Changes in the rate of ocean‐driven basal melting of Antarctica's ice shelves can alter the rate at which the grounded ice sheet loses mass and contributes to sea level change. Melt rates depend on the inflow of ocean heat, which occurs through steady circulation and eddy fluxes. Previous studies have demonstrated the importance of eddy fluxes for ice shelves affected by relatively warm intrusions of Circumpolar Deep Water. However, ice shelves on cold water continental shelves primarily melt from dense shelf water near the grounding line and from light surface water at the ice shelf front. Eddy effects on basal melt of these ice shelves have not been studied. We investigate where and when a regional ocean model of the Ross Sea resolves eddies and determine the effect of eddy processes on basal melt. The size of the eddies formed depends on water column stratification and latitude. We use simulations at horizontal grid resolutions of 5 and 1.5 km and, in the 1.5‐km model, vary the degree of topography smoothing. The higher‐resolution models generate about 2–2.5 times as many eddies as the low‐resolution model. In all simulations, eddies cross the ice shelf front in both directions. However, there is no significant change in basal melt between low‐ and high‐resolution simulations. We conclude that higher‐resolution models (<1 km) are required to better represent eddies in the Ross Sea but hypothesize that basal melt of the Ross Ice Shelf is relatively insensitive to our ability to fully resolve the eddy field.
Ocean heat supply to ice shelves has a significant impact on the long‐term evolution of ice shelves. Intrusions of warm surface waters into the frontal region of the cavity, known as “Mode 3” circulation, are capable of melting the ice shelf base. However, ablation of the vertical walls of the ice shelf front has, to date, received little attention. Here we propose a mechanism for Mode 3 circulation that is aided by ice shelf front ablation: Direct contact of warm Antarctic Surface Water with the ice wall generates meltwater that buoyantly ascends the vertical face and leads to formation of a “wedge” of fresher water immediately adjacent to the wall. This wedge, which thins with distance from the ice shelf front, allows isopycnals to curve gently downward, creating an efficient conduit by which surface waters moved by other forces such as tidal flow and eddies enter an ice shelf cavity with minimal mixing. Here we use new and existing observational data from the Ross Sea and the Ross Ice Shelf cavity to demonstrate the existence of the wedge. Our analysis and a review of the literature suggest that the freshwater wedge structure is a pervasive feature of the Western Ross Sea in summer and enhances other inflow mechanisms.
more » « less- PAR ID:
- 10460662
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Oceans
- Volume:
- 124
- Issue:
- 2
- ISSN:
- 2169-9275
- Page Range / eLocation ID:
- p. 1196-1214
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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