Leveraging ICESat-2 altimetry for Antarctic subglacial lake identification, evolution, and basal properties

Funding Program: NASA Studies with ICESat-2
Start Date: 1 May 2021
End Date: 30 April 2024

Results from the Ice, Cloud, and land Elevation Satellite (ICESat), as well as aereogeophysical and ground-based surveys, revealed that the fast flowing portions of the Antarctic ice sheet are underlain by complex, dynamic hydrological systems. These timeevolving systems have the ability to control regional ice velocity, change grounding-line stability, and discharge freshwater and micronutrients to the sub-ice-shelf coastal environment. Hidden beneath 10s to 1000s of meters of ice, processes related to these enigmatic hydrological systems of interconnected lakes and streams are poorly understood, largely due to the limited temporal window of our active subglacial lake icesurface observational record from which we infer systematic subglacial hydrological dynamics, our simplified mechanical models of how subglacial lakes deform the overlying ice, and the lack of instrumentation to record downstream impacts. We propose to develop methods for retrieving dynamic ice surface-height changes from ICESat-2 laser altimetry that leverage the high spatial resolution and vertical precision of ICESat-2 data to better quantify Antarctic active subglacial lake location, magnitude, and stability from the coast to 88°S. Our work will couple our high precision retrieval of surfaceheight change to a newly developed, quantitative mechanical model to investigate and evaluate the relationship between surface-height change and properties of the subglacial environment, including subglacial water mass balance, fast versus slow drainage behaviors, and lakeshore migration.

Our proposed work will consist of two interrelated objectives:

1. Analyze ICESat-2 laser altimetry land-ice surface heights (the ATL06 data product), combined with ICESat and Operation IceBridge laser altimetry and CryoSat-2 radar altimetry, to extend and refine our multidecadal time series of dynamic hydrology systems beneath Antarctica, including generating high resolution, time-evolving maps of lake locations; and
2. Leverage the increased spatial resolution of ICESat-2 compared to previous altimeters to identify previously undetected areas of dynamic height change on the grounded ice sheet and apply novel statistical methods to quantify our confidence in the driver of these height anomalies.