Sea Ice Meltwater in the Beaufort Gyre: A Comprehensive Analysis Using
Sea Surface Salinity Data from SMOS
Abstract
Arctic sea ice is retreating, thinning, and exhibiting increased
mobility. In the Beaufort Gyre (BG), liquid freshwater content (FWC) has
increased by 40\% in the last two decades, with sea ice
melting being a primary contributor. This study utilizes satellite
observations of sea surface salinity (SSS) and sea ice concentration,
along with model-based sea ice thickness from 2011 to 2019. The aim is
to investigate the sea ice-SSS relationship at different scales in the
Arctic and understand the sea-ice meltwater dynamics in the BG. Our
findings reveal a strong synchrony and positive correlation between sea
ice area and SSS in the Arctic Ocean. In September, when the BG exhibits
the largest ice-free ocean surface, a noticeable release of freshwater
from sea ice melting occurs, a phenomenon not accurately reproduced by
the models. The SMOS (Soil Moisture and Ocean Salinity) mission proves
valuable in detecting meltwater lenses (MWL) originating from sea ice
melting. These MWLs exhibit mean SSS ranging from 19 psu at the begining
of sea ice retreat to 25 psu before sea ice formation. Wind-driven
anticyclonic eddies can trap MWLs, preserving the freshest SSS imprints
on the sea surface for up to 10 days. Furthermore, events of sea surface
salinification following sea ice formation suggest that SMOS SSS might
be capturing information on brine rejection. The daily evolution of sea
ice-SSS within the MWLs demonstrates a tight correlation between both
variables after sea ice melting and just before sea ice formation,
indicating a transient period in between.