scholarly journals One-dimensional evolution of the upper water column in the Atlantic sector of the Arctic Ocean in winter

2017 ◽  
Vol 122 (3) ◽  
pp. 1665-1682 ◽  
Author(s):  
Ilker Fer ◽  
Algot K. Peterson ◽  
Achim Randelhoff ◽  
Amelie Meyer
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
The Arctic ◽  
Atlantic Sector ◽  
One Dimensional ◽  
The Arctic Ocean

scholarly journals Structure and drivers of ocean mixing north of Svalbard in summer and fall 2018

2020 ◽  
Author(s):  
Zoe Koenig ◽  
Eivind H. Kolås ◽  
Ilker Fer
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
Mixed Layer ◽  
Tidal Currents ◽  
The Arctic ◽  
Turbulent Heat ◽  
Ocean Mixing ◽  
Atlantic Sector ◽  
The Arctic Ocean ◽  
Nonlinear Relation

Abstract. Ocean mixing in the Arctic Ocean cools and freshens the Atlantic and Pacific-origin waters by mixing them with surrounding waters, which has major implications on global scale as the Arctic Ocean is a main sink for heat and salt. We investigate the drivers of ocean mixing north of Svalbard, in the Atlantic sector of the Arctic, based on observations collected during two research cruises in summer and fall 2018. In the mixed layer, there is a nonlinear relation between the layer-integrated dissipation and wind energy input; convection was active at a few stations and was responsible for enhanced turbulence compare to what was expected from the wind work alone. Summer melting of sea ice reduces the temperature, salinity and depth of the mixed layer, and increases salt and buoyancy fluxes at the base of the mixed layer. Deeper in the water column and near the seabed, tidal work is a main source of turbulence: diapycnal diffusivity in the bottom 250 m of the water column is enhanced during strong tidal currents, reaching on average 10−3 m2 s−1. The average profile of diffusivity decays with distance from seabed with an e-folding scale of 22 m compared to 18 m in conditions with weaker tidal currents. A nonlinear relation is inferred between the depth-integrated dissipation in the bottom 250 m of the water column and the tidally-driven bottom drag and is used to estimate the bottom dissipation along the continental slope of the Eurasian Basin. Computation of the inverse Froude number suggests that nonlinear internal waves forced by the diurnal tidal activity (K1 constituent) can develop north of Svalbard and in the Laptev and Kara Seas, with the potential to mix the entire water column vertically. Estimates of vertical turbulent heat flux from the Atlantic Water layer up to the mixed layer reaches 30 W m−2 in the core of the boundary current, and is on average 8 W m−2, accounting for ∼ 1 % of the total heat loss of the Atlantic layer in the region.

scholarly journals Structure and drivers of ocean mixing north of Svalbard in summer and fall 2018

Ocean Science ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 365-381
Author(s):  
Zoe Koenig ◽  
Eivind H. Kolås ◽  
Ilker Fer
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
Mixed Layer ◽  
Tidal Currents ◽  
The Arctic ◽  
Global Ocean ◽  
Ocean Mixing ◽  
Atlantic Sector ◽  
The Arctic Ocean ◽  
Nonlinear Relation

Abstract. The Arctic Ocean is a major sink for heat and salt for the global ocean. Ocean mixing contributes to this sink by mixing the Atlantic- and Pacific-origin waters with surrounding waters. We investigate the drivers of ocean mixing north of Svalbard, in the Atlantic sector of the Arctic, based on observations collected during two research cruises in summer and fall 2018. Estimates of vertical turbulent heat flux from the Atlantic Water layer up to the mixed layer reach 30 W m−2 in the core of the boundary current, and average to 8 W m−2, accounting for ∼1 % of the total heat loss of the Atlantic layer in the region. In the mixed layer, there is a nonlinear relation between the layer-integrated dissipation and wind energy input; convection was active at a few stations and was responsible for enhanced turbulence compared to what was expected from the wind stress alone. Summer melting of sea ice reduces the temperature, salinity and depth of the mixed layer and increases salt and buoyancy fluxes at the base of the mixed layer. Deeper in the water column and near the seabed, tidal forcing is a major source of turbulence: diapycnal diffusivity in the bottom 250 m of the water column is enhanced during strong tidal currents, reaching on average 10−3 m2 s−1. The average profile of diffusivity decays with distance from the seabed with an e-folding scale of 22 m compared to 18 m in conditions with weaker tidal currents. A nonlinear relation is inferred between the depth-integrated dissipation in the bottom 250 m of the water column and the tidally driven bottom drag and is used to estimate the bottom dissipation along the continental slope of the Eurasian Basin. Computation of an inverse Froude number suggests that nonlinear internal waves forced by the diurnal tidal currents (K1 constituent) can develop north of Svalbard and in the Laptev and Kara seas, with the potential to mix the entire water column vertically. Understanding the drivers of turbulence and the nonlinear pathways for the energy to turbulence in the Arctic Ocean will help improve the description and representation of the rapidly changing Arctic climate system.

