Buoyancy‐Driven Flexure at the Front of Ross Ice Shelf, Antarctica, Observed With ICESat‐2 Laser Altimetry. Issue 12 (14th June 2021)

• Record Type: Journal Article
• Authors: Becker, Maya K.; Howard, Susan L.; Fricker, Helen A.; Padman, Laurie; Mosbeux, Cyrille; Siegfried, Matthew R.
• Is Part Of: Geophysical research letters. Volume 48:Issue 12(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-14
• Subjects: iceberg calving -- ice‐ocean interactions -- ICESat‐2 -- ice shelves -- remote sensing; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL091207
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Mass loss from Antarctica's three largest ice shelves is dominated by calving, primarily of large tabular icebergs every few decades. Smaller, more frequent calving events also occur, but it is more difficult to detect them and quantify their contribution to total ice‐shelf mass loss. We used surface elevation data from NASA's ICESat‐2 laser altimeter to examine the structure of the Ross Ice Shelf front between October 2018 and July 2020. Profiles frequently show a depression a few meters deep about 200–800 m upstream of the front, with higher values on the eastern portion of the ice shelf. This structure results from bending due to buoyancy of a submerged ice bench generated by ice‐front melting near the waterline when warm water is present in summer. These bending stresses may cause small‐scale calving events whose frequency would change as summer sea ice and atmosphere–ocean heat exchanges vary over time. Plain Language Summary: Mass loss from Antarctica's floating ice shelves, which form as the ice sheet extends into the Southern Ocean, influences how quickly grounded ice flows into the ocean. Estimating future sea‐level change from grounded‐ice loss therefore requires understanding, and developing models for, the processes that affect ice shelves. We used measurements of surface height from NASA's recently launched ICESat‐2 mission to explore one such process, the calving of small icebergs due to upper‐ocean melting of the ice front. We focus on the large Ross Ice Shelf. This local melting leads to bending of the ice shelf that can be seen in ICESat‐2 profiles that cross the ice front. The bending may also fracture the ice shelf to create small icebergs. We found that these surface structures are generally larger on the eastern portion of Ross Ice Shelf than on the western portion. We suggest that this pattern is due to differences in ice, ocean, and sea ice conditions that promote or impede the melting responsible for the ice‐shelf bending. ICESat‐2 will allow us to monitor changes in these small‐scale structures and any associated calving events, which will provide clues about how ice shelves will change in the future. Key Points: We used ICESat‐2 laser altimetry to map prevalent rampart‐moat (R‐M) structures along the Ross Ice Shelf front R‐M structures indicate a submerged buoyant bench seaward of the aerial ice front and ice stresses that may cause small‐scale calving Along‐front variation of R‐M height differences provides insight into sensitivity to oceanic and glaciological conditions