Wind-forced depth-dependent currents over the eastern Beaufort Sea continental slope: Implications for Pacific water transport
Pacific water contributes significantly to the Arctic Ocean freshwater budget. Recent increases in Arctic freshwater flux, also affected by the Pacific-derived Arctic water, impact the Atlantic overturning circulation with implications for global climate. The interannual variability of the Pacific w...
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doaj-0e142ad0ca4c4ddba6bab9cbce1bf8d42020-11-24T21:48:38ZengBioOneElementa: Science of the Anthropocene2325-10262018-10-016110.1525/elementa.321292Wind-forced depth-dependent currents over the eastern Beaufort Sea continental slope: Implications for Pacific water transportIgor A. Dmitrenko0Sergei A. Kirillov1Paul G. Myers2Alexandre Forest3Bruno Tremblay4Jennifer V. Lukovich5Yves Gratton6Søren Rysgaard7David G. Barber8Centre for Earth Observation Science, University of Manitoba, Winnipeg, ManitobaCentre for Earth Observation Science, University of Manitoba, Winnipeg, ManitobaDepartment of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AlbertaLaval University, QuebecMcGill University, Montreal, QuebecCentre for Earth Observation Science, University of Manitoba, Winnipeg, ManitobaInstitut National de la Recherche Scientifique – Eau Terre Environnement, QuebecCentre for Earth Observation Science, University of Manitoba, Winnipeg, Manitoba, CA; Arctic Research Centre, Aarhus UniversityCentre for Earth Observation Science, University of Manitoba, Winnipeg, ManitobaPacific water contributes significantly to the Arctic Ocean freshwater budget. Recent increases in Arctic freshwater flux, also affected by the Pacific-derived Arctic water, impact the Atlantic overturning circulation with implications for global climate. The interannual variability of the Pacific water outflow remains poorly understood, partly due to different branches of the Pacific water flow in the Arctic Ocean. The shelfbreak current over the Beaufort Sea continental slope transports ~50% of the Pacific-derived water eastward along the Beaufort Sea continental slope towards the Canadian Archipelago. The oceanographic mooring deployed over the eastern Beaufort Sea continental slope in October 2003 recorded current velocities through depths of 28–108 m until September 2005. Data analysis revealed that these highly energetic currents have two different modes of depth-dependent behaviour. The downwelling-favourable wind associated with cyclones passing north of the Beaufort Sea continental slope toward the Canadian Archipelago generates depth-intensified shelfbreak currents with along-slope northeastward flow. A surface Ekman on-shore transport and associated increase of the sea surface heights over the shelf produce a cross-slope pressure gradient that drives an along-slope northeastward barotropic flow, in the same direction as the wind. In contrast, the upwelling-favourable wind associated with deep Aleutian Low cyclones over the Alaskan Peninsula and/or Aleutian Island Arc leads to surface-intensified currents with along-slope westward flow. This northeasterly wind generates a surface Ekman transport that moves surface waters offshore. The associated cross-slope pressure gradient drives an along-slope southwestward barotropic flow. The wind-driven barotropic flow generated by upwelling and downwelling is superimposed on the background bottom-intensified shelfbreak current. For downwelling, this flow amplifies the depth-intensified background baroclinic circulation with enhanced Pacific water transport towards the Canadian Archipelago. For upwelling, the shelfbreak current is reversed, which results in surface-intensified flow in the opposite direction. These results are supported by numerical simulations.https://www.elementascience.org/articles/321UpwellingDownwellingDepth-dependent currentsPacific water |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Igor A. Dmitrenko Sergei A. Kirillov Paul G. Myers Alexandre Forest Bruno Tremblay Jennifer V. Lukovich Yves Gratton Søren Rysgaard David G. Barber |
spellingShingle |
Igor A. Dmitrenko Sergei A. Kirillov Paul G. Myers Alexandre Forest Bruno Tremblay Jennifer V. Lukovich Yves Gratton Søren Rysgaard David G. Barber Wind-forced depth-dependent currents over the eastern Beaufort Sea continental slope: Implications for Pacific water transport Elementa: Science of the Anthropocene Upwelling Downwelling Depth-dependent currents Pacific water |
author_facet |
Igor A. Dmitrenko Sergei A. Kirillov Paul G. Myers Alexandre Forest Bruno Tremblay Jennifer V. Lukovich Yves Gratton Søren Rysgaard David G. Barber |
author_sort |
Igor A. Dmitrenko |
title |
Wind-forced depth-dependent currents over the eastern Beaufort Sea continental slope: Implications for Pacific water transport |
title_short |
Wind-forced depth-dependent currents over the eastern Beaufort Sea continental slope: Implications for Pacific water transport |
title_full |
Wind-forced depth-dependent currents over the eastern Beaufort Sea continental slope: Implications for Pacific water transport |
title_fullStr |
Wind-forced depth-dependent currents over the eastern Beaufort Sea continental slope: Implications for Pacific water transport |
title_full_unstemmed |
Wind-forced depth-dependent currents over the eastern Beaufort Sea continental slope: Implications for Pacific water transport |
title_sort |
wind-forced depth-dependent currents over the eastern beaufort sea continental slope: implications for pacific water transport |
publisher |
BioOne |
series |
Elementa: Science of the Anthropocene |
issn |
2325-1026 |
publishDate |
2018-10-01 |
description |
Pacific water contributes significantly to the Arctic Ocean freshwater budget. Recent increases in Arctic freshwater flux, also affected by the Pacific-derived Arctic water, impact the Atlantic overturning circulation with implications for global climate. The interannual variability of the Pacific water outflow remains poorly understood, partly due to different branches of the Pacific water flow in the Arctic Ocean. The shelfbreak current over the Beaufort Sea continental slope transports ~50% of the Pacific-derived water eastward along the Beaufort Sea continental slope towards the Canadian Archipelago. The oceanographic mooring deployed over the eastern Beaufort Sea continental slope in October 2003 recorded current velocities through depths of 28–108 m until September 2005. Data analysis revealed that these highly energetic currents have two different modes of depth-dependent behaviour. The downwelling-favourable wind associated with cyclones passing north of the Beaufort Sea continental slope toward the Canadian Archipelago generates depth-intensified shelfbreak currents with along-slope northeastward flow. A surface Ekman on-shore transport and associated increase of the sea surface heights over the shelf produce a cross-slope pressure gradient that drives an along-slope northeastward barotropic flow, in the same direction as the wind. In contrast, the upwelling-favourable wind associated with deep Aleutian Low cyclones over the Alaskan Peninsula and/or Aleutian Island Arc leads to surface-intensified currents with along-slope westward flow. This northeasterly wind generates a surface Ekman transport that moves surface waters offshore. The associated cross-slope pressure gradient drives an along-slope southwestward barotropic flow. The wind-driven barotropic flow generated by upwelling and downwelling is superimposed on the background bottom-intensified shelfbreak current. For downwelling, this flow amplifies the depth-intensified background baroclinic circulation with enhanced Pacific water transport towards the Canadian Archipelago. For upwelling, the shelfbreak current is reversed, which results in surface-intensified flow in the opposite direction. These results are supported by numerical simulations. |
topic |
Upwelling Downwelling Depth-dependent currents Pacific water |
url |
https://www.elementascience.org/articles/321 |
work_keys_str_mv |
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