New data on Progress Lake (Larsemann Hills, East Antarctica): Recently discovered subglacial part of the basin

In this paper, we present new data on the structure of the basin of Progress Lake (Larsemann Hills, East Antarctica). Located close to major logistic facilities of the polar stations and known for regular outburst floods, this lake was an object of interest in terms of ensuring safety of logistics operations. First reconnaissance survey carried out to the west of the known boarder of the Progress Lake showed the presence of a subglacial cavity filled with water. Based on the results of detailed ground-penetrating radar survey, electro-thermal drilling, water level observations, echo-sounding survey, and underwater photography, we show that this cavity acts as a subglacial part of the Progress Lake. We present the main morphometrical characteristics of Progress Lake calculated according to the new data: total area (203 600 m²), volume (1 806 300 m³), average depth (8.9 m), maximum depth (42.3 m), length (1160 m), maximum width (330 m). We also present an updated map of the Progress Lake and hydrological data (water level changes, water temperature, salinity, ion composition). The presence of perennial ice cover above the western part of the lake basin is explained by the specific microclimatic conditions of the area.