Firn aquifers in Antarctica: High-resolution mapping highlights predominance in the Antarctic Peninsula

Perennial firn aquifers in Greenland are crucial for meltwater storage, significantly influencing ice-sheet hydrology. In Antarctica, although firn aquifers have been identified in situ, a comprehensive continent-wide overview is currently lacking. Using an advanced methodology that integrates multiple datasets, our pioneering study presents a 2 x 2 km resolution assessment of firn aquifer distribution in Antarctica.
The focal point of our analysis is the creation of a heat map of firn aquifer locations across Antarctica. In contrast to prior studies, reliant on traditional binary evaluations of aquifer presence or absence, our method addresses the inherent uncertainty associated with firn aquifer extent and overcoming challenges posed by the vast and remote Antarctic environment.
We use a Monte Carlo method that exploits multiple datasets as input, spanning from 2017 to 2021. Data includes Sentinel-1, Advanced SCATterometer (ASCAT), and statistically downscaled output from the RACMO2.3p2 climate model. Each of these datasets highlights a particular property of firn aquifers.
Our high-resolution heat map reveals a concentration of firn aquifers across the Antarctic Peninsula (AP). Elevated probabilities are observed along its northern, northwest, and western coastlines, as well as on the Wilkins, Müller, and part of George VI ice shelves. Beyond the AP, aquifer evidence is sparse, with only a few locations exhibiting slightly elevated probabilities, such as on the Abbot, Shackleton, and Holmes ice shelves.
Validation of the methodology applied in Greenland using Operation IceBridge (OIB) data demonstrates a 91% correspondence with observed aquifers, firmly establishing the robustness of our approach.
Leveraging the sustained accessibility of freely available C-band and scatterometer observations, complemented by modeling data, our approach allows for ongoing long-term monitoring of aquifer conditions, proving crucial to explore the response of the Antarctic ice sheet to climate change.