More than skin deep: sea surface temperature as a means of inferring
Atlantic Water variability on the southeast Greenland continental shelf
near Helheim Glacier
Abstract
Outlet glaciers account for almost half of the Greenland Ice Sheet’s
mass loss since 1990. Warming subsurface Atlantic Water (AW) has been
implicated in much of that loss, particularly along Greenland’s
southeastern coast. However, oceanographic observations are sparse prior
to the last decade, making it difficult to diagnose changes in AW
properties reaching the glaciers. Here, we investigate the use of sea
surface temperatures (SST) to quantify ocean temperature variability on
the continental shelf near Sermilik Fjord and Helheim Glacier. We find
that after removing the short-term, atmospheric-driven variability in
non-winter months, regional SSTs provide a reliable upper ocean
temperature record. In the trough region near Sermilik Fjord, the
adjusted SSTs correlate well with moored ocean measurements of the water
entering the fjord at depth and driving glacier melting. Using this
relationship, we reconstruct the AW variability on the shelf dating back
to 2000, eight years before the first mooring deployments. Seasonally,
AW reaches close to the fjord’s mouth in fall and winter and further
offshore in spring. Interannually, the AW temperatures in the trough do
not always track properties in the source waters of the Irminger
Current. Instead, the properties of the waters found at the fjord mouth
depend on both variations in the source AW and, also, in the Polar Water
that flows into the region from the Arctic Ocean. Satellite-derived
SSTs, although dependent on local oceanography, have the potential to
improve understanding around previously unanswered glacier-ocean
questions in areas surrounding Greenland and Antarctica.