IAN HOWAT

A three-year record of weekly snow water equivalent (SWE) accumulation at Summit Camp, central Greenland Ice Sheet, obtained by direct sampling, is presented. While the overall SWE accumulation of 24.2 cm w.e. per year matches long-term ice core estimates, variability increases at shorter time scales. Half of the annual SWE accumulation occurs during a few large events, with the average accumulation rate decreasing 35% between the first and second halves of the record coinciding with exceptional anticyclonic conditions in the spring and summer of 2019. No seasonality in accumulation is detected. Rather, local accumulation rates appear to be significantly impacted by wind redistribution that obscures temporal patterns in snowfall. Surface snow density is consistent, on average, with previously measured values but does not correlate with near surface temperature or wind speed. Two surface mass balance reanalysis models significantly underestimate accumulation rates at Summit Camp. This is concerning because such models are often used to estimate ice sheet mass loss.