A comparison of radio-echo sounding data and electrical conductivity of the GRIP ice core

Journal of Glaciology, Vol. 46, No. 154, p. 369-374, 2000

L. Hempel, F. Thyssen
Westfälische Wilhelms-Universität, Institut für Geophysik, Correnstrasse 24, D-48149 Münster, Germany.
N. Gundestrup, H.B. Clausen
Departement of Geophysics, The Niels Bohr Institute of Astronomy, Physics and Geophysics, University of Copenhagen.
H. Miller
Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven, Germany.

The depth of reflecting layers in Arctic ice sheets has been determined by electromagnetic echo sounding, using a avrying distance between transmitter and receiver to determine the radar wave velocity. The depth of the radar reflecting layers is compared with a profile of electrical conductivity measurements (ECMs) from the Greenland Ice Core Project (GRIP) ice core, in order to determine the velocity of the radar waves in the ice cap. By using several reflecting layers, it is possible to isolate the firn correction of the wave velocity and to estimate the accuracy of the calculated electromagnetic wave velocity. The measured firn correction is compared with the correction calculated from the density profile, and a comparison between the depth profiles of ECM and radar based on the corrected electromagnetic wave velocity is presented. This profile shows that acid layers, which originate from major volcanic eruptions, show up as reflecting radar horizons.