scholarly journals Attribution of the Recent Winter Sea Ice Decline over the Atlantic Sector of the Arctic Ocean*

2015 ◽  
Vol 28 (10) ◽  
pp. 4027-4033 ◽  
Author(s):  
Doo-Sun R. Park ◽  
Sukyoung Lee ◽  
Steven B. Feldstein
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Environmental Changes ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Positive Trend ◽  
Ir Radiation ◽  
Atlantic Sector ◽  
Sea Ice Decline ◽  
The Arctic Ocean

Abstract Wintertime Arctic sea ice extent has been declining since the late twentieth century, particularly over the Atlantic sector that encompasses the Barents–Kara Seas and Baffin Bay. This sea ice decline is attributable to various Arctic environmental changes, such as enhanced downward infrared (IR) radiation, preseason sea ice reduction, enhanced inflow of warm Atlantic water into the Arctic Ocean, and sea ice export. However, their relative contributions are uncertain. Utilizing ERA-Interim and satellite-based data, it is shown here that a positive trend of downward IR radiation accounts for nearly half of the sea ice concentration (SIC) decline during the 1979–2011 winter over the Atlantic sector. Furthermore, the study shows that the Arctic downward IR radiation increase is driven by horizontal atmospheric water flux and warm air advection into the Arctic, not by evaporation from the Arctic Ocean. These findings suggest that most of the winter SIC trends can be attributed to changes in the large-scale atmospheric circulations.

chapter 7 Carbon Export Efficiency and Phytoplankton Community Composition in the Atlantic Sector of the Arctic Ocean

2017 ◽  
pp. 149-188
Author(s):  
FRÉDÉRIC A. C. LE MOIGNE ◽  
ALEX J. POULTON ◽  
STEPHANIE A. HENSON ◽  
CHRIS J. DANIELS ◽  
GLAUCIA M. FRAGOSO ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Community Composition ◽  
Phytoplankton Community ◽  
The Arctic ◽  
Carbon Export ◽  
Atlantic Sector ◽  
Phytoplankton Community Composition ◽  
The Arctic Ocean

scholarly journals Modelling the effect of boundary scavenging on Thorium and Protactinium profiles in the ocean

2009 ◽  
Vol 6 (4) ◽  
pp. 7853-7896 ◽  
Author(s):  
M. Roy-Barman
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
Open Ocean ◽  
The Arctic ◽  
Transport Parameters ◽  
Lateral Transport ◽  
Transport Reaction ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Boundary Scavenging

Abstract. The "boundary scavenging" box model is a cornerstone of our understanding of the particle-reactive radionuclide fluxes between the open ocean and the ocean margins. However, it does not describe the radionuclide profiles in the water column. Here, I present the transport-reaction equations for radionuclides transported vertically by reversible scavenging on settling particles and laterally by horizontal currents between the margin and the open ocean. Analytical solutions of these equations are compared with existing data. In the Pacific Ocean, the model produces "almost" linear 230Th profiles (as observed in the data) despite lateral transport. However, omitting lateral transport biased the 230Th based particle flux estimates by as much as 50%. 231Pa profiles are well reproduced in the whole water column of the Pacific Margin and from the surface down to 3000 m in the Pacific subtropical gyre. Enhanced bottom scavenging or inflow of 231Pa-poor equatorial water may account for the model-data discrepancy below 3000 m. The lithogenic 232Th is modelled using the same transport parameters as 230Th but a different source function. The main source of 232Th scavenged in the open Pacific is advection from the ocean margin, whereas a net flux of 230Th produced in the open Pacific is advected and scavenged at the margin, illustrating boundary exchange. In the Arctic Ocean, the model reproduces 230Th measured profiles that the uni-dimensional scavenging model or the scavenging-ventilation model failed to explain. Moreover, if lateral transport is ignored, the 230Th based particle settling speed may by underestimated by a factor 4 at the Arctic Ocean margin. The very low scavenging rate in the open Arctic Ocean combined with the enhanced scavenging at the margin accounts for the lack of high 231Pa/230Th ratio in arctic sediments.

