30 Nov 2021
30 Nov 2021
Status: a revised version of this preprint is currently under review for the journal TC.

On the evolution of an ice shelf melt channel at the base of Filchner Ice Shelf, from observations and viscoelastic modeling

Angelika Humbert1,2, Julia Christmann1, Hugh F. J. Corr3, Veit Helm1, Lea-Sophie Höyns1,4, Coen Hofstede1, Ralf Müller5,6, Niklas Neckel1, Keith W. Nicholls3, Timm Schultz5,6, Daniel Steinhage1, Michael Wolovick1, and Ole Zeising1,2 Angelika Humbert et al.
  • 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
  • 2University of Bremen, Department of Geosciences, Bremen, Germany
  • 3British Antarctic Survey, Natural Environment Research Council, Cambridge, UK
  • 4University of Bremen, Department of Mathematics and Computer Science, Bremen, Germany
  • 5Institute of Applied Mechanics, University of Kaiserslautern, Kaiserslautern, Germany
  • 6Division of Continuum Mechanics, Technical University of Darmstadt, Darmstadt, Germany

Abstract. Ice shelves play a key role in the stability of the Antarctic Ice Sheet due to their buttressing effect. A loss of buttressing as a result of increased basal melting or ice shelf disintegration will lead to increased ice discharge. Some ice shelves exhibit channels at the base that are not yet fully understood. In this study, we present in-situ melt rates of a channel which is up to 330 m high and located at the southern Filchner Ice Shelf. Maximum observed melt rates are 2.3 m a−1. Melt rates decline inside the channel along flow and turn into freezing 55 km downstream of the grounding line. While closer to the grounding line melt rates are higher within the channel than outside, this reverses further downstream. Comparing the evolution of this channel under present-day climate conditions over 250 years with its present geometry reveals a mismatch. This mismatch indicates melt rates two times higher were necessary over the past 250 years to form today's channel geometry. In contrast, forcing the model with present-day melt rates results in a closure of the channel, which contradicts observations. Time series of melt rate measurements show strong tidally-induced variability in vertical strain-rates. We found no evidence of seasonality, but discrete pulses of increased melting occurred throughout the measurement period. The type of melt channel in this study diminishes with distance from the grounding line and are hence not a destabilizing factor for ice shelves.

Angelika Humbert et al.

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-2021-350', Anonymous Referee #1, 14 Dec 2021
  • RC2: 'Comment on tc-2021-350', Anonymous Referee #2, 12 Jan 2022
  • EC1: 'Comment on tc-2021-350', Elisa Mantelli, 31 Jan 2022

Angelika Humbert et al.

Data sets

Raw data and derived products of the single-repeated pRES measurements, raw data of the ApRES time series Ole Zeising, Daniel Steinhage, Angelika Humbert

Surface accumulation data at pRES locations, processed GPS measurements Ole Zeising, Daniel Steinhage, Angelika Humbert

Model code and software

COM-ve-ld Julia Christmann, Ralf Müller, Angelika Humbert

Angelika Humbert et al.


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Short summary
Ice shelves are normally flat structures that fringe the Antarctic continent. At some locations they have channels incised into their underside. On Filchner Ice Shelf, such a channel is more than 50 km long and up to 330 m high. We conducted field measurements of basal melt rates and found a maximum of 2.3 m a−1. Simulations represent the geometry evolution of the channel reasonably well. There is no reason to assume that this type of melt channel is destabilizing ice shelves.