
%0 Journal Article
%A Reid, J.E. 
%A Vrbancich, J. 
%A Worby, A.P. 
%T A comparison of shipborne and airborne electromagnetic methods for Antarctic sea ice thickness measurements
%J Exploration Geophysics
%D 2003/06/01
%V 34
%N 2
%P 46-50
%K 
%R https://doi.org/10.1071/EG03046
%U https://www.publish.csiro.au/paper/EG03046 
%X The three-dimensional modelling program MARCO_AIR has been used to calculate the response of idealized sea-ice pressure ridge models to practical airborne and shipborne electromagnetic systems. The model results clearly show the superior lateral resolution of the horizontal coplanar shipborne system compared to higher-altitude airborne measurements. However, sea-ice keel thicknesses estimated via one-dimensional inversion of shipborne single-frequency electromagnetic data are strongly dependent on relatively small variations in survey altitude. One-dimensional inversion of synthetic helicopter electromagnetic data over three-dimensional pressure ridge models shows that the maximum ice keel thickness is consistently underestimated, although airborne EM methods yield reliable thickness estimates over level ice. The vertical-coaxial coil survey geometry offers excellent lateral resolution of multiple targets, but the anomalies of typical Antarctic sea-ice pressure ridges would be too small to be reliably detected in practical surveys using an HEM system with a transmitter-receiver separation of 2?3 m. For an HEM system with a coil separation of 8 m, the vertical coaxial responses are larger, and lateral resolution of the vertical coaxial measurements at a flight height of 20 m is superior to a close-coupled horizontal coplanar system flown at an altitude of 10 m. 
