Preprints
https://doi.org/10.5194/tc-2021-203
https://doi.org/10.5194/tc-2021-203

  02 Aug 2021

02 Aug 2021

Review status: this preprint is currently under review for the journal TC.

Seasonal evolution of Antarctic supraglacial lakes in 2015–2021 and links to environmental controls

Mariel C. Dirscherl1, Andreas J. Dietz1, and Claudia Kuenzer1,2 Mariel C. Dirscherl et al.
  • 1German Remote Sensing Data Center (DFD), German Aerospace Center (DLR), Muenchener Strasse 20, 82234 Weßling, Germany
  • 2Institute of Geography and Geology, University Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany

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 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 enabling the delineation of also 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. Meltwater ponding on investigated East Antarctic ice shelves was far more variable with above average lake extents during most of melting seasons 2016–2019 and below average lake extents during 2020–2021. 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 varying air temperature, solar radiation, snowmelt, wind and precipitation, each at different time lags and directions and with strong local to regional discrepancies, as revealed through pixel-based correlation analysis. Southern Hemisphere atmospheric modes as well as the local glaciological setting including melt-albedo feedbacks and the firn air content were revealed to strongly influence the spatio-temporal evolution of supraglacial lakes as well as below or above average meltwater ponding despite variations in the strength of forcing. Recent increases of Antarctic Peninsula surface ponding point towards a further reduction of 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.

Mariel C. Dirscherl et al.

Status: open (until 03 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-203', Anonymous Referee #1, 14 Sep 2021 reply

Mariel C. Dirscherl et al.

Mariel C. Dirscherl et al.

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Short summary
We provide novel insight into the temporal evolution of supraglacial lakes across six major Antarctic ice shelves in 2015–2021. For Antarctic Peninsula ice shelves, we observe extensive meltwater ponding throughout summers 2019–2020 and 2020–2021. Over East Antarctica, lakes were widespread during 2016-2019 and at minimum in 2020–2021. We investigate environmental controls revealing lake ponding to be coupled to atmospheric modes, the near-surface climate and the local glaciological setting.