Tidal- / eddy-driven circulation and heat transfer on the continental shelf of Antarctica
In recent decades the Southern Ocean has increasingly been identified as a pivotal component of the climate system, notably via its role in closing the global meridional overturning circulation. This outsized influence is further exaggerated in the waters of the Antarctic continental shelf: export of dense shelf waters fill over 1/3 of the global sub-surface ocean, and heat supplied by warmer shelf waters is the primary cause of mass loss from the continental ice sheet. Despite their importance, scientific progress in understanding Antarctic continental shelf and slope processes lags far behind that of the broader Southern Ocean due to sparse observations and computational modeling constraints. This seminar will survey globally influential ocean and ocean/ice dynamical processes at the Antarctic margins, with an emphasis on the exchanges of water masses and heat between the open ocean and the continental shelf. We present recent insights from a very high-resolution global ocean/sea ice simulation, which we use to quantify the contribution of high-frequency flows to cross-slope exchanges around the entire continent for the first time. We show that both mesoscale eddies and ocean tides play central roles transferring heat toward the continent, and in driving the circulation along and across the continental shelf and slope. Our findings imply that these high-frequency flows fundamentally change the properties of the dynamical “barrier” between the open ocean and the Antarctic continental shelf. This poses a challenge for future observational deployments and modeling efforts, and for predicting the sensitivity of Antarctic shelf processes to climate shifts.