The Deutsche Forschungsgemeinschaft (DFG), a research-funding organization, has granted EOC scientist Dr. Mariel Dirscherl the Bernd Rendel Geoscience Award 2022 for her doctoral dissertation on supraglacial lakes on the Antarctic ice sheet. This award is bestowed on only two scientists annually.
Her doctoral dissertation combines earth observation, machine learning, local, regional and wide-area environmental parameters, and models of the physical atmosphere. The jury also acknowledged Frau Dirscherl‘s overall science performance and interdisciplinary research at the interface between remote sensing and cryosphere research.
Left to right: Prof. Friedhelm von Blanckenburg (GFZ Potsdam/FU Berlin), Dr. Mariel Dirscherl (DLR), Dr. Ismene Seeberg-Elverfeldt (DFG); ©Raphael Fuhrmann/RF-Fotografie
With the help of artificial intelligence methodologies Dr Dirscherl developed an algorithm to achieve automated identification of supraglacial lakes in optical satellite image data (Sentinel-2) and radar measurements (Sentinel-1). This made it possible for the first time to monitor the seasonal dynamics of supraglacial lakes in several ice shelf regions of the Antarctic during the years 2015 - 2021.
Supraglacial lakes result from melting processes on the ice surface and they can drain suddenly through cracks in the glacier or on the ice shelf. For that reason it is essential to monitor them at short temporal intervals. Meltwater penetration can, for example, lead to the collapse of shelf ice and it can accelerate the downward flow of inland ice. Until recently large parts of the Antarctic were considered to be too cold for supraglacial lakes to exist there.
Sentinel-2 image showing supraglacial lakes on the Riiser-Larsen ice shelf in Eastern Antarctica
The investigation revealed that during the melting seasons taking place between 2015/2016 and 2018/2019 only relatively few small-scale supraglacial lakes could be detected on the Antarctic Peninsula. But then in January 2020 and 2021 at the height of the melting season considerably more lakes appeared than in the years before. In the shelf ice regions of Eastern Antarctica the situation was different. Here there were more supraglacial lakes during the summer melting seasons 2016/2017 to 2019/2020, while their number strongly decreased in the 2020/2021 melting season.
Sentinel-1/-2 basierte Klassifikation supraglazialer Seen über den Schelfeis-Regionen im Bellingshausen Sea Sector der Antarktischen Halbinsel
Supraglacial lakes on the George VI ice shelf, Antarctic Peninsula (Sentinel-2 false-colour composite with an overlay based on a Sentinel-1/-2 classification of supraglacial lakes in January 2020)
Statistical correlation of the results with seasonal climate data and annual data on atmospheric dynamics was undertaken to determine the factors influencing the formation of meltwater lakes. In both of the Antarctic regions investigated it could be shown that the complex interactions of local environmental factors (such as firn air content, albedo, topography), regional climate factors (like temperature, solar insolation, wind) and large-scale atmospheric circulations (such as the Southern Annular Mode and the Amundsen Sea Low) favour the emergence of supraglacial lakes. The results also suggest that the number and extent of supraglacial lakes will greatly increase in the Antarctic because of climate change. This in turn significantly influences the stability of ice shelf surfaces, the future loss of ice mass, and the global ocean level increase. Up until now the influence of supraglacial lakes has, however, been inadequately considered in forecasting models.