Preprints
https://doi.org/10.5194/tc-2023-4
https://doi.org/10.5194/tc-2023-4
 
23 Jan 2023
23 Jan 2023
Status: this preprint is currently under review for the journal TC.

Recent Evolution of Supraglacial Lakes on ice shelves in Dronning Maud Land, East Antarctica

Anirudha Mahagaonkar1,2, Geir Moholdt1, and Thomas V. Schuler2 Anirudha Mahagaonkar et al.
  • 1Norwegian Polar Institute, Tromsø, 9296, Norway
  • 2Department of Geosciences, University of Oslo, Oslo, 0315, Norway

Abstract. Accumulation of meltwater on the surface of ice shelves can have severe impacts on the ice sheet – ice shelf stability regime. Meltwater ponding on ice shelves can cause firn air depletion, flexure, hydrofracture and collapse of shelves that could further lead to increased ice-sheet discharge and sea level rise. Despite recent progress in the mapping of supraglacial lakes around Antarctica, there is still limited understanding of their dynamics, climatic and environmental controls, and their role in the Antarctic ice sheet mass budget. In this study, we track the seasonal and interannual evolution of supraglacial lakes on ice shelves in Dronning Maud Land in East Antarctica. The assessment employs an automatized band-thresholding approach to examine nearly 2500 Landsat-8 and Sentinel-2 scenes captured between November and March from 2014 to 2021. Large networks of supraglacial lakes and streams were identified over the ice shelves Riiser Larsen, Nivlisen and Roi Baudouin, whereas other ice shelves had only smaller areas with isolated ponds (Fimbulisen and Muninisen) or no significant meltwater lakes at all. Despite large interannual variations in surface ponding, in specific melt years the relative extents were mostly consistent between different ice-shelf regions. The peak extents of supraglacial lakes typically occurred in mid-to-late January and varied from 38.19 ± 29.53 km2 in the low melt-year 2020–2021 to 809.37 ± 206.74 km2 in the high melt-year 2016–2017, corresponding to water volumes of 0.03 ± 0.02 km3 and 0.67 ± 0.16 km3 respectively. Comparison with positive degree days and seasonal temperatures shows considerable correlation with maximum lake extent for some ice shelves, but in total, it cannot explain the large differences in magnitudes of surface ponding over different ice shelves. For instance, melt extents of Fimbulisen and Nivlisen that lie next to each other differ by two orders of magnitude. Our assessments provide important insights into surface hydrology over the region and will be helpful to further constrain the different processes that control the evolution of supraglacial meltwater systems in Dronning Maud Land.

Anirudha Mahagaonkar et al.

Status: open (until 20 Mar 2023)

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Anirudha Mahagaonkar et al.

Anirudha Mahagaonkar et al.

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Short summary
Surface meltwater lakes along the margins of the Antarctic Ice Sheet can be important for ice shelf dynamics and stability. We used optical satellite imagery to study seasonal evolution of meltwater lakes in Dronning Maud Land. We found large interannual variability in lake extents, but with consistent seasonal patterns. Although correlation with summer air temperature was strong locally, other climatic and environmental factors need to be considered to explain the large regional variability.