USAP-DC

Van der Veen/1543530

The objective of this research is to gain better understanding of the West Antarctic ice flow in the transition region from grounded ice to floating ice shelves and investigate the conditions that can initiate and sustain major retreat of these glaciers. Several major Antarctic outlet glaciers and ice streams will be investigated using a suite of observational techniques and modeling tools. Glaciers include Thwaites Glacier, which has become a focal point in the discussion of West Antarctic retreat, Whillans Ice Stream as an example of the archetype ice stream, and Byrd Glacier, a major outlet glacier draining East Antarctica through the Transantarctic Mountains into the Ross Ice Shelf. This study will investigate whether the ongoing changes in these glaciers will lead to long-term mass loss (the onset of ice sheet collapse), or whether these glaciers will quickly stabilize with a new geometry.

To adequately incorporate the dynamic behavior of outlet glaciers and ice streams requires inclusion of the relevant physical processes, and the development of regional models that employ a numerical grid with a horizontal grid spacing sufficiently refined to capture smaller-scale bed topographic features that may control the flow of these glaciers. This award revisits the issue of stability of marine-terminating glaciers whose grounding line is located on a retrograded bed slope. In particular, an attempt will be made to resolve the question whether observed rapid changes are the result of perturbations at the terminus or grounding line, or whether these changes reflect ice-dynamical forcing over the grounded reaches. High-resolution satellite imagery will be used to investigate ice-flow perturbations on smaller spatial scales than has been done before, to evaluate the importance of localized sites of high basal resistance on grounding-line stability. This collaborative project involves a range of modeling strategies including force-budget analysis, flow-band modeling, Full Stokes modeling for local studies, and using the Ice Sheet System Model developed at JPL for regional modeling. Broader Impacts include training two graduate students in computer simulations and ice sheet modeling algorithms. The work will also expand on a web-based interactive flowline model, so that it includes more realistic grounding line dynamics.

Person	Role
van der Veen, Cornelis	Investigator and contact
Stearns, Leigh	Co-Investigator
Paden, John	Co-Investigator

Antarctic Glaciology	Award # 1543533
Antarctic Glaciology	Award # 1543530

USAP-1543530_1

None in the Database

1. Stearns, L. A., and C. J. Van der Veen. "Friction at the bed does not control fast glacier flow." Science 361.6399 (2018): 273-277. (doi:10.1126/science.aat2217)
2. Downs, J., & Johnson, J. V. (2022). A rapidly retreating, marine-terminating glacier’s modeled response to perturbations in basal traction. Journal of Glaciology, 1–10. (doi:10.1017/jog.2022.5)
3. Downs, J. Z., Johnson, J. V., Harper, J. T., Meierbachtol, T., & Werder, M. A. (2018). Dynamic Hydraulic Conductivity Reconciles Mismatch Between Modeled and Observed Winter Subglacial Water Pressure. Journal of Geophysical Research: Earth Surface, 123(4), 818–836. Portico. (doi:10.1002/2017jf004522)
4. Meierbachtol, T., Harper, J., & Johnson, J. (2016). Force Balance along Isunnguata Sermia, West Greenland. Frontiers in Earth Science, 4. (doi:10.3389/feart.2016.00087)