| Summary: | <p>By enforcing a strong stratification at the ocean surface, freshwater is a key determiner of the physical and biogeochemical dynamics of the Arctic Ocean. In addition, fluxes of Arctic freshwater to the Atlantic have the potential to impact the Atlantic Meridional Overturning Circulation, with global implications for climate. The Arctic Ocean is understood to be freshening, but our grasp of its freshwater variability---in time and space---is hampered by the short duration and sparsity of observations.</p>
<p>We seek to explore the causes of recent changes in Arctic liquid freshwater content (FWC) and interpret the processes underpinning its variability on Arctic-wide and regional scales. We focus on the interactions between wind patterns, sea ice dynamics and thermodynamics, and FWC.</p>
<p>Through the application of linear response theory to a suite of coupled climate models, we demonstrate that Arctic FWC has a decadal memory of wind forcing, and that recent changes in FWC can be largely explained by variability in the leading modes of atmospheric circulation. Using forced ice-ocean model experiments, we show that---via dynamic thinning of sea ice in the interior Arctic basins---Fram Strait sea ice export can impact seasonal ice growth and melt, in a manner sensitive to wind forcing and ice dynamics. By constructing a linear model using data from a large ensemble of climate model simulations, we determine controls on forced changes in ice production in the Kara and Laptev seas with anthropogenic climate change, and highlight a pivotal role for September sea ice area changes. Relying on a series of coordinated model experiments, we demonstrate that sea ice import into the Beaufort gyre influences wind-driven FWC accumulation/flushing.</p>
<p>Our results emphasise the central importance of winds in controlling Arctic FWC variability, and elucidate significant roles for wind-driven sea ice dynamics in affecting liquid FWC via the hermodynamic growth and melt of sea ice.</p>
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