The Arctic and subarctic oceans exhibit distinct decadal variations in
freshwater and heat content. We describe freshwater and heat budgets
with the ECCOv4 reanalysis product and compare budget variability and
mechanisms within the subpolar North Atlantic Ocean, Nordic Seas and
Labrador Sea from 1992 to 2015. For all regions, changes in freshwater
content are largely anti-correlated with changes in heat content. Since
1995, the subpolar North Atlantic Ocean has undergone a decade of
warming and salinification followed by ongoing cooling and freshening.
The recent increase in freshwater content and the reduction in heat in
the subpolar North Atlantic can largely be attributed to anomalous
circulation of mean salinity and temperature, respectively. Interannual
variability in heat and freshwater mostly corresponds to boundary fluxes
from the subtropics. Meanwhile the Nordic Seas have undergone an overall
warming and salinification from the mid-1990s to 2015. Salinification is
primarily driven by reduced sea ice flux through Fram Strait, while
warming is due to changes in both sea surface heating and advective
flux. In the last five years, Labrador Sea freshwater convergence
remained unchanged, as increased inflow via the Baffin Island Current is
balanced by increased outflow via the Labrador Current. Hence the
observed freshening of the Arctic Ocean is expected to be an
increasingly important source of future freshwater increases in the
subpolar North Atlantic. This stands in contrast to variability in
freshwater flux from the subtropical North Atlantic, which is associated
with variability in the Atlantic Meridional Overturning Circulation.