Abstract
Abstract. Supraglacial meltwater accumulation on ice shelves may have important implications for future sea level rise. Despite recent progress in the understanding of Antarctic surface hydrology, potential influences on ice shelf stability as well as links to environmental drivers remain poorly constrained. In this study, we employ state-of-the-art machine learning on Sentinel-1 synthetic aperture radar (SAR) and optical Sentinel-2 satellite imagery to provide new insight into the inter-annual and intra-annual evolution of surface hydrological features across six major Antarctic Peninsula and East Antarctic ice shelves. For the first time, we produce a high-resolution record of supraglacial lake extent dynamics for the period 2015–2021 at unprecedented 10 m spatial resolution and bi-weekly temporal scale. Through synergetic use of optical and SAR data, we obtain a more complete mapping record also enabling the delineation of buried lakes. Our results for Antarctic Peninsula ice shelves reveal below-average meltwater ponding during most of melting seasons 2015–2018 and above-average meltwater ponding throughout summer 2019–2020 and early 2020–2021 considering years 2015–2021 as a reference period. Meltwater ponding on investigated East Antarctic ice shelves was far more variable, with above-average lake extents during most 2016–2019 melting seasons and below-average lake extents during 2020–2021, considering the reference interval 2016–2021. This study is the first to investigate relationships with climate drivers both spatially and temporally including time lag analysis. The results indicate that supraglacial lake formation in 2015–2021 is coupled to the complex interplay of local, regional and large-scale environmental drivers with similar driving factors over both ice sheet regions. In particular, varying air temperature, solar radiation and wind conditions influenced supraglacial lake formation over all six ice shelves despite strong local to regional discrepancies, as revealed through pixel-based correlation analysis. Furthermore, regional climatic conditions were shown to be influenced by Southern Hemisphere atmospheric modes showing large-scale impacts on the spatio-temporal evolution of supraglacial lakes as well as on above- or below-average meltwater ponding with respect to the period 2015–2021. Finally, the local glaciological setting, including melt–albedo feedbacks and the firn air content, was revealed to strongly influence supraglacial lake distribution. Recent increases in Antarctic Peninsula surface ponding point towards a further reduction in the firn air content, implying an increased risk for ponding and hydrofracture. In addition, lateral meltwater transport was observed over both Antarctic regions with similar implications for future ice shelf stability.
Highlights
With accelerating global climate change, the Greenland and Antarctic ice sheets are exposed to increasing environmental pressure (Meredith et al, 2019)
Supraglacial lakes tend to form at low elevations and low surface slopes downstream of the grounding line
For the investigated Antarctic Peninsula ice shelves, our results reveal anomalously low supraglacial lake coverage during most 2015–2018 melting seasons and anomalously high lake coverage during 2019– 2020 and 2020–2021 summers considering the years 2015– 2021 as a reference period
Summary
With accelerating global climate change, the Greenland and Antarctic ice sheets are exposed to increasing environmental pressure (Meredith et al, 2019). Recent disintegration of Antarctic Peninsula (API) ice shelves was associated with atmospheric warming causing extensive meltwater ponding and hydrofracture to initiate ice shelf collapse (Banwell et al, 2013; Bell et al, 2018; Cook and Vaughan, 2010; Leeson et al, 2020; Rignot et al, 2004; Scambos et al, 2004). Ice shelf collapse leads to a reduction in buttressing, initiating glacier acceleration and causing API ice mass loss. With surface melting expected to double by 2050 (Trusel et al, 2015), Antarctic surface hydrological features will expand and likely contribute to future ice shelf instability and ice mass loss (Arthur et al, 2020b; Lai et al, 2020). Ice shelves that are structurally weakened by fractures and crevasses could be more vulnerable to hydrofracture (Lhermitte et al, 2020)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
