Preprints
https://doi.org/10.5194/egusphere-2023-2874
https://doi.org/10.5194/egusphere-2023-2874
11 Jan 2024
 | 11 Jan 2024

Change in grounding line location on the Antarctic Peninsula measured using a tidal motion offset correlation method

Benjamin J. Wallis, Anna E. Hogg, Yikai Zhu, and Andrew Hooper

Abstract. The grounding line position of glaciers and ice shelves is an essential observation for the study of the Earth’s ice sheets. However, in some locations, such as the Antarctic Peninsula, where many grounding lines have not been mapped since the 1990s, remote sensing of grounding line position remains challenging. Here we present a tidal motion offset correlation (TMOC) method for measuring the grounding line position of tidewater glaciers and ice shelves, based on the correlation between tide amplitude and synthetic aperture radar offset tracking measurements. We apply this method to the Antarctic Peninsula Ice Sheet to automatically delineate a new grounding line position for 2019–2020, with near complete coverage along 9,300 km of coastline, updating the 20-year-old record. A comparison of the TMOC grounding line to contemporaneous interferometrically-measured grounding line position shows the method has a mean seaward offset compared to interferometry of 185 m and a standard deviation of 295 m. Our results show that over the last 24 years there has been grounding line retreat at a number of fast flowing ice streams on the Antarctic Peninsula, with the most retreat concentrated in the north-eastern sector, where grounding lines have retreated following the collapse of ice shelves. We observe a maximum grounding line retreat since 1996 of 16.3 km on Hektoria Glacier, with other notable glaciers retreating by 9.3 km, 9.1 km, and 3.6 km respectively. Our results document dynamic change on Antarctic Peninsula glaciers and show the importance of using an updated grounding line location to delineate the boundary between floating and grounded ice.

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Benjamin J. Wallis, Anna E. Hogg, Yikai Zhu, and Andrew Hooper

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2874', Anonymous Referee #1, 20 Jan 2024
    • AC1: 'Reply on RC2', Benjamin Wallis, 29 Mar 2024
  • RC2: 'Comment on egusphere-2023-2874', Anonymous Referee #2, 24 Jan 2024
    • AC1: 'Reply on RC2', Benjamin Wallis, 29 Mar 2024
  • RC3: 'Comment on egusphere-2023-2874', Anonymous Referee #3, 30 Jan 2024
    • AC1: 'Reply on RC2', Benjamin Wallis, 29 Mar 2024
  • RC4: 'Comment on egusphere-2023-2874', Anonymous Referee #1, 03 Feb 2024
    • AC1: 'Reply on RC2', Benjamin Wallis, 29 Mar 2024
Benjamin J. Wallis, Anna E. Hogg, Yikai Zhu, and Andrew Hooper

Data sets

Reviewer Assets for "Change in grounding line location on the Antarctic Peninsula measured using a tidal motion offset correlation method" by Wallis et al. 2023 Benjamin J. Wallis, Anna E. Hogg, Yikai Zhu, and Andrew Hooper https://doi.org/10.5281/zenodo.10233476

Benjamin J. Wallis, Anna E. Hogg, Yikai Zhu, and Andrew Hooper

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Short summary
The grounding line, where ice begins to float, is an essential variable to understand ice dynamics, but in some locations it can be difficult to measure. Using satellite data and a new method, Wallis et al. measure the grounding line position of glaciers and ice shelves in the Antarctic Peninsula and find retreats of up to 16.3 km have occurred since the last time measurements were made in 1990s.