Norwegian Atlantic Slope Current along the Lofoten Escarpment
<p>Observations from moored instruments are analyzed to describe the Norwegian Atlantic Slope Current at the Lofoten Escarpment (13<span class="inline-formula"><sup>∘</sup></span> E, 69<span class="inline-formula"><sup>∘</su...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-06-01
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| Series: | Ocean Science |
| Online Access: | https://www.ocean-sci.net/16/685/2020/os-16-685-2020.pdf |
| _version_ | 1819017078532734976 |
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| author | I. Fer A. Bosse A. Bosse J. Dugstad |
| author_facet | I. Fer A. Bosse A. Bosse J. Dugstad |
| author_sort | I. Fer |
| collection | DOAJ |
| description | <p>Observations from moored instruments are analyzed to describe the Norwegian Atlantic Slope Current at the Lofoten Escarpment (13<span class="inline-formula"><sup>∘</sup></span> E, 69<span class="inline-formula"><sup>∘</sup></span> 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<span class="inline-formula"><sup>−1</sup></span>, with the strongest currents in winter, and a temporal average of 0.15 m s<span class="inline-formula"><sup>−1</sup></span>. Higher-frequency variability is characterized by fluctuations that reach 0.8 m s<span class="inline-formula"><sup>−1</sup></span>, lasting for 1 to 2 weeks, and extend as deep as 600 m. In contrast to observations in Svinøy (2<span class="inline-formula"><sup>∘</sup></span> E, 63<span class="inline-formula"><sup>∘</sup></span> N), the slope current is not barotropic and varies strongly with depth (a shear of 0.05 to 0.1 m s<span class="inline-formula"><sup>−1</sup></span> per 100 m in all seasons). Within the limitations of the data, the average volume transport of Atlantic Water is estimated at <span class="inline-formula">2.0±0.8</span> Sv (1 Sv <span class="inline-formula">=10<sup>6</sup></span> m<span class="inline-formula"><sup>3</sup></span> s<span class="inline-formula"><sup>−1</sup></span>), with summer and winter averages of 1.6 and 2.9 Sv, respectively. The largest transport is associated with the high temperature classes (<span class="inline-formula">>7</span> <span class="inline-formula"><sup>∘</sup></span>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<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>)</mo><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">4</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="fd70519f5e945fdff883e51004a0c647"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-16-685-2020-ie00001.svg" width="39pt" height="15pt" src="os-16-685-2020-ie00001.png"/></svg:svg></span></span> W m<span class="inline-formula"><sup>−3</sup></span>.</p> |
| first_indexed | 2024-12-21T02:57:48Z |
| format | Article |
| id | doaj.art-271b3c55b9b34c4598785b24daf94c17 |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-12-21T02:57:48Z |
| publishDate | 2020-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-271b3c55b9b34c4598785b24daf94c172022-12-21T19:18:16ZengCopernicus PublicationsOcean Science1812-07841812-07922020-06-011668570110.5194/os-16-685-2020Norwegian Atlantic Slope Current along the Lofoten EscarpmentI. Fer0A. Bosse1A. Bosse2J. Dugstad3Geophysical institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, NorwayGeophysical institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norwaynow at: Aix-Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, Marseille, FranceGeophysical institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norway<p>Observations from moored instruments are analyzed to describe the Norwegian Atlantic Slope Current at the Lofoten Escarpment (13<span class="inline-formula"><sup>∘</sup></span> E, 69<span class="inline-formula"><sup>∘</sup></span> 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<span class="inline-formula"><sup>−1</sup></span>, with the strongest currents in winter, and a temporal average of 0.15 m s<span class="inline-formula"><sup>−1</sup></span>. Higher-frequency variability is characterized by fluctuations that reach 0.8 m s<span class="inline-formula"><sup>−1</sup></span>, lasting for 1 to 2 weeks, and extend as deep as 600 m. In contrast to observations in Svinøy (2<span class="inline-formula"><sup>∘</sup></span> E, 63<span class="inline-formula"><sup>∘</sup></span> N), the slope current is not barotropic and varies strongly with depth (a shear of 0.05 to 0.1 m s<span class="inline-formula"><sup>−1</sup></span> per 100 m in all seasons). Within the limitations of the data, the average volume transport of Atlantic Water is estimated at <span class="inline-formula">2.0±0.8</span> Sv (1 Sv <span class="inline-formula">=10<sup>6</sup></span> m<span class="inline-formula"><sup>3</sup></span> s<span class="inline-formula"><sup>−1</sup></span>), with summer and winter averages of 1.6 and 2.9 Sv, respectively. The largest transport is associated with the high temperature classes (<span class="inline-formula">>7</span> <span class="inline-formula"><sup>∘</sup></span>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<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>)</mo><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">4</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="fd70519f5e945fdff883e51004a0c647"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-16-685-2020-ie00001.svg" width="39pt" height="15pt" src="os-16-685-2020-ie00001.png"/></svg:svg></span></span> W m<span class="inline-formula"><sup>−3</sup></span>.</p>https://www.ocean-sci.net/16/685/2020/os-16-685-2020.pdf |
| spellingShingle | I. Fer A. Bosse A. Bosse J. Dugstad Norwegian Atlantic Slope Current along the Lofoten Escarpment Ocean Science |
| title | Norwegian Atlantic Slope Current along the Lofoten Escarpment |
| title_full | Norwegian Atlantic Slope Current along the Lofoten Escarpment |
| title_fullStr | Norwegian Atlantic Slope Current along the Lofoten Escarpment |
| title_full_unstemmed | Norwegian Atlantic Slope Current along the Lofoten Escarpment |
| title_short | Norwegian Atlantic Slope Current along the Lofoten Escarpment |
| title_sort | norwegian atlantic slope current along the lofoten escarpment |
| url | https://www.ocean-sci.net/16/685/2020/os-16-685-2020.pdf |
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