Turbulence Observations Below Drifting Sea Ice: TKE Production and Dissipation in the Meltwater-Influenced Boundary Layer

Simon F. Reifenberg aAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany

Search for other papers by Simon F. Reifenberg in
Current site
Google Scholar
PubMed
Close
,
Ilker Fer bGeophysical Institute, University of Bergen, and Bjerknes Center for Climate Research, Bergen, Norway

Search for other papers by Ilker Fer in
Current site
Google Scholar
PubMed
Close
,
Torsten Kanzow aAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
cInstitute of Environmental Physics, University of Bremen, Bremen, Germany

Search for other papers by Torsten Kanzow in
Current site
Google Scholar
PubMed
Close
,
Wilken-Jon von Appen aAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany

Search for other papers by Wilken-Jon von Appen in
Current site
Google Scholar
PubMed
Close
,
Mario Hoppmann aAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany

Search for other papers by Mario Hoppmann in
Current site
Google Scholar
PubMed
Close
,
Thomas Krumpen aAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany

Search for other papers by Thomas Krumpen in
Current site
Google Scholar
PubMed
Close
,
Mara Neudert aAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany

Search for other papers by Mara Neudert in
Current site
Google Scholar
PubMed
Close
,
Andreas Preußer aAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany

Search for other papers by Andreas Preußer in
Current site
Google Scholar
PubMed
Close
, and
Christian Haas aAlfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
cInstitute of Environmental Physics, University of Bremen, Bremen, Germany

Search for other papers by Christian Haas in
Current site
Google Scholar
PubMed
Close
Full access

Abstract

During Arctic summer, meltwater inputs and a fragmented ice cover impede quantifying the role of boundary stress for turbulent mixing in the ice-ocean boundary layer. Here we show that less than two-thirds of the turbulent kinetic energy (TKE) generated from mean flow shear under drifting sea ice is dissipated, and the remainder can be attributed to balancing stabilizing buoyancy fluxes. We deployed a high-resolution acoustic Doppler current profiler under an ice floe to estimate Reynolds stress, shear production and dissipation rate of TKE. At 0.75 m below the interface, dissipation rates from 1.5 × 10−9 to 4.2 × 10−7 m2 s−3, and shear production from 6.9×10−10 to 7.7×10−7 m2 s−3 were measured (5% to 95% percentiles), with shear production exceeding dissipation on average. The turbulent stress was largest during an event with ~ 9.2 h period oscillations in the upper ocean, consistent with tidally forced lee waves generated near steep topography. An overall estimate of the quadratic skin drag coefficient representative of the ice floe is CD0 = 7.0×10−4. We further identified three qualitative regimes of atmosphere-ice-ocean coupling in our observations: a high-frequency range (> 4 cycles per day, cpd) in which the ice acts like a rigid lid atop the ocean, an intermediate range, and a low-frequency range (< 0.8 cpd) where wind-driven ice drift determines the under-ice current. As the latter only contained half of the variance of the ice-relative flow, we emphasize that resolving sub-daily time scales is crucial in observing and modeling atmosphere-ice-ocean coupling.

© 2025 American Meteorological Society. This is an Author Accepted Manuscript distributed under the terms of the default AMS reuse license. For information regarding reuse and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: S. Reifenberg, simon.reifenberg@awi.de

Abstract

During Arctic summer, meltwater inputs and a fragmented ice cover impede quantifying the role of boundary stress for turbulent mixing in the ice-ocean boundary layer. Here we show that less than two-thirds of the turbulent kinetic energy (TKE) generated from mean flow shear under drifting sea ice is dissipated, and the remainder can be attributed to balancing stabilizing buoyancy fluxes. We deployed a high-resolution acoustic Doppler current profiler under an ice floe to estimate Reynolds stress, shear production and dissipation rate of TKE. At 0.75 m below the interface, dissipation rates from 1.5 × 10−9 to 4.2 × 10−7 m2 s−3, and shear production from 6.9×10−10 to 7.7×10−7 m2 s−3 were measured (5% to 95% percentiles), with shear production exceeding dissipation on average. The turbulent stress was largest during an event with ~ 9.2 h period oscillations in the upper ocean, consistent with tidally forced lee waves generated near steep topography. An overall estimate of the quadratic skin drag coefficient representative of the ice floe is CD0 = 7.0×10−4. We further identified three qualitative regimes of atmosphere-ice-ocean coupling in our observations: a high-frequency range (> 4 cycles per day, cpd) in which the ice acts like a rigid lid atop the ocean, an intermediate range, and a low-frequency range (< 0.8 cpd) where wind-driven ice drift determines the under-ice current. As the latter only contained half of the variance of the ice-relative flow, we emphasize that resolving sub-daily time scales is crucial in observing and modeling atmosphere-ice-ocean coupling.

© 2025 American Meteorological Society. This is an Author Accepted Manuscript distributed under the terms of the default AMS reuse license. For information regarding reuse and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: S. Reifenberg, simon.reifenberg@awi.de
Save