Day 4

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Paper title Seasonal land ice-flow variability across the Antarctic Peninsula
Authors
  1. Karla Boxall Scott Polar Research Institute, University of Cambridge Speaker
  2. Frazer Christie Scott Polar Research Institute, University of Cambridge
  3. Ian Willis UNIVERSITY OF CAMBRIDGE
  4. Jan Wuite ENVEO IT GmbH
  5. Thomas Nagler ENVEO IT GmbH
Form of presentation Poster
Topics
  • A9. Polar Science and Cryosphere
    • A9.04 Mass Balance of the Cryosphere
Abstract text Three decades of routine Earth Observation have revealed the progressive demise of the Antarctic Ice Sheet, evinced by accelerated rates of ice thinning, retreat and flow. These phenomena, and those pertaining to ice-flow acceleration, especially, are predominantly constrained from temporally limited observations acquired over inter-annual timescales or longer. Whereas ice-flow variability over intra-annual timescales is now well documented across, for example, the Greenland Ice Sheet, little-to-no information exists surrounding seasonal ice-flow variability in Antarctica. Such information is critical towards understanding short-term glacier dynamics and, ultimately, the ongoing and future imbalance of the Antarctic Ice Sheet in a changing climate.

Here, we use high spatial- and temporal- (6/12-daily) resolution Copernicus Sentinel-1a/b synthetic aperture radar (SAR) observations spanning 2014 to 2020 to provide evidence for seasonal flow variability of land ice feeding the climatically vulnerable George VI Ice Shelf (GVIIS), Antarctic Peninsula. Between 2014 and 2020, the flow of glaciers draining to GVIIS from Palmer Land and Alexander Island increased during the austral summer (December – February) by ~0.06 m d⁻¹ (22 m yr⁻¹). These observations exceed prescribed (root median square) error limits totalling ~0.02 m d⁻¹ (7.5 m yr⁻¹). This variability is corroborated by independent observations of ice flow as imaged by the Landsat 8 Operational Land Imager that are not impacted by firn penetration and other effects known to potentially bias SAR-derived velocity retrievals over monthly timescales or shorter. Alongside an anomalous reduction in summertime surface temperatures across the Antarctic Peninsula since c.2000, differences in the timing of ice-flow speedup we observe between the Palmer Land and Alexander Island glaciers implicate oceanic forcing as the primary control on this seasonal signal.