Satellite investigations of glacial meltwater plumes

Calving at marine terminating glaciers accounts for at least 40 % of mass loss from the Greenland ice sheet, the current largest land ice sea level rise (SLR) contributor. Research suggests that glacier meltwater plumes play an important role in glacier calving front retreat and so studying their extent (2D and 3D) and temporal and spatial variability is critical for estimating potential SLR.

This work presents the novel use of satellite synthetic aperture radar (SAR) to study glacial meltwater plume extent and compares this approach to the more standard use of cloud and light-limited multispectral data for observations of plume extent. SAR data have often been used in oceanography to isolate ocean fronts, large-scale upwelling and estuarine plumes but have not thus far been used for studying glacial meltwater plumes. A SAR intensity image is retrieved from the backscatter signal which is a function of wind, wave and current interactions on a water surface, therefore, any ocean or river features which modify these have the potential to be identified within the SAR image. Higher resolution SAR data have more recently become available providing the opportunity to study meltwater plumes which present as an upwelling in the glacier fjord or lake in front of the glacier.

An initial study location of Breiðamerkurjökull glacier and Jökulsárlón proglacial lake, in Iceland, was chosen for the study which will involve fieldwork in 2022 to allow 3D analysis of plumes. This location is logistically easier and less expensive than Greenland yet provides an ideal analogue for study of Greenland glacier meltwater plumes in fjord-ocean systems. This is due to the connection of Jökulsárlón glacial lake water with the North Atlantic Ocean via a channel through which all tidal and residual flows in and out of the lake occur (Brandon et al., 2017) much like a glacier-fjord system in Greenland. Breiðamerkurjökull glacier calving front terminates in Jökulsárlón just like a marine terminating glacier in Greenland terminates in a fjord. Here initial results from quantifying the 2D extent of surface plumes using SAR are presented.