C050-08
Record surface meltwater ponding on the Northern George VI Ice Shelf, Antarctic Peninsula, during the 2019/2020 melt season

Monday, 14 December 2020: 11:58
Virtual
Alison F Banwell, University of Colorado Boulder, Cooperative Institute for Research in Environmental Sciences, Boulder, United States, Rajashree Datta, University of Maryland, Earth System Science Interdisciplinary Center, Greenbelt, MD, United States; NASA Goddard Space Flight Center, Cryospheric Sciences Laboratory, Code 615, Greenbelt, NY, United States, Rebecca L Dell, University of Cambridge, Scott Polar Research Institute, Cambridge, United Kingdom, Mahsa S Moussavi, University of Colorado at Boulder, Boulder, CO, United States; National Snow and Ice Data Center, Boulder, CO, United States and Christopher A. Shuman, University of Maryland, Baltimore County, Joint Center for Earth Systems Technology, Greenbelt, MD, United States; NASA Goddard Space Flight Center, Cryospheric Sciences Laboratory, Code 615, Greenbelt, MD, United States
Recorded Presentation
Abstract:
The evolution of surface and shallow subsurface meltwater ponding across Antarctic ice shelves has important implications for their (in)stability, as demonstrated by the 2002 rapid collapse of the Larsen B Ice Shelf. Ice-shelf break-up may be triggered by stress variations associated with meltwater movement, ponding and drainage. In the austral summer of 2019/2020, we observed record surface meltwater ponding on the northern part of the George VI Ice Shelf (GVIIS), Antarctic Peninsula; an event which coincided with record-setting surface air temperatures.

For the austral summers between 2013 and 2020, we calculate areal extents and volumes of surface meltwater ponding on the GVIIS by applying an existing threshold-based algorithm to all available cloud-free optical images from the Landsat 8 and Sentinel-2 satellites. Both the maximum total area (1800 km2) and the total volume (0.62 km3) of meltwater observed on a single day (19 January, 2020) across the ice shelf in the 2019/2020 melt season were approximately twice as large as on any day in the previous record known melt season (2017/2018). For the austral summers between 2007 and 2020, we also calculate the meltwater duration (days) using a new retrieval algorithm applied to enhanced resolution C-band radar backscatter image time series collected by EUMETSAT’s Advanced SCATterometer (ASCAT), aboard the tandem polar-orbiting satellites MetOp-A and MetOp–B. The meltwater duration observed in the 2019/2020 austral summer over the northern GVIIS was exceptional compared to the 12 previous melt seasons. Both our Landsat 8/Sentinel-2- and ASCAT- derived results are correlated with surface air temperature and wind velocity data from the British Antarctic Survey’s Fossil Bluff automatic weather station on the western margin of the GVIIS.

Although the northern GVIIS has the most extensive and the longest history of surface ponding of any remaining Antarctic Peninsula ice shelf, its retreat rates have thus far been relatively gradual; likely due to its dominantly compressive flow regime.

<< Previous Abstract | Next Abstract