Observations of brine plumes below Arctic sea ice
Peterson, Algot Kristoffer
- Publisher: European Geosciences Union
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 anti-correlated 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 agree with accumulated salt fluxes to within factor of two. The
increasing fraction of younger, more saline ice in the Arctic suggests an increase in desalination processes with the transition
to the ’new Arctic’.