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The footprint/altitude ratio for helicopter electromagnetic sounding of sea-ice thickness; comparison of theoretical and field estimates

Austin Kovacs, J. Scott Holladay and Clyde J. Bergeron
The footprint/altitude ratio for helicopter electromagnetic sounding of sea-ice thickness; comparison of theoretical and field estimates
Geophysics (April 1995) 60 (2): 374-380

Abstract

Helicopter-towed electromagnetic (HEM) induction sounding systems are typically used for geologic surveys. More recently, HEM systems have been used for the remote measurement of sea-ice thickness and shallow sea bathymetry. An important aspect of this remote sensing technology is the area, or footprint, in which the secondary field is predominantly generated by induced currents. A knowledge of the size of the footprint is important to understanding the accuracy of HEM sounding results over lateral variations in relief or conductivity. Conventional wisdom among workers in the field held that the footprint diameter is a few times the HEM antenna altitude. We confirm this view using airborne measurements over sea ice to calculate the footprint size/antenna altitude ratio. These findings are compared to various theoretical estimates and are found to be in reasonable agreement. For a vertical coaxial coil antenna arrangement, the apparent footprint diameter was found to be about 1.3 times the antenna height above the sea-ice/water interface, and for a horizontal coplanar coil figuration the ratio is about 3.8 times the antenna height.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 60
Serial Issue: 2
Title: The footprint/altitude ratio for helicopter electromagnetic sounding of sea-ice thickness; comparison of theoretical and field estimates
Affiliation: U. S. Army Cold Regions Research and Engineering Lab., Hanover, NH, United States
Pages: 374-380
Published: 199504
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 10
Accession Number: 1995-032928
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: Geonex Aerodat, CAN, CanadaUniversity of New Orleans, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 199512
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