Origin of englacial stratigraphy at three deep ice core sites of the Greenland Ice Sheet by synthetic radar modelling

• Published in: Journal of Glaciology
• Main Authors: Seyedhamidreza Mojtabavi, Olaf Eisen, Steven Franke, Daniela Jansen, Daniel Steinhage, John Paden, Dorthe Dahl-Jensen, Ilka Weikusat, Jan Eichler, Frank Wilhelms
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2022
• Subjects: Anisotropic ice; ice core; radio-echo sounding; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Greenland; Ice Sheet; Journal of Glaciology; NGRIP
• Online Access: https://doi.org/10.1017/jog.2021.137; https://doaj.org/article/3c7f436ec5da43ccb41fea72d2e50157

During the past 20 years, multi-channel radar emerged as a key tool for deciphering an ice sheet's internal architecture. To assign ages to radar reflections and connect them over large areas in the ice sheet, the layer genesis has to be understood on a microphysical scale. Synthetic radar trace modelling based on the dielectric profile of ice cores allows for the assignation of observed physical properties’ variations on the decimetre scale to radar reflectors extending from the coring site to a regional or even whole-ice-sheet scale. In this paper we rely on the available dielectric profiling data of the northern Greenland deep ice cores: NGRIP, NEEM and EGRIP. The three records are well suited for assigning an age model to the stratigraphic radar-mapped layers, and linking up the reflector properties to observations in the cores. Our modelling results show that the internal reflections are mainly due to conductivity changes. Furthermore, we deduce fabric characteristics at the EGRIP drill site from two-way-travel-time differences of along and across-flow polarized radarwave reflections of selected horizons (below 980 m). These indicate in deeper parts of the ice column an across-flow concentrated c-axis fabric.