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: Mojtabavi, Seyedhamidreza, Eisen, Olaf, Franke, Steven, Jansen, Daniela, Steinhage, Daniel, Paden, John, Dahl-Jensen, Dorthe, Weikusat, Ilka, Eichler, Jan, Wilhelms, Frank
• Other Authors: Villum Investigator IceFlow, University of Bergen and Bergen Research Foundation, Chinese Academy of Sciences and Beijing Normal University, National Institute of Polar Research and Arctic Challenge for Sustainability, Japan, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, A. P. Møller Foundation, University of Copenhagen, Swiss National Science Foundation, US National Science Foundation, Office of Polar Programs, data from CReSIS generated with support from the University of Kansas, NASA Operation IceBridge, French Polar Institute Paul-Emile Victor, Institute for Geosciences and Environmental research
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2022
• Subjects: Earth-Surface Processes; Greenland; ice core; Ice Sheet; Journal of Glaciology; NGRIP
• Online Access: http://dx.doi.org/10.1017/jog.2021.137; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143021001374

Abstract 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.