Extraction of Ice Sheet Layers From Two Intersected Radar Echograms Near Neem Ice Core in Greenland

Abstract

ABSTRACT:Accumulation of snow and ice over time result in ice sheet layers. These can be remotely sensed where there is a contrast in electromagnetic properties, which reflect variations of the ice density, acidity and fabric orientation. Internal ice layers are assumed to be isochronous, deep beneath the ice surface, and parallel to the direction of ice flow. The distribution of internal layers is related to ice sheet dynamics, such as the basal melt rate, basal elevation variation and changes in ice flow mode, which are important parameters to model the ice sheet. Radar echo sounder is an effective instrument used to study the sedimentology of the Earth and planets. Ice Penetrating Radar (IPR) is specific kind of radar echo sounder, which extends studies of ice sheets from surface to subsurface to deep internal ice sheets depending on the frequency utilised. In this study, we examine a study site where folded ice occurs in the internal ice sheet south of the North Greenland Eemian ice drilling (NEEM) station, where two intersected radar echograms acquired by the Multi-channel Coherent Radar Depth Sounder (MCoRDS) employed in the NASA's Operation IceBridge (OIB) mission imaged this folded ice. We propose a slice processing flow based on a Radon Transform to trace and extract these two sets of curved ice sheet layers, which can then be viewed in 3-D, demonstrating the 3-D structure of the ice folds.

Review article: Feature tracing in radio-echo sounding products of terrestrial ice sheets and planetary bodies

“…Deeper boundaries are more difficult than shallow ones for SAMPA to trace because of attenuation and low contrast resulting from low variance in trace amplitude. Xiong and Muller (2016) mention the difficulty of tracing internal IRHs are due to presence of noncontiguous IRHs, and relating that to local anomalies such as folds and crevasses caused by ice dynamics. The underlying method here is also the Radon transform similar to Onana et al (2015) to extract IRHs from radargrams of NEEM station.…”

A New Method for Automatically Tracing Englacial Layers from MCoRDS Data in NW Greenland

“…For each seed point, one layer-tracing procedure is accomplished based on three assumptions, which are (1) the englacial layers are quasi-parallel; (2) there are no crossing layers; and (3) within a short distance, the englacial layers can be approximated by a straight line [15,17,18]. Figure 7 illustrates the layer-tracing procedure.…”