Implementation of a multipurpose Arctic Ocean Observing System

2020 ◽  
Author(s):  
Stein Sandven ◽  
Hanne Sagen ◽  
Agnieszka Beszczynska-Möller ◽  
Peter Vo ◽  
Marie-Noelle Houssais ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Water Column ◽  
The Arctic ◽  
Sea Floor ◽  
Acoustic Thermometry ◽  
The Arctic Ocean ◽  
Global Coverage ◽  
Cable Systems ◽  
Ocean Observing ◽  
Observing Systems

<p>The central Arctic Ocean is one of the least observed oceans in the world. This ice-covered region is challenging for ocean observing with respect to technology, logistics and costs. Many physical, biogeochemical, biological, and geophysical processes in the water column and sea floor under the sea ice are difficult to observe and therefore poorly understood. Today, there are technological advances in platforms and sensors for under-ice observation, which offer possibilities to install and operate sustained observing infrastructures in the Arctic Ocean. The goal of the INTAROS project is to develop integrated observing systems in the Arctic, including improvement of data sharing and dissemination to various user groups. INTAROS supports a number of systems providing data from the ocean in delayed mode as well as in near-real time mode, but only a few operate in the ice-covered areas.</p><p>Autonomous observing platforms used in the ice-free oceans such as Argo floats, gliders, and autonomous surface vehicles cannot yet be used operationally in ice-covered Arctic regions. The limitation is because the sea ice prevents these underwater platforms from reaching the surface for satellite communication and geopositioning. To improve the Arctic Ocean Observing capability OceanObs19 recommended ‘to pilot a sustained multipurpose acoustic network for positioning, tomography, passive acoustics, and communication in an integrated Arctic Observing System, with eventual transition to global coverage’. Acoustic networks have been used locally and regionally in the Arctic for underwater acoustic thermometry, geo-positioning for floats and gliders, and passive acoustic. The Coordinated Arctic Acoustic Thermometry Experiment (CAATEX) is a first step toward developing a basin-scale multipurpose acoustic network using modern instrumentation.</p><p>To provide secure data delivery, submarine cables are needed either as dedicated cabled observatories or as hybrid cable systems (sharing the cable infrastructure between science and commercial telecommunications), or both combined. Several large-scale cabled observatories existing coastal areas in world oceans, but none on the Arctic Ocean. At OceanObs19 it was recommended to transition (telecom+sensing) SMART subsea cable systems from present pilots to trans-ocean implementation, to address climate, ocean circulation, sea level, tsunami and earthquake early warning, ultimately with global coverage. Cabled observatories, either stand alone or branching from a hybrid system, could provide power and real time communication to support connected water column moorings and sea floor instrumentation as well as docking mobile platforms. Subsea cable developers are looking into the possibility to deploy a communication cable across the Arctic Ocean from Europe to Asia, because this offers a much shorter route compared to the terrestrial cables.</p><p> An international consortium of leading scientists in ocean observing with experience in state-of-the-art technologies on platforms, sensors, subsea cable technology, acoustic communication and data transmission plan to establish a project to implement and test the system based on experience from the CAATEX experiment and other Arctic observing system experiments. The INTAROS project is presently developing a Roadmap for an integrated Arctic Observing System, where multipurpose ocean observing systems will be one component.</p>

scholarly journals Vertical fluxes of nitrate in the seasonal nitracline of the Atlantic sector of the Arctic Ocean

2016 ◽  
Vol 121 (7) ◽  
pp. 5282-5295 ◽  
Author(s):  
Achim Randelhoff ◽  
Ilker Fer ◽  
Arild Sundfjord ◽  
Jean‐Éric Tremblay ◽  
Marit Reigstad
Keyword(s):  
Arctic Ocean ◽  
The Arctic ◽  
Atlantic Sector ◽  
Vertical Fluxes ◽  
The Arctic Ocean

scholarly journals How well does wind speed predict air-sea gas transfer in the sea ice zone? A synthesis of radon deficit profiles in the upper water column of the Arctic Ocean

2017 ◽  
Vol 122 (5) ◽  
pp. 3696-3714 ◽  
Author(s):  
B. Loose ◽  
R. P. Kelly ◽  
A. Bigdeli ◽  
W. Williams ◽  
R. Krishfield ◽  
...  
Keyword(s):  
Wind Speed ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Water Column ◽  
The Arctic ◽  
Gas Transfer ◽  
The Arctic Ocean
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