Factors driving Supraglacial Lake variability on ice shelves in Dronning Maud Land, East Antarctica

Abstract

We have identified large spatiotemporal variability in the extent of supraglacial lakes on ice shelves in Dronning Maud Land, East Antarctica. While large lakes were found over Nivlisen and Roi Baudouin ice shelf areas, only small lakes were mapped over Fimbulisen and Muninisen. Preliminary analyses reveal a positive correlation between supraglacial lake extents (over specific ice shelves) and mean summer (December, January, February) temperatures and Positive Degree Days from ERA5. However, these correlations do not explain the large variability in overall Dronning Maud Land assessments. For instance, Fimbulisen area has the warmest summer temperatures and highest sum Positive Degree Days with very low lake extents. In contrast, the adjacent Nivlisen area with similar summer statistics has large spread of supraglacial lakes over the ice shelf area. We also identified that over specific melt years (e.g., 2016-2017, high lake extents; 2020-2021, low lake extents), all ice shelf areas with supraglacial lakes in Dronning Maud Land had relatively similar local lake extents, indicating the role of both regional and local factors influencing the ponding of meltwater. In this work, we attempt to identify the factors influencing melting and ponding in Dronning Maud Land. For this purpose, we use outputs from ERA5-Land and Modèle Régional Atmosphèrique (MAR) which have a higher spatial resolution (~10 km) than ERA5 (~31 km). At coarser resolutions climate models are deficient to capture localized processes that may have a crucial role in influencing surface melting and ponding – e.g., the katabatic winds. Outputs at higher resolutions may better constrain such small-scale phenomena and by using these datasets we may resolve the knowledge gap surrounding the controlling factors. Atmospheric factors in consideration are katabatic winds, cloudiness, precipitation, and albedo. Environmental factors such as blue ice, firn air content and surface topography will also be assessed to ascertain their influencing role. The results of this analysis will help in understanding the near-future evolution of supraglacial lakes on Dronning Maud Land and provide important insight into the future ice shelf stability in the region and also for improving estimates of the Antarctic ice sheet mass budget.