Abstract:

The Bach Ice Shelf in the Antarctic Peninsula is one of the most rapidly melting area of the Antarctic ice sheet. Each summer, large volumes of meltwater are stored and routed on the ice surface and significantly impact the stability of the ice shelf. However, our knowledge of long-term dynamic variation of the surface meltwater of the Bach Ice Shelf remains limited. We extracted surface meltwater on the Bach Ice Shelf using 21 scenes of Landsat-8 Operational Land Imager (OLI) images, and we compared the remotely sensed volume of meltwater and the surface runoff simulated by the MERRA-2 model. Results show that: (1) 91.7% of surface meltwater ponds on the ice shelf are outside the grounding line, and >90% of meltwater on the ice shelf is close to the grounding line (< 7 km); (2) surface meltwater is routed among different supraglacial lakes through supraglacial river networks, and does not reach the front edge of the ice shelf or enter the ocean; (3) in general, the area and volume of remotely sensed surface meltwater increased from 2013 to 2020. Surface meltwater commonly appears in the middle of December around the grounding line, expands until mid-January, and then starts to shrink around late January as the surface runoff declines; (4) the volume of surface meltwater is significantly smaller than the cumulative surface runoff simulated by the MERRA-2, implying that the MERRA-2 model may overestimate surface meltwater runoff.

Key words: surface meltwater, supraglacial lake, supraglacial river network, surface mass balance model, Antarctic Peninsula