Intrusions of Atlantic Water cause basal melting of Greenlands marine terminating
glaciers and ice shelves such as that of Petermann Glacier, in northwest
Greenland. The fate of the resulting glacial meltwater is largely unknown.
It is investigated here, using hydrographic observations collected during
a research cruise in Petermann Fjord and adjacent Nares Strait on board
I/B Oden in August 2015. A three end-member mixing method provides the
concentration of Petermann ice shelf meltwater. Meltwater from Petermann
is found in all of the casts in adjacent Nares Strait, with highest concentration
along the Greenland coast in the direction of Kelvin wave phase propagation.
The meltwater from Petermann mostly flows out on the northeast side of the
fjord as a baroclinic boundary current, with the depth of maximum meltwater
concentrations approximately 150 m and shoaling along its pathway. At the
outer sill, which separates the fjord from the ambient ocean, approximately
0.3 mSv of basal meltwater leaves the fjord at depths between 100 and 300 m.
The total geostrophic heat and freshwater fluxes close to the glacier’s terminus
in August 2015 were similar to those estimated in August 2009, before the
two major calving events that reduced the length of Petermann’s ice tongue
by nearly a third, and despite warmer inflowing Atlantic Water. These results
provide a baseline, but also highlight what is needed to assess properly
the impact on ocean circulation and sea level of Greenland’s mass loss as the
Atlantic Water warms up