Abstract
Abstract. Sea ice volume export through the Fram Strait represents an important freshwater input to the North Atlantic, which could in turn modulate the intensity of the thermohaline circulation. It also contributes significantly to variations in Arctic ice mass balance. We present the first estimates of winter sea ice volume export through the Fram Strait using CryoSat-2 sea ice thickness retrievals and three different ice drift products for the years 2010 to 2017. The monthly export varies between −21 and −540 km3. We find that ice drift variability is the main driver of annual and interannual ice volume export variability and that the interannual variations in the ice drift are driven by large-scale variability in the atmospheric circulation captured by the Arctic Oscillation and North Atlantic Oscillation indices. On shorter timescale, however, the seasonal cycle is also driven by the mean thickness of exported sea ice, typically peaking in March. Considering Arctic winter multi-year ice volume changes, 54 % of their variability can be explained by the variations in ice volume export through the Fram Strait.
Highlights
Variability in the Arctic sea ice export contributes significantly to the variations in surface salinity in the subpolar gyre, and in particular in the regions, where deep convection occurs, such as the Labrador and Greenland seas
We find that ice drift variability is the main driver of annual and interannual ice volume export variability and that the interannual variations in the ice drift are driven by large-scale variability in the atmospheric circulation captured by the Arctic Oscillation and North Atlantic Oscillation indices
We performed a detailed analysis of variability and important processes for the Arctic multi-year ice (MYI) mass balance
Summary
Variability in the Arctic sea ice export contributes significantly to the variations in surface salinity in the subpolar gyre, and in particular in the regions, where deep convection occurs, such as the Labrador and Greenland seas. A recent study by Ionita et al (2016) reports that persistent atmospheric blocking in winter leads to increased sea ice export through the Fram Strait, causing abrupt shifts in the Atlantic meridional overturning circulation variability. This might affect the climate over Europe. Arctic sea ice volume and related interannual variations have been investigated for the winter season (October–April) in various recent studies, using satellite altimetry (Tilling et al, 2015; Kwok and Cunningham, 2015; Ricker et al, 2017a). While first-year sea ice (FYI) volume reveals a distinct seasonal cycle between October and April due to thermodynamic growth and newly forming ice, multi-year sea ice (MYI) volume shows much smaller changes within the October–April period (Ricker et al, 2017a)
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