| High vertical-resolution 0.5-2 GHz frequency-modulated continuous-wave radar data collected near Summit on the Greenland Ice Sheet reveal continuous horizons connecting the GRIP and GISP2 deep ice cores. Traced radar horizons to 150 meters depth are compared to physical properties, age-depth relationships, and accumulation rates from ice cores near Summit. Having established the radar horizons as annual accumulation markers, a 350-year record of accumulation rate is derived and analyzed spatially and temporally. Accumulation characteristics such as spatial noise, long-term accumulation rate, and climate fluctuations are determined. Averaging accumulation across 1000-2000 m eliminates most spatial noise associated with small-scale surface perturbations, providing a good approximation of the local accumulation rate. Overall, a detailed record of accumulation is gained, indicating that near-surface radar surveys can take the place of shallow ice cores for examining accumulation history, improving knowledge of spatial and temporal variability, spatial and temporal noise, and other accumulation characteristics. |
