Revised Estimates of Recent Mass Loss Rates for Penny Ice Cap, Baffin Island, Based on Elevation Changes Modified for Firn Densification

Repeat airborne or satellite measurements of surface elevation over ice caps are often used to calculate glacier-wide changes in surface mass balance (ice loss or gain) over time. However, these mass balance approximations typically do not account for the change in elevation due to the compaction of firn (snow that has survived at least one year), so the effect of densification on mass change estimates over an entire ice cap are currently poorly constrained. In this study, we update elevation changes over Penny Ice Cap (Baffin Island, Canada) for 2005-2013 and 2013-2014 using repeat measurements of surface elevation. We modify these data to remove the elevation change due to the compaction of firn to improve the approximation of ice loss. The firn compaction is calculated using precise GPS measurements and ice cores collected near the summit of the ice cap.The majority of these data were collected between 2006-2014. These data were collected within a general monitoring program for Penny Ice Cap to obtain information on the mass balance, changes in the densification rate, and motion of Penny Ice Cap.