Evaluation of a Portable Electromagnetic Induction Instrument for Measuring Sea Ice Thickness

• Main Authors: Kovacs, Austin, Morey, Rexford M.
• Other Authors: COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
• Format: Text
• Language: English
• Published: 1991
• Subjects: Snow; Ice and Permafrost; Test Facilities; Equipment and Methods; Electricity and Magnetism; *THICKNESS; *MEASUREMENT; *SEA ICE; FIELD TESTS; NUMERICAL ANALYSIS; PROCESSING EQUIPMENT; DISPLAY SYSTEMS; ELECTROMAGNETIC INDUCTION; ICE; MODULES(ELECTRONICS); INSTRUMENTATION; SEA WATER; SIMPLIFICATION; REMOTE SYSTEMS; ARCTIC REGIONS; PACK ICE; CONDUCTIVITY; PLUG IN UNITS; DATA PROCESSING; PORTABLE EQUIPMENT; *MEASURING INSTRUMENTS; *ELECTROMAGNETIC INDUCTION; PARK ICE; ELECTROMAGNETIC FIELDS; SOUNDING; MAGNETIC FIELDS; Arctic; Ice; permafrost; Sea ice
• Online Access: http://www.dtic.mil/docs/citations/ADA240974; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA240974

Field trials using a man-portable Geonics, Ltd., EM31 electromagnetic induction sounding instrument, with a plug-in data processing module, for the remote measurement of sea ice thickness, are discussed. The processing module was made by Flow Research Inc., to directly measure sea ice thickness and show the result in a numerical display. The EM31-processing module system was capable of estimating ice thickness within 10% of the true value for ice from about 0.7 to 3.5 m thick, the oldest undeformed ice in the study area. However, since seawater under the Arctic pack ice has a relatively uniform conductivity (2.5 + or - 0.05 S/m), a simplified method, which can be used for estimating sea ice thickness using jet an EM31 instrument, is discussed. It uses only the EM31's conductivity measurement, is easy to put into use and does not rely on theoretically derived look-up tables or phasor diagrams, which may not be accurate for the conditions of the area.