Repeat airborne or satellite measurements of surface elevation over ice caps are often used to calculate glacier‐wide surface mass changes over time. However, these measurements typically do not account for vertical ice motion caused by firn densification and/or ice flow, so the effect of these factors for mass change measurements over an entire ice cap are currently poorly constrained. In this study, we update NASA Airborne Topographic Mapper (ATM) altimetry elevation changes across Penny Ice Cap (Baffin Island, Canada) to assess total changes in ice mass from 2005–2014, relative to 1995–2000. Dual‐frequency GPS measurements and temporal changes in ice core density profiles are used to calculate firn densification and ice flow to isolate the component of elevation change due to surface mass change. Envisat satellite imagery is used to delineate the areas impacted by firn densification. These calculations, the first for a Canadian Arctic ice cap, indicate that accounting for firn densification may reduce the inferred surface mass loss by ~13–15%. Overall, there has been a fourfold increase in mass loss from Penny Ice Cap between 1995–2000 (−1.3 ± 0.7 Gt a⁻¹) and 2005–2013 (−5.4 ± 1.9 Gt a⁻¹). The rapid upglacier migration of the equilibrium line has left large areas of subsurface firn in the current ablation area and has far outpaced the ice flow response, illustrating that the ice cap is not in equilibrium and out of balance with the current climate.

中文翻译：

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基于2005-2014年为密度致密化修改的高程变化，对巴芬岛潘妮冰帽的近期质量损失率的修订估算

通常使用反复的机载或人造卫星测量冰盖表面高度来计算冰川随时间变化的表面质量变化。然而，这些测量通常不能解决由烧结致密化和/或冰流引起的垂直冰运动，因此，目前这些因素在整个冰盖上进行质量变化测量的影响受到了很大的限制。在这项研究中，我们更新了Penny Ice Cap（加拿大巴芬岛）上的NASA空中地形测绘仪（ATM）测高仪高度变化，以评估2005-2014年相对于1995-2000年的总冰量变化。GPS的双频测量和冰芯密度剖面的时间变化用于计算火成岩密度和冰流，以隔离由于表面质量变化而引起的海拔变化分量。Envisat卫星图像用于描绘受烙印致密化影响的区域。这些计算是加拿大北极冰盖的首次计算，表明考虑到烧成致密化可以将推断的表面质量损失降低约13-15％。总体而言，1995-2000年间，竹P冰帽的质量损失增加了四倍（-1.3±0.7 Gt a^-1）和2005-2013（-5.4±1.9 Gt a ^-1）。平衡线的快速冰川迁移在当前的消融区域中留下了大面积的地下熔岩，并且远远超过了冰流响应，这说明冰盖没有达到平衡并且与当前气候失衡。