Drivers of surface salinity changes in the Greenland-Iceland Seas on
seasonal and interannual time scales - a climate model study
Abstract
The Arctic climate is changing dramatically, especially in terms of sea
ice loss, with potentially large downstream impacts on the Nordic Seas
and the North Atlantic Ocean. The East Greenland Current (EGC)
transports substantial amounts of freshwater (in liquid and solid
states) southward along the east Greenland continental slope. To
increase our understanding of the drivers of surface salinity changes in
the interior Nordic Seas, we investigate the diversion of freshwater
from the EGC into the Nordic Seas. To this end, we analyse the outcomes
of an ocean model hindcast for the period 1973-2004 with a horizontal
resolution of 0.25 degree. We find that sea ice contributes large
amounts of freshwater to the interior Nordic Seas. On an interannual
time scale, this sea ice diversion has a high and significant
correlation with surface salinity in the Greenland and Iceland Seas
(correlation < -0.7). On a seasonal time scale, the model
hindcast and observations demonstrate a clear signal in surface
salinity: a lateral migration of the Polar Front position occurring
along all of east Greenland. In the model hindcast, these lateral shifts
in the front are consistent with seasonal changes in the westward
wind-driven Ekman transport. Thus, this climate model study indicates
that there are two main causes of seasonal and interannual surface
salinity changes; wind-driven Ekman transport and sea ice diversion from
the EGC, respectively.