Summertime evaporation over two lakes in the Schirmacher oasis, East Antarctica

Abstract. The study quantified uncertainties in the bulk-aerodynamic method and combination formulas being applied in estimations of summertime evaporation over two lakes in the Schirmacher oasis, East Antarctica. The evaporation over the lakes was measured by the eddy-covariance (EC) technique during the austral summers (December–January) in 2017–2018 and 2019–2020. These direct measurements showed that summertime evaporation over two lakes varied from 0.3 to 5.0 mm d^–1. Depending on the ice cover presence, the average evaporation varied from 1.6 ± 0.1 mm d^–1 in December to 3.0 ± 0.2 mm d^–1 in January–February. In summer, the lakes were warmer than the ambient air, and the largest day-to-day variations in evaporation were associated with variations in the wind speed. The EC measurements were used as a reference for evaluating the uncertainties of the indirect methods. The bulk aerodynamic method gave the most accurate estimates of evaporation over two lakes (of 6–8 %), and this method showed acceptable skill scores (by two selected criteria) in estimation of the daily evaporation during the lakes' ice breaking-up and open water periods. This method is recommended for hydrological (lake water balance) applications required for operational (short term) decision making. Most of the combination formulas underestimated the summertime evaporation by 27–73 %.