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Basal melting and oceanic observations beneath Fimbulisen, East Antarctica
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  • Katrin Lindbäck,
  • Elin Darelius,
  • Geir Moholdt,
  • Irena Vankova,
  • Tore Hattermann,
  • Julius Lauber,
  • Laura de Steur
Katrin Lindbäck
Mittuniversitetet

Corresponding Author:[email protected]

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Elin Darelius
University of Bergen
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Geir Moholdt
Norwegian Polar Institute
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Irena Vankova
Los Alamos National Laboratory
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Tore Hattermann
Norwegian Polar Institute
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Julius Lauber
Norwegian Polar Institute
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Laura de Steur
Norwegian Polar Institute
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Abstract

Basal melting of ice shelves is fundamental to Antarctic Ice Sheet mass loss, yet direct observations are sparse. We present the first melt record (2017 to 2021) from a phase-sensitive radar at Fimbulisen, East Antarctica, one of the fastest flowing ice shelves in Dronning Maud Land. The observed long-term mean ablation below the central part of the ice shelf was 1.0 ±0.4 m yr–1, marked by substantial sub-weekly variability ranging from 0.3 to 3.8 m yr–1. 36-h filtered fluctuations in basal melt exhibit a close alignment with ocean velocity, revealing shear-driven turbulent heat transfer as the predominant driver of melt variability at sub-weekly to monthly timescale. Seasonally, basal melt rates are highest in the austral summer, when ocean temperature is higher. Our observed in-situ melt rates show threefold lower amplitudes and a 3-month delay in seasonality compared to satellite-derived melt rates, however, the long-term multi-year mean is of similar magnitude (1.0 m yr–1 vs 0.8 m yr–1). Our detailed ice–ocean observations provide essential validation data for remote sensing and numerical models aiming to measure and project ice-shelf response to ocean forcing. In-situ measurements and continued monitoring are crucial for accurately assessing and modelling future basal melt rates, as well as understanding the complex dynamics driving ice-shelf stability and sea-level change.
18 Dec 2023Submitted to ESS Open Archive
27 Dec 2023Published in ESS Open Archive