The effects of thermodynamic parameterizations, ice shelf geometry, and tides on modeled basal melting of Weddell Sea ice shelves

• Main Author: Mueller, Rachael D.
• Other Authors: Padman, Laurence, Skyllingstad, Eric, Fricker, Helen, A., Ruggiero, Peter, Samelson, Roger, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University. Graduate School
• Format: Doctoral or Postdoctoral Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Ice shelves > Antarctica > Weddell Sea; Thawing > Antarctica > Weddell Sea; Meltwater > Antarctica > Weddell Sea; Antarc*; Antarctic; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves; Sea ice; Weddell Sea
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/3x816s04t

Antarctic Ice Sheet mass balance and, hence, sea level change is affected by the floating extensions of outlet glaciers and ice streams that take up about 44% of the coastline (Drewry et al., 1982) and are referred to as "ice shelves". Ice sheet mass loss accelerates when these ice shelves lose mass through basal melting at the ice-ocean interface or calving along the ice shelf front. The focus of this dissertation is to explore the uncertainties in basal melt predictions, as affected by ocean temperatures, ocean currents, and model geometries. Uncertainties in tidal currents and the corresponding affect on sub ice shelf basal melt was explored using the Regional Ocean Modeling System (ROMS 3.2), adapted to represent the thermodynamics of ice shelf basal melt at the ice/ocean interface. Plausible representations of present and future sub ice shelf topographies were used to explore potential errors in tidal forcing and ocean circulation beneath the Larsen-C and Filchner-Ronne ice shelves of the Weddell Sea, Antarctica. The influence of thermal forcing and thermodynamic parameterizations was also explored. The results presented here demonstrate that two plausible Larsen-C Ice Shelf (LCIS) topographies could yield shelf-averaged basal melt rates that differ by nearly a factor of two. The difference in these two cases is due to regional variations in tidal currents. The standard grid topography, based on realistic modern bathymetry and ice draft, supported topographic vorticity waves at diurnal frequencies in the northeast LCIS while an alternate model geometry did not. As such, these two grid topographies not only affected the shelf-averaged value of basal melting but also the regional variation in basal melting. Regional variation is important because it determines whether basal melting will have a greater impact on the rate at which ice moves off-shore, as in grounding line melt, or the rate of calving, as in melting along the ice shelf front. Out of all parameterizations, grounding line melt is shown to be ...