Airborne Electromagnetic Sensing of Sea Ice Thickness

A conventional frequency domain helicopter-borne electromagnetic (HEM) system can be used to map sea ice keels with a reasonable degree of accuracy. A preliminary interpretation of the acquired data can be made manually with the help of a nomogram or automated with the use of a table look-up routine...

Full description

Bibliographic Details
Main Authors: Becker, Alex, Liu, Guimin
Other Authors: CALIFORNIA UNIV BERKELEY DEPT OF MATERIALS SCIENCE AND MINERAL ENGINEERING
Format: Text
Language:English
Published: 1988
Subjects:
Snow
Ice and Permafrost
Computer Programming and Software
Electricity and Magnetism
*DEPTH FINDING
*SEA ICE
THICKNESS
FORWARD AREAS
COMPUTATIONS
DETECTION
COMPUTERS
AIRBORNE
SOLUTIONS(GENERAL)
HELICOPTERS
FLIGHT
TABLES(DATA)
INVERSION
ELECTROMAGNETISM
HEIGHT
NOMOGRAPHS
FREQUENCY
DATA PROCESSING
SEA ICE KEELS
ELECTROMAGNETIC DETECTION
Ice
permafrost
Sea ice
Online Access:http://www.dtic.mil/docs/citations/ADA214460
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA214460
Description
Summary:A conventional frequency domain helicopter-borne electromagnetic (HEM) system can be used to map sea ice keels with a reasonable degree of accuracy. A preliminary interpretation of the acquired data can be made manually with the help of a nomogram or automated with the use of a table look-up routine on a small computer. Such data may also be more accurately interpreted with the use of an adaptation of Occam's inversion. This scheme allows for the practical non-uniqueness of the inverse solution but selects the smoothest keel shape that is consistent with the field data. The inversion method is much more computationally intensive than the table look-up technique. While the latter can be implemented on a small computer to form an interactive in-flight interpretation system, the inversion technique involves many forward computations and , for the present, is best reserved for past flight data analysis. It is possible that this difficulty can be resolved with the use of specialized computing equipment. In the strict sense both proposed interpretation techniques are only suitable for use on data acquired over two dimensional features whose strike length (measured in a direction perpendicular to the flight line) is much greater than the flight height. Examination of the anomalies for three-dimensional keels however, reveals that good data interpretation is possible whenever the keel strike length exceeds the system height by a factor of three.

Similar Items