Recent elevation changes of Penny Ice Cap, Baffin Island, corrected for ice dynamics and firn densification
2016 (English)In: Journal of Geophysical Research - Earth Surface, ISSN 2169-9003, E-ISSN 2169-9011Article in journal (Refereed) Submitted
Measurements of ice cap changes are often based on geodetic methods, which calculate glacier-wide mass loss from elevation change over time. However, these measurements typically don’t account for vertical ice motion caused by firn compaction and/or ice dynamics, so the significance 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. Differential GPS measurements and temporal changes in ice core density profiles are used to calculate vertical motion and isolate the ATM altimetry elevation change due to mass loss. 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 failure to properly account for vertical ice motion results in a 19% overestimation of mass loss. The results, when corrected for vertical motion, are largely insensitive to the assumed density in the firn zone (900 or 800 kg m‑3). Overall, there has been a four-fold increase in mass loss from Penny Ice Cap between 2005-2013 (-5.4 ± 1.9 Gt a-1) compared to the mid-1990s (-1.3 ± 0.7 Gt a-1). The relatively rapid upglacier migration of the equilibrium line altitude (ELA) has left large areas of sub-surface firn in the current ablation area, and has far outpaced the dynamic response of the ice cap to the observed mass loss.
Place, publisher, year, edition, pages
American Geophysical Union (AGU), 2016.
Arctic, glaciers, Canada, climate change, glaciology, remote sensing
Earth and Related Environmental Sciences
IdentifiersURN: urn:nbn:se:uu:diva-303692OAI: oai:DiVA.org:uu-303692DiVA: diva2:972771
Manuscript # 2016JF0040592016-09-222016-09-222016-09-27