isobath current, vertically averaged between 200 and 600 m depth, has an annual cycle amplitude of 0.1 m s<SUP>-1</SUP>, with the strongest currents in winter, and a temporal average of 0.15 m s<SUP>-1</SUP>. Higher-frequency variability is characterized by fluctuations that reach 0.8 m s<SUP>-1</SUP>, lasting for 1 to 2 weeks, and extend as deep as 600 m. In contrast to observations in Svinøy (2<SUP>∘</SUP> E, 63<SUP>∘</SUP> N), the slope current is not barotropic and varies strongly with depth (a shear of 0.05 to 0.1 m s<SUP>-1</SUP> per 100 m in all seasons). Within the limitations of the data, the average volume transport of Atlantic Water is estimated at 2.0±0.8 Sv (1 Sv =10<SUP>6</SUP> m<SUP>3</SUP> s<SUP>-1</SUP>), with summer and winter averages of 1.6 and 2.9 Sv, respectively. The largest transport is associated with the high temperature classes (>7 <SUP>∘</SUP>C) in all seasons, with the largest values of both transport and temperature in winter. Calculations of the barotropic and baroclinic conversion rates using the moorings are supplemented by results from a high-resolution numerical model. While the conversion from mean to eddy kinetic energy (e.g., barotropic instability) is likely negligible over the Lofoten Escarpment, the baroclinic conversion from mean potential energy into eddy kinetic energy (e.g., baroclinic instability) can be substantial, with volume-averaged values of (1-2)×<SUP>10-4</SUP> W m<SUP>-3</SUP>.
2020
2022-05-14
en
http://creativecommons.org/licenses/by/
OCEAN SCIENCE