Assessing the subglacial lake coverage of Antarctica

The existences of water at the base of the Antarctic Ice Sheet has been proven by the observation of several hundred subglacial lakes within the last five decades. They accumulate basal melt water from their upstream catchment areas and release it continuously or in surges towards other downstream located subglacial lakes and eventually to the ocean. Both subglacial lakes and basal water streams are recognized to decrease traction at the ice base and thus have a great impact on ice dynamics. However, the total extent of Antarctic subglacial lakes is still unknown, since particularly the detection of smaller lakes depends on in situ survey campaigns. We approach this question by combining modeling and remote-sensing strategies. Following Shreve's hydraulic potential equation, we simulate possible lake locations and can thus recall the majority of the currently observed lakes. Additionally, we find many new and so far unexplored possible lake locations. In order to validate these predictions, we analyze ice-penetrating radar profiles from our radio-echo sounding flights of the entire last decade in Dronning Maud Land. This leads to the identification of 31 new subglacial lakes. Based on these findings, we estimate the total number of Antarctic subglacial lakes to be about 1300, a factor of three more than what has been discovered so far. Their overall extent is assessed to cover about 0.6 % of the Antarctic ice-bed interface. Respective to assessments of the current inventory, we find that only about 30 % of all Antarctic subglacial lakes and about 65 % of the total estimated lake-covered area are discovered at present