Radio-echo soundings on Icelandic temperate glaciers: history of techniques and findings

Helgi Björnsson,Finnur Pálsson

doi:10.1017/aog.2020.10

Abstract

AbstractSince the mid-1970s radio-echo soundings have been conducted on Iceland's temperate glaciers. Since then, low-frequency radar technology has furthered the study of most of the island's ice caps. Their masses and volumes have been quantified and detailed subglacial topographic maps produced which demarcate glacial drainage basins and identify subglacial lakes and volcanoes. Even internal tephra layers have been charted. The resulting data have been used to force and validate models of past and future glacier evolution. Many practical applications in glacier hydrology have come into being, including hydropower management, road and bridge planning and the prediction of catastrophic flood paths from subglacial eruption sites. Finally, emerging landscapes can now be foreseen in places where glaciers may soon disappear. These achievements would not have been possible without the advances in RES technology.

Highlights

Up to the mid-1970s, the topography of Icelandic glaciers was scarcely known
Defined areas have been surveyed with such short distances between sounding lines (∼20 m) as to allow for 3D migration (Magnússon, personal communication). This campaign is resulting in high-resolution (∼0.5 to 10 m) glacier surface digital elevation model (DEM) based on several remote sensing methods, with GPS surface profiles aiding local corrections and adjustments to radio-echo sounding (RES) survey data
The development of RES in the mid-1970s resulted in the construction of a low frequency analogue echo system which has been used to explore all the main temperate ice caps in Iceland

Summary

Introduction

Up to the mid-1970s, the topography of Icelandic glaciers was scarcely known. While their extent had been identified (11 000 km2 e.g. Björnsson, 1979) surface maps were inaccurate by as much as ∼100 m of elevation, and the bed topography had only been surveyed at a few dozen places by means of seismic sounding in the 1950s (Eyþórsson, 1952; Holtzscherer, 1954; Rist, 1967). The topography of the island’s major ice caps (Fig. 1) is well known, thanks to depth surveys by radio-echo sounding (RES) and a combination of accurate surface-mapping methods.

Results

Conclusion