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Ocean Science An interactive open-access journal of the European Geosciences Union
Ocean Sci., 14, 127-138, 2018
https://doi.org/10.5194/os-14-127-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
21 Feb 2018
Observations of brine plumes below melting Arctic sea ice
Algot K. Peterson 1Geophysical Institute, University of Bergen, Bergen, Norway
2Bjerknes Centre for Climate Research, Bergen, Norway
Abstract. In sea ice, interconnected pockets and channels of brine are surrounded by fresh ice. Over time, brine is lost by gravity drainage and flushing. The timing of salt release and its interaction with the underlying water can impact subsequent sea ice melt. Turbulence measurements 1 m below melting sea ice north of Svalbard reveal anticorrelated heat and salt fluxes. From the observations, 131 salty plumes descending from the warm sea ice are identified, confirming previous observations from a Svalbard fjord. The plumes are likely triggered by oceanic heat through bottom melt. Calculated over a composite plume, oceanic heat and salt fluxes during the plumes account for 6 and 9 % of the total fluxes, respectively, while only lasting in total 0.5 % of the time. The observed salt flux accumulates to 7.6 kg m−2, indicating nearly full desalination of the ice. Bulk salinity reduction between two nearby ice cores agrees with accumulated salt fluxes to within a factor of 2. The increasing fraction of younger, more saline ice in the Arctic suggests an increase in desalination processes with the transition to the new Arctic.

Citation: Peterson, A. K.: Observations of brine plumes below melting Arctic sea ice, Ocean Sci., 14, 127-138, https://doi.org/10.5194/os-14-127-2018, 2018.
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Short summary
This study presents observations of brine descending from melting Arctic sea ice. The brine passed an under-ice turbulence instrument in plumes and was associated with very high heat fluxes. The salt flux indicates that the melting sea ice lost most of its salt content during the observations. The observations provide evidence of a desalination process not previously reported from drifting Arctic sea ice and is an important contribution to understanding ice–ocean interaction during melt.
This study presents observations of brine descending from melting Arctic sea ice. The brine...
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