Abstract
Warm, subtropical-originating Atlantic water
(AW) has been identified as a primary driver of mass loss
across the marine sectors of the Greenland Ice Sheet (GrIS),
yet the specific processes by which this water mass interacts
with and erodes the calving front of tidewater glaciers
is frequently modelled and much speculated upon but remains
largely unobserved.We present a suite of fjord salinity,
temperature, turbidity versus depth casts along with glacial
runoff estimation from Rink and Store glaciers, two major
marine outlets draining the western sector of the GrIS during
2009 and 2010. We characterise the main water bodies
present and interpret their interaction with their respective
calving fronts. We identify two distinct processes of ice–
ocean interaction which have distinct spatial and temporal
footprints: (1) homogenous free convective melting which
occurs across the calving front where AW is in direct contact
with the ice mass, and (2) localised upwelling-driven
melt by turbulent subglacial runoff mixing with fjord water
which occurs at distinct injection points across the calving
front. Throughout the study, AW at 2.8±0.2 C was
consistently observed in contact with both glaciers below
450m depth, yielding homogenous, free convective submarine
melting up to 200m depth. Above this bottom layer,
multiple interactions are identified, primarily controlled by
the rate of subglacial fresh-water discharge which results in
localised and discrete upwelling plumes. In the record melt
year of 2010, the Store Glacier calving face was dominated
by these runoff-driven plumes which led to a highly crenulated
frontal geometry characterised by large embayments at
the subglacial portals separated by headlands which are dominated
by calving. Rink Glacier, which is significantly deeper
than Store has a larger proportion of its submerged calving
face exposed to AW, which results in a uniform, relatively
flat overall frontal geometry.
(AW) has been identified as a primary driver of mass loss
across the marine sectors of the Greenland Ice Sheet (GrIS),
yet the specific processes by which this water mass interacts
with and erodes the calving front of tidewater glaciers
is frequently modelled and much speculated upon but remains
largely unobserved.We present a suite of fjord salinity,
temperature, turbidity versus depth casts along with glacial
runoff estimation from Rink and Store glaciers, two major
marine outlets draining the western sector of the GrIS during
2009 and 2010. We characterise the main water bodies
present and interpret their interaction with their respective
calving fronts. We identify two distinct processes of ice–
ocean interaction which have distinct spatial and temporal
footprints: (1) homogenous free convective melting which
occurs across the calving front where AW is in direct contact
with the ice mass, and (2) localised upwelling-driven
melt by turbulent subglacial runoff mixing with fjord water
which occurs at distinct injection points across the calving
front. Throughout the study, AW at 2.8±0.2 C was
consistently observed in contact with both glaciers below
450m depth, yielding homogenous, free convective submarine
melting up to 200m depth. Above this bottom layer,
multiple interactions are identified, primarily controlled by
the rate of subglacial fresh-water discharge which results in
localised and discrete upwelling plumes. In the record melt
year of 2010, the Store Glacier calving face was dominated
by these runoff-driven plumes which led to a highly crenulated
frontal geometry characterised by large embayments at
the subglacial portals separated by headlands which are dominated
by calving. Rink Glacier, which is significantly deeper
than Store has a larger proportion of its submerged calving
face exposed to AW, which results in a uniform, relatively
flat overall frontal geometry.
| Original language | English |
|---|---|
| Pages (from-to) | 1457-1468 |
| Journal | The Cryosphere Discussions |
| Volume | 8 |
| DOIs | |
| Publication status | Published - 2014 |
