none 10.1190/geo2011-0375.1 Society of Exploration Geophysicists Society of Exploration Geophysicists 186 56409680 5981 2025121111494053100 10.1190 2025-12-11T16:49:48Z 2012-07-09T18:37:42Z 13 Geophysics 1942-2156 0016-8033 07 1 2012 07 01 2012 77 4 Andreas A. Pfaffhuber Norwegian Geotechnical Institute 1 , Oslo, . E-mail: aap@ngi.no ; yk@ngi.no . Norway Stefan Hendricks Alfred Wegener Institute for Polar and Marine Research 2 , Bremerhaven, . E-mail: stefan.hendricks@awi.de . Germany Yme A. Kvistedal Norwegian Geotechnical Institute 1 , Oslo, . E-mail: aap@ngi.no ; yk@ngi.no . Norway ABSTRACT The polar ocean’s sea ice cover is an unconventional and challenging geophysical target. Helicopter electromagnetic (HEM) sea-ice thickness mapping is currently limited to 1D interpretation due to traditional procedures and systems. These systems are mainly sensitive to layered structures, ideally set for the widespread flat (level) ice type. Because deformed sea ice (e.g., pressure ridges) is 3D and usually also heterogeneous, ice thickness errors up to 50% can be observed for pressure ridges using 1D approximations for the interpretation of HEM data. We researched a new generation multisensor, airborne sea ice explorer (MAiSIE) to overcome these limitations. Three-dimensional finite-element modeling enabled us to determine that more than one frequency is needed, ideally in the range 1–8 kHz, to improve thickness estimates of grounded sea-ice pressure ridges that are typical of 3D sea ice structures. With the MAiSIE system, we found a new electromagnetic concept based on one multifrequency transmitter loop and a 3C receiver coil triplet with active digital bucking. The relatively small weight of the EM components freed enough payload to include additional scientific sensors, including a cross-track lidar scanner and high-accuracy inertial-navigation system combined with dual-antenna differential GPS. Integrating the 3D ice-surface topography obtained from the lidar with the EM data at frequencies from 500 Hz to 8 kHz in x-, y-, and z-directions, significantly increased the accuracy of sea-ice pressure-ridge geometry derived from HEM data. Initial test flight results over open water showed the proof-of-concept with acceptable sensor drift and receiver sensitivity. Noise levels were relatively high (20–250 parts-per-million) due to unwanted interference, leaving room for optimization. The 20 ppm noise level at 4.1 kHz is sufficient to map level ice thickness with 10 cm precision for sensor altitudes below 13 m. 07 1 2012 07 01 2012 07 09 2012 WB109 WB117 10.1190/geo2011-0375.1 https://pubs.geoscienceworld.org/geophysics/article/77/4/WB109/73918/Progressing-from-1D-to-2D-and-3D-near-surface https://pubs.geoscienceworld.org/seg/geophysics/article-pdf/77/4/WB109/3231594/geo2011-0375.pdf https://pubs.geoscienceworld.org/seg/geophysics/article-pdf/77/4/WB109/3231594/geo2011-0375.pdf http://geophysics.geoscienceworld.org/cgi/doi/10.1190/geo2011-0375.1 Impacts of a warming arctic: Arctic climate impact assessment 2004 0016-8033 Geophysics Anderson 44 1979 10.1190/1.1441007 Numerical integration of related Hankel transforms of order 0 and 1 by adaptive digital filtering 0016-8025 Geophysical Prospecting Beamish 51 2003 10.1046/j.1365-2478.2003.00353.x Airborne EM footprints 1530-437X IEEE Sensors Journal Coillot 10 2010 10.1109/JSEN.2009.2030977 Principle and performance of a dual-band search coil magnetometer: A new instrument to investigate fluctuating magnetic fields in space 0812-3985 Exploration Geophysics Davis 37 2006 10.1071/EG06355 Pendulum motion in airborne HEM systems 0016-8033 Geophysics Fitterman 69 2004 10.1190/1.1801937 Effect of bird maneuver on frequency-domain helicopter EM response European commission, Arctic sea-ice thickness: Past, present & future Haas 2006 Airborne electromagnetic measurements of sea-ice thickness: Methods and applications Hendricks S. , 2009, Validation of altimetric sea-ice thickness measurements with a helicopter based electromagnetic induction method: Ph.D. thesis, (in German), University of Bremen. 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