New Active Antarctic Subglacial Lakes using 10 years of CryoSat-2 Altimetry

Abstract

Subglacial lakes beneath the Antarctic Ice Sheet were first identified using airborne radio-echo sounding (RES) surveys from the 1960s. In Antarctica, 20% of 675 currently identified subglacial lakes are “active,” exhibiting draining and filling behaviour as water flows through them. Clusters of active subglacial lakes often form in networks, connected by subglacial hydrological pathways which enable transfer of water between lakes themselves. Signals of this hydrological activity at the ice base can be detected in height changes at the ice sheet surface. Despite efforts to observe and understand this component of ice sheet mechanics, triggers of lake drainage events, in addition to drainage mechanisms and their variability are currently unresolved. An ongoing challenge lies in accurately identifying the location and extent of subglacial lakes. We present a new dataset of locations and boundaries for over 100 newly identified subglacial lakes in Antarctica. Using 10 years of CryoSat-2 swath-processed altimetry data, from 2011-2021, we identify localised regions of ice surface uplift and subsidence associated with subglacial lake filling and draining cycles. We use a new method to manually delineate subglacial lake maximum extent boundaries for individual filling and drainage periods. These results provide insights into new areas of subglacial hydrological activity in Antarctica and their evolution over time, which are vital to resolve in order to understand their impacts on Antarctic Ice Sheet stability.