In-Situ Observations of a Subglacial Outflow Plume in a Greenland Fjord

Abstract:

We present oceanographic observations collected in and
immediately outside of a buoyant, fresh, sediment-laden
subglacial outflow plume rising up the marine-terminating front
of Sarqardleq Glacier, Greenland (68.9 N, 50.4 W). Subglacial
outflow plumes, associated with the discharge at depth of
upstream glacial surface melt, entrain the relatively warm fjord
waters and are correlated with enhanced submarine melt and
increased calving. Few in-situ observations exist due to the
challenges of making measurements at the calving front of
glaciers. Our data were collected using a small boat, a
helicopter, and a JetYak (a remote-controlled jet-ski-powered
kayak). Temperature and salinity profiles in, around, and far
from the plume are used to described its oceanographic
properties, spatial extent, and temporal variability. This plume
rises vertically up the ice front expanding laterally and away
from the ice, over-shoots its stable isopycnal and reaches the
surface. Its surface expression is identified by colder, saltier,
sediment-laden water flowing at ~5 m/s away from the ice
face. Within ~300 m from the ice it submerges as it seeks buoyant
stability.