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

Siting Xiong,Jan-Peter Muller,Raquel Carretero

doi:10.3390/rs10010043

Siting Xiong, Jan-Peter Muller + Show 1 more

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https://doi.org/10.3390/rs10010043

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Abstract

Englacial layering reflects ice dynamics within the ice bodies, which improves understanding of ice flow variation, past accumulation rates and vertical flows transferring between the surface and the underlying bedrock. The internal layers can be observed by using Radar Echo Sounding (RES), such as the Multi-channel Coherent Radar Depth Sounder (MCoRDS) used in NASA’s Operation IceBridge (OIB) mission. Since the 1960s, the accumulation of the RES data has prompted the development of automated methods to extract the englacial layers. In this study, we propose a new automated method that combines peak detection methods, namely the CWT-based peak detection or the Automatic Phase Picker (APP), with a Hough Transform (HT) to trace boundaries of englacial layers. For CWT-based peak detection, we test it using two different wavelets. The proposed method is tested with twelve MCoRDS radio echograms, which are acquired south of the Northern Greenland Eemian (NEEM) ice drilling site, where the folding of ice layers was observed. The method is evaluated in comparison to the isochrones that were extracted in an independent study. In comparison, the proposed new automated method can restore more than 70% of the englacial layers. This new automated layer-tracing method is publicly available on github.

Highlights

The radio echo sounding (RES) technique has been used in glaciology since the 1960s to map the bed topography and layering of the ice sheets in Greenland and Antarctica [1]
We propose a new method of using the CWT-based peak detection [29], or APPpeak detection [30], and the Hough Transform (HT) [31,32] to trace the englacial layers from the Multi-channel Coherent Radar Depth Sounder (MCoRDS) radio echograms
Tracing englacial layers is important for studying ice sheet dynamics yet difficult to achieve with high efficiency and accuracy at the same time

Summary

Introduction

The radio echo sounding (RES) technique has been used in glaciology since the 1960s to map the bed topography and layering of the ice sheets in Greenland and Antarctica [1]. RES operates at low frequencies that are usually tens of megahertz, to achieve penetration depths down to thousands of meters into the ice bodies. Through this technique, pulsed waves are transmitted into the ice body and reflections from interfaces in the ice body are detected, which mark changes in the dielectric properties between adjacent layers. Analysis of these internal reflections, which are thought to be isochronous except for the deepest layers, has shed lights on many aspects of ice dynamics, such as past accumulation rates [2,3], ice flow changes [4,5], bed variations and its relationship with surface conditions [6,7].

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