Abstract

We present a high-resolution airborne radar data set (EGRIP-NOR-2018) for the onset region of the Northeast Greenland Ice Stream (NEGIS). The radar data were acquired in May 2018 with Alfred Wegener Institute’s multichannel ultra-wideband (UWB) radar mounted on the Polar6 aircraft. Radar profiles cover an area of ~24000 km2 and extend over the well-defined shear margins of the NEGIS. The survey area is centred at the location of the drill site of the East Greenland Ice-Core Project (EastGRIP) and several radar lines intersect at this location. The survey layout was designed to: (i) map the stratigraphic signature of the shear margins with radar profiles aligned perpendicular to ice flow, (ii) trace the radar stratigraphy along several flow lines and (iii) provide spatial coverage of ice thickness and basal properties. While we are able to resolve radar reflections in the deep stratigraphy, we can not fully resolve the steeply inclined reflections at the tightly folded shear margins in the lower part of the ice column. The NEGIS is causing the most significant discrepancies between numerically modelled and observed ice surface velocities. Given the high likelihood of future climate and ocean warming, this extensive data set of new high-resolution radar data in combination with the EastGRIP ice core will be a key contribution to understand the past and future dynamics of the NEGIS. The EGRIP-NOR-2018 radar data products can be obtained at the PANGAEA Data Publisher (https://doi.pangaea.de/10.1594/PANGAEA.928569; Franke et al. 2021a).

Highlights

  • The Northeast Greenland Ice Stream (NEGIS) efficiently drains a large area of the Greenland Ice Sheet and is a crucial component of the ice sheet mass balance (Fahnestock et al, 1993; Rignot and Mouginot, 2012)

  • The design of the EGRIP-NOR-2018 radar survey enables a detailed analysis of the bed and englacial stratigraphy: (i) along radar profiles which are parallel to the ice flow (Figure 1c) and (ii) along radar profiles perpendicular to the ice flow, crossing the shear margins (Figure 1b)

  • Folds are tightest in profiles oriented ~90° to the shear margin fold axis

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Summary

Introduction

The Northeast Greenland Ice Stream (NEGIS) efficiently drains a large area of the Greenland Ice Sheet and is a crucial component of the ice sheet mass balance (Fahnestock et al, 1993; Rignot and Mouginot, 2012). It extends from the central ice divide over more than 600 km towards the northeastern coast, where it discharges ice through the three marine-terminating glaciers (79 N Glacier, Zachariae Isbræ and Storstrømmen Glacier). Bons et al (2020) raise the question of how fast flow at the NEGIS onset is possible without an extraordinary high basal heat flux and meltrates

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