Comparison of snow accumulation events on two High-Arctic glaciers to model-derived and observed precipitation

We evaluate how precipitation forcing data used in glacier mass balancemodels characterize snow accumulation events on synoptic timescales for two glaciersin north-western Svalbard (Kongsvegen and Holtedahlfonna). Using sonic ranger (snow depth) and wind speed data from automatic weather stationslocated on the glaciers, we distinguish accumulation events occurring under either calm or windy conditions. We show clear differences in the timing and magnitude of snow accumulation events between the two neighbouring glaciers, illustrating the spatial heterogeneityof snow accumulation in this region. The accumulation measurements show that at equivalent elevations, Kongsvegen receives more snowfall than neighbouring Holtedahlfonna, and that Kongsvegen is more affected by wind-driven snow redistribution than Holtedahlfonna. This is consistent with the synoptically-driven precipitation patterns in the region. Accumulation events are then compared to precipitation data from the nearest meteorological station in Ny-Alesund (ca. 30 km distant) and to a downscaledsnowfall data product based on the ERA- Interimreanalysis (nearest gridpoint ca. 300 m distant). Evaluation of the synchrony of observed events at the glaciersites and the precipitation products shows that the ERA- Interimprecipitation data reproduce more snowfall events than the Ny-Alesund station data, suggesting that the precipitation fields from distributed reanalysis data provide a more reasonable representation of accumulation on the study glaciers, even over short timescales.