Basal channels affecting oceanic melting and freezing of a rifted Antarctic ice shelf

• Main Author: Nanninga, Stefanie (author)
• Other Authors: Poinelli, M. (mentor), Vizcaino, M. (mentor), Katsman, C.A. (graduation committee), Delft University of Technology (degree granting institution)
• Format: Master Thesis
• Language: English
• Published: 2022
• Subjects: basal melt channels; rift; ice shelf; Antarctic Ice Sheet; cavity circulation; MITgcm; Antarctic; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves; Iceberg*
• Online Access: http://resolver.tudelft.nl/uuid:4dda5905-3fca-4314-8933-fe74f2ee1be0

Floating ice shelves regulate Antarctic ice sheet mass loss by buttressing land ice discharge toward the ocean. Next to basal melting, iceberg calving following the propagation of rifts has the potential to reduce this buttressing effect. However, rift propagation is largely unpredictable and generally not resolved in coarse climate models. The sub-shelf ocean circulation is believed to play an important role in rift propagation as it is closely related to ice shelf melting and freezing. Previous work suggests that the sub-shelf circulation of an intact ice shelf is altered by the presence of km-wide basal channels. As it could impact freezing and melting, the potential effect of basal channels on a rifted Antarctic ice shelf should be explored. In this study, the Massachusetts Institute of Technology general circulation model was applied to explore for the first time the potential effect of basal channels on the melting and freezing of a rifted Antarctic ice shelf. To this end, four simulations were performed with a high-resolution ocean model for the domain of an ice shelf cavity with idealized boundary conditions. These simulations correspond to a cavity with melt channels, a prominent rift close to the ice shelf front, both, and none of them. The effects of channels, a rift or the combination of both on melt, freezing and ocean circulation in the cavity were assessed through a comparison of these four simulations. Following previous research, results show that basal channels decrease ice shelf basal melting. We found that the addition of only a rift does not change the melt intensity or pattern. In addition, it was found that basal channels increase the freezing inside a rift. A sub-shelf boundary current on the Coriolis favoured side of the domain without channels is reformed to a clockwise circulation in each channel, resulting in an adjusted flow pattern inside the rift from one single large clockwise return flow to a smaller one behind each channel. Hence, buoyant cold shelf meltwater does not only enter ...