Aero-measurements during the 1983–84 and 1985–86 field seasons showed that the ice in the central part of Filchner-Ronne Ice Shelf is more than 250 m thicker than has been assumed previously. In the margin area a double layering of the ice was found, with disappearing bottom reflections farther inland. High absorption of approximately 0.3 dB/m in the lower layer and a decreasing reflectivity at the ice / sea-water interface, probably caused by bottom freezing, have been estimated. Aero-measurements were used to map the surface elevation of the ice, with an accuracy of approximately 3 m. From the plot of ice thickness against surface elevation it was possible to obtain a calibration curve for isostatic conditions. Large deviations from this plot with an ice thickness which is apparently too small (they seem to be isostatic anomalies) were found in the central part of the ice shelf. The true ice thickness could easily be calculated and mapped from these anomalies and the electromagnetically measured thickness. From the map based on flights made in 1983–84 the site for a bore hole was chosen in the central part of the ice shelf with an estimated ice thickness of about 450 m, instead of the less than 200 m deduced by an electromagnetic reflection (EMR) method. Hot-water drilling by the ground party of our group (H. Engelhardt and J. Determann) revealed an ice thickness of 465 m at this site.

The depth of reflecting layers in Arctic ice sheets has been determined by electromagnetic echo sounding, using a varying distance between transmitter and receiver to determine the radar wave velocity. The depth of the radar reflecting layers is compared with a profile of electrical conductivity measurements (ECMs) from the Greenland Ice Core Project (GRIP) ice core, in order to determine the velocity of the radar waves in the ice cap. By using several reflecting layers, it is possible to isolate the firn correction of the wave velocity and to estimate the accuracy of the calculated electromagnetic wave velocity. The measured firn correction is compared with the correction calculated from the density profile, and a comparison between the depth profiles of ECM and radar based on the corrected electromagnetic wave velocity is presented. This profile shows that acid layers, which originate from major volcanic eruptions, show up as reflecting radar horizons.

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In 1985–86, western Neuschwabenland was surveyed with an electromagnetic reflection system (EMR) over flight tracks totalling 6100 km. The area spans a triangle from Ekström Ice Shelf and Heimefront Range to the Kraul Mountains [Vestfjella] and covers 48 000 km2. Data on surface elevation, ice thickness and bedrock topography are presented in maps. The bedrock-elevation map shows more detail than earlier compilations, with a remarkable graben-like structure north of the Heimefront Range and large areas of bedrock below sea-level. In the same season, tracks totalling 1600 km were flown over Berkner Island. High electromagnetic reflectivity was found over the southern part of Berkner Island, whereas the northern part showed considerably lower reflectivity. We believe that this is due to melting conditions in the southern part and freezing conditions in the northern part.

In [980-81, [983-84 and [985-86 airborne surveys with an electromagnetic reflection (EMR) system were made of Ekstrom Ice Shelf, Antarctica. The EMR data were supplemented by measurements of surface elevation with radar a[timetry during flights at a constant pressure altitude. The accurate measurement of ice thickness in areas with clearly developed bottom reflectors was used to generate a plot of surface elevation against ice thickness. The effect of changing barometric pressure during the flights could be reduced by this means. Elevations were calibrated over the open sea at the beginning and end of each flight.On the basis of these data, the surface elevation, ice thickness and i50static anomalies have been mapped over the ice shelf.