Strong spatial variability of snow accumulation observed with helicopter-borne GPR on two adjacent Alpine glaciers

This study compares high-resolution helicopter-borne radar measurements to extensive ground-based profiling of the snow cover on Findel- and Adler Glacier, Switzerland. The results demonstrate that derived accumulation values of either method are well in accordance. The spatial distribution of radar based snow depth allows a clear distinction of three zones of different accumulation characteristics: ( 1) The lower part of Findel Glacier shows a clear altitudinal trend while ( 2) the upper part has no trend in altitude but high spatial fluctuations in snow depth. ( 3) Adler Glacier's accumulation characteristics are similar to zone ( 2). However, despite their close vicinity, accumulation on ( 3) is reduced by 40% compared to ( 2). The observed strong spatial variability emphasises the need for spatially continuous measurements for studies involving accumulation on glaciers. Finally, reasons for observed variations ( e. g., preferential snow deposition and snow redistribution) are discussed.