Abstract:
The subtidal circulation of the southeast Greenland shelf is described using a set of highresolution
hydrographic and velocity transects occupied in summer 2004. The main
feature present is the East Greenland Coastal Current (EGCC), a low-salinity, highvelocity
jet with a wedge-shaped hydrographic structure characteristic of other surface
buoyancy-driven currents. The EGCC was observed along the entire Greenland shelf
south of Denmark Strait, while the transect north of the strait showed only a weak shelf
flow. This observation, combined with evidence from chemical tracer measurements that
imply the EGCC contains a significant Pacific Water signal, suggests that the EGCC is an
inner branch of the polar-origin East Greenland Current (EGC). A set of idealized
laboratory experiments on the interaction of a buoyant current with a submarine canyon
also supported this hypothesis, showing that for the observed range of oceanic
parameters, a buoyant current such as the EGC could exhibit both flow across the canyon
mouth or into the canyon itself, setting the stage for EGCC formation. Repeat sections
occupied at Cape Farewell between 1997 and 2004 show that the alongshelf wind stress
can also have a strong influence on the structure and strength of the EGCC and EGC on
timescales of 2-3 days. Accounting for the wind-induced effects, the volume transport of
the combined EGC/EGCC system is found to be roughly constant (~2 Sv) over the study
domain, from 68°N to Cape Farewell near 60°N. The corresponding freshwater transport
increases by roughly 60% over this distance (59 to 96 mSv, referenced to a salinity of
34.8). This trend is explained by constructing a simple freshwater budget of the
EGCC/EGC system that accounts for meltwater runoff, melting sea-ice and icebergs, and
net precipitation minus evaporation. Variability on interannual timescales is examined by
calculating the Pacific Water content in the EGC/EGCC from 1984-2004 in the vicinity
of Denmark Strait. The PW content is found to correlate significantly with the Arctic
Oscillation index, lagged by 9 years, suggesting that the Arctic Ocean circulation patterns
bring varying amounts of Pacific Water to the North Atlantic via the EGC/EGCC.
