Repeatability of Polar Accumulation Time Series From Interannual Repeat Radar Echograms

Ice-penetrating radar is increasingly used to reconstruct surface mass balance (SMB) time series, but questions remain regarding the multi-year consistency of such measurements. We compare annually resolved SMB time series reconstructed from airborne radar collected in 2011 and 2016 to assess the repeatability of radar-based estimates. We further compare the results between the flights using a traditional manual method to determine annual layers and an automated probabilistic method. The results indicate low biases (2.98%–6.54%) between different collection times and methods with root-mean-square errors of 27.1%–36.5%. Overall bias distributions minimally differ based on the collection time and reconstruction method, although specific sites can deviate more substantially. These results suggest that ice-penetrating radar can be used to reconstruct temporally stable annually resolved SMB time series even when data collection is separated by several years. This outcome permits large syntheses of radar-derived SMB time series with less regard to homogeneous collection times.