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Norwegian-American Scientific Traverse of East Antarctica

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DEP - dielectric profiling along ice cores for determination of electrical properties, by the Norwegian Polar Institute

Measuring DEP in the labDEP is a non-destructive technique for measuring electrical conductivity and dielectric permitivity of ice cores. The DEP device is applied by moving two curved electrodes along the ice core (Wilhelms et al., 1998). Values are measured at intervals of 5 mm, thus enabling a high-resolution determination of electrical properties. Electrical properties are largely influenced by the total salt content as well as the acidity of the ice. Thus, DEP-data are useful for detection of volcanic layers in the ice.

Image: Photo by G. Rotschky.

In high accumulation areas annual-layer counting is possible, but in low accumulation areas a chronology based on comparison of DEP records with each other is required. Volcanic layers in Antarctica are well documented and have been used to date ice cores (Hofstede et al., 2004).

DEP measuring benchIn addition, DEP data are necessary for the calibration of shallow radar data and the conversion of two-way travel time to depth. Thus, our DEP measurements will aid in the interpretation of GPR data as well as in dating the ice cores. Sufficiently dated ice cores and radar layers are crucial for the determination of accumulation rates.

Image: Dielectric profiling in the field. Source: AWI Bremerhaven.

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