HIGH-RESOLUTION DIELECTRIC PROFILING OF ICE CORES

A new method for high-resolution (3 mm) dielectric profiling of ice cores is described. The method measures the capacitance and conductance of the ice at a single frequency (chosen to be 50 kHz in this case). The technique requires only a few minutes per metre of core, and no sophisticated data analysis. The system is designed to operate on ice cores that have been cut longitudinally, providing one flat and one curved surface. The 50 kHz conductance is dependent on the acid and neutral-salt concentrations in the ice. The new method was tested successfully on the GRIP core from Summit, Greenland, in 1991. It is useful for detecting seasonal variations in impurities in both acidic Holocene ice and in normally alkaline Wisconsin ice.