Shifts of the Recirculation Pathways in central Fram Strait drive
Atlantic Intermediate Water Variability on Northeast Greenland shelf
Abstract
Increased oceanic heat transport plays a key role in the accelerated
mass loss of Greenland’s marine-terminating glaciers. The melt rate of
major glaciers in Northeast Greenland (NEG) is controlled by ocean
variability, in particular warm Atlantic Intermediate Water (AIW), on
the continental shelf. A high-resolution configuration of the ocean
sea-ice model FESOM2.1 is validated at local and regional scales, and
used to investigate the drivers of AIW temperature variability on the
NEG shelf. The seasonal to decadal variability of the AIW is
characterised, featuring both pronounced interannual fluctuations and a
long-term warming trend. A major source of AIW is Atlantic Water (AW)
originating from the West Spitsbergen Current that recirculates in Fram
Strait. AW anomalies are advected westwards and partly control the AIW
temperatures on the shelf. Increased AIW temperatures are also connected
to more pronounced northern and middle branches of recirculating AW in
Fram Strait, and enhanced AW temperatures more regionally. This
strengthening of the pathways brings more and warmer AIW onto the
northern part of the NEG shelf. There, it circulates anti-cyclonically
and results in shelf-wide warming. Regional atmospheric forcing is
connected to the changes in the AW circulation regime. The strengthening
of the northern AW branches is likely caused by anticyclonic wind
anomalies over the Barents Sea that drive an enhanced northwards AW
transport in Fram Strait. Thus, controlled by a combination of both
upstream and regionally forced circulation conditions, the changes in
local AIW temperatures may also affect the oceanic heat transport
reaching the Arctic Ocean.