Temporal Evolution of Antarctic Surface Hydrology in 2015-2021 and Links to Environmental Drivers

Kurzfassung

Supraglacial meltwater ponding on ice sheets and ice shelves may have considerable impact on ice shelf stability, ice dynamics and global sea-level-rise. Recent disintegration of Antarctic Peninsula ice shelves and subsequent glacier acceleration was associated with atmospheric warming causing enhanced surface ponding to initiate hydrofracture. Apart from the risk of hydrofracture, enhanced surface melting may also lead to the connection of surface and basal hydrological systems or a modified albedo potentially contributing to ice dynamic change in the future. Despite recent progress in the understanding of Antarctic surface hydrology, detailed investigation of the seasonal evolution of supraglacial lake extents as well as links to environmental drivers are still lacking. In order to improve the understanding of present-day Antarctic surface hydrology, we apply state-of-the-art machine learning on Sentinel-1 SAR and optical Sentinel-2 satellite imagery for mapping of Antarctic supraglacial lake extent dynamics in 2015-2021. In particular, we produce bi-weekly supraglacial lake extent mappings for the period November to March of a melting season at unprecedented 10 m spatial resolution. We present results for selected Antarctic Peninsula ice shelves revealing below average lake coverage in 2015-2018 and above average lake coverage during summers 2019/2020 and 2020/2021. Supraglacial lake extents over selected East Antarctic ice shelves fluctuated more substantially with above average lake extents during most of 2016-2019 and below average lake extents throughout melting season 2020/2021. Statistical investigation of potential environmental drivers suggests a coupling between 2015-2021 supraglacial lake formation and the near-surface climate, the local glaciological setting as well as Southern Hemisphere atmospheric modes despite variations in the strength of forcing for each region. Further, our results imply supraglacial lake formation to respond to climate drivers at different time lags and with strong local to regional discrepancies.