Tracing glacial meltwater from the Greenland Ice Sheet to the ocean
using gliders
Abstract
The Greenland Ice Sheet (GrIS) is experiencing significant mass loss and
freshwater discharge at glacier fronts. The freshwater input from
Greenland will impact the physical properties of adjacent coastal seas,
including important regions of deep water formation and contribute to
global sea level rise. However, the biogeochemical impact of increasing
freshwater discharge from the GrIS is less well constrained. Here, we
demonstrate the use of bio-optical sensors on ocean gliders to track
biogeochemical properties of meltwaters off Southwest Greenland. Our
results reveal that fresh, coastal waters, with an oxygen isotopic
composition characteristic of glacial meltwater, are distinguished by a
high optical backscatter and high levels of fluorescing dissolved
organic matter (FDOM), representative of the overall coloured dissolved
organic matter pool. Reconstructions of geostrophic velocities are used
to show that these particle and FDOM-enriched coastal waters cross the
strong boundary currents into the Labrador Sea. Meltwater input into the
Labrador Sea is likely driven by mesoscale processes, such as eddy
formation and local bathymetric steering, in addition to wind-driven
Ekman transport. Ocean gliders housing bio-optical sensors can provide
the high-resolution observations of both dissolved and particulate
glacially-derived material that are needed to understand meltwater
dispersal mechanisms and their sensitivity to future climatic change.