Basal melting and oceanic observations beneath Fimbulisen, East Antarctica

• Main Authors: Lindbäck, Katrin, Darelius, Elin, Moholdt, Geir, Vankova, Irena, Hattermann, Tore, Lauber, Julius, Steur, Laura de
• Format: Other/Unknown Material
• Language: unknown
• Published: Authorea, Inc. 2023
• Subjects: Antarctic; Austral; Dronning Maud Land; East Antarctica; Fimbulisen; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: http://dx.doi.org/10.22541/essoar.170365303.33631810/v1

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, marked by substantial sub-weekly variability ranging from 0.3 to 3.8 m yr. 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 vs 0.8 m yr). 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.