Thermal regime and components of water balance of lakes in Antarctica at the Fildes peninsula and the Larsemann Hills

Abstract

Thermal regime and water balance components of 12 lakes located at two different parts of the Antarctic (the Fildes peninsula in the Maritime Antarctic and the Larsemann Hills in the continental Antarctica) were studied using the observations from three field campaigns in 2012–2014. The morphometric characteristics of the studied lakes were updated with GPS/echo-sounding surveys, and changes in the length, width and volume of the lakes were revealed in comparison with the previous surveys. The thermal regime of the lakes was also studied by modelling, applying the lake model FLake, which is widely used in different environmental applications but was tested for the first time in the Antarctic conditions. In contrast to boreal lakes, for lakes in Antarctica the modelling results by FLake appeared to be sensitive to the light extinction coefficient. According to simulations, all lakes were mixed down to the bottom for the whole summer; however, the reasons for this are different for shallow and deep lakes. The sensitivity of different methods to calculate evaporation, by the Dalton-type empirical equation and by the atmospheric surface layer block of FLake, was studied. For endorheic lakes, the sensitivity appeared to be large, up to 47% of the total seasonal water volume change, which assumes that FLake has the potential to be used in hydrological applications to calculate evaporation. Seasonal variations of the volume of the lakes in the continental Antarctica are larger than in the Maritime Antarctic. Usually, small and medium-sized lakes accumulate or redistribute water during the warm season. However, the systems of big lakes also release the stored water through the mechanism of abrupt jumps, which simultaneously cause the inflow into the sea of huge amounts of fresh water during short time intervals.