Circumpolar Variability and Exchanges Across the Antarctic Slope Front

The Antarctic Slope Front (ASF) almost completely encircles the Antarctic continent, separating relatively cold shelf waters from warmer waters at mid-depth in the open ocean. It serves as a "gatekeeper" for waters intruding onto the Antarctic continental shelf, such as the warm Circumpolar Deep Water that supplies heat to melt the bases of Antarctica's ice shelves, and for waters escaping the continental shelf, such as the dense water outflows that fill more than one-third of the global sub-surface ocean. Practical constraints imposed by Antarctica's climate and the small scales of variability have limited previous quantification of cross-slope exchange processes to localized regions. There remains a substantial gap in understanding how continental-scale exchanges of water between the open ocean and the shelf seas are modulated by seasonal variability in atmospheric conditions, heterogeneous bathymetry, and small-scale/high-frequency sources of variability such as eddies, tides, overflows and topographic waves.

This project aims to close this gap in understanding by developing the first ocean/sea ice model simulations of the entire Antarctic margins, including the ocean beneath the floating ice shelves, that can resolve small-scale variability and tides. Using analysis techniques based on multiple separation of time scales, we are working to quantify cross-slope exchanges of mass and properties and thereby identify regimes in which the ASF serves as a "barrier" to or a "blender" of those properties. The project also encompasses a new educational initiative to engage hundreds of UCLA undergraduate students per year in research cruises to the local continental shelf and slope off the coast of California. A captain/technician will be recruited to facilitate dozens of cruises annually using the UCLA Zodiac research vessel. 

This work is supported by the National Science Foundation, grant number OCE-1751386.

A snapshot of ocean (potential) temperature at 230m depth around Antarctica, or at the ocean bed in locations where the ocean is shallower than 230m. This snapshot was taken from a global ocean/sea ice model simulation run at NASA Ames by D. Menemenlis (NASA JPL). For further information, see Stewart et al., Geophys. Res. Lett. 2018 on the Publications page.