Preprints
https://doi.org/10.5194/tc-2023-157
https://doi.org/10.5194/tc-2023-157
23 Oct 2023
 | 23 Oct 2023
Status: this preprint is currently under review for the journal TC.

Accumulation by avalanches as significant contributor to the mass balance of a High Arctic mountain glacier

Bernhard Hynek, Daniel Binder, Michele Citterio, Signe Hillerup Larsen, Jakob Abermann, Geert Verhoeven, Elke Ludewig, and Wolfgang Schöner

Abstract. Greenland's peripheral glaciers are losing mass at an accelerated rate and are contributing significantly to sea level rise, but only a few direct observations are available. Here, we use the unique combination of high-resolution remote sensing data and direct mass balance observations to separate and quantify the contribution of a singular avalanche event to the mass balance of Freya Glacier (74.38° N, 20.82 W), a small (5.5 km², 2021) mountain glacier in Northeast Greenland. Elevation changes calculated from repeated photogrammetric surveys on 11th–18th August 2013 and on 28th–31st July 2021 range from -11 m to 18 m, with a glacier-wide mean of 1.56 + 0.10 m (0.85 + 0.20 m w.e.). Somewhat surprisingly, the geodetic mass balance over the full period of 8 years (2013/14–2020/21) is slighly positive, (0.25 + 0.21 m w.e.). A main imprint of the near decadal mass balance stems from the exceptional (2.5 standard deviations above average) winter mass balance of 2017/18 with 1.85 + 0.05 m w.e., when in addition to above average precipitation, snow avalanches affected more than one third of the glacier surface and contributed at least 0.31 m w.e. (17 %) to the total winter mass balance of 2017/18. We estimate the contribution of avalanches to the accumulated mass balance 2013/14–2020/21 as 0.55 m w.e. Without this avalanche event the 8-year mass balance would have been slightly negative, -0.30 m w.e. instead of 0.25 m w.e. Due to a gap in valid observations caused by high accumulation rates and the COVID-19 pandemic the recently reported glacier-wide annual mass balance values now turn out to have a negative bias and demand a thorough reanalysis. Finally, we speculate that the projected future warming increases the likelihood of extreme snowfall events for individual years and thus, may increase the contribution of snow avalanches to the mass balance of mountain glaciers in NE Greenland. 

Bernhard Hynek, Daniel Binder, Michele Citterio, Signe Hillerup Larsen, Jakob Abermann, Geert Verhoeven, Elke Ludewig, and Wolfgang Schöner

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2023-157', Anonymous Referee #1, 30 Oct 2023
    • AC1: 'Reply on RC1', Bernhard Hynek, 18 Jan 2024
  • RC2: 'Comment on tc-2023-157', Anonymous Referee #2, 16 Nov 2023
    • AC2: 'Reply on RC2', Bernhard Hynek, 18 Jan 2024
Bernhard Hynek, Daniel Binder, Michele Citterio, Signe Hillerup Larsen, Jakob Abermann, Geert Verhoeven, Elke Ludewig, and Wolfgang Schöner
Bernhard Hynek, Daniel Binder, Michele Citterio, Signe Hillerup Larsen, Jakob Abermann, Geert Verhoeven, Elke Ludewig, and Wolfgang Schöner

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Short summary
A strong avalanche event in winter 2018 caused thick snow deposits on Freya Glacier, a mountain glacier in Northeast Greenland. The avalanche deposits led to positive elevation changes during the study period 2013–2021 and altered the mass balance of the glacier significantly. The eight year mass balance was positive, it would have been negative without avalanches. The contribution from snow avalanches might become more important with rising temperatures in the Arctic.