Dynamics of Ocean
Currents and Fronts
Udintsev Fracture Zone
Across the Antarctic Circumpolar Current (ACC), fluxes of heat and momentum and other dynamical quantities establish the heat budget for the whole Southern Ocean, govern the strength of the ACC and its vital inter-ocean exchanges, and arguably govern the main vertical density structure of the world oceans. Yet, theoretical concepts, numerical models, and the sparse observational records give conflicting views of the mechanisms and magnitude of transfers across the ACC. South of about 55°S the puzzle is further confounded, because the heat fluxes associated with wind-driven Ekman transport and its counterbalancing meridional overturning circulation, that are strong and dominant at lower latitudes, become weak. At that latitude, it falls to cross-frontal processes arising from mean and eddying flow to complete the heat budget. It is particularly puzzling how fluxes cross the several ocean fronts, e.g., from Subantarctic Front to Polar Front to Southern ACC Front. Observations of heat and momentum fluxes and mixing are vitally needed at additional sites around the ACC to inform global climate modeling efforts. Of particular interest is how the oceanic meridional overturning circulation absorbs and redistributes heat and carbon that is critical to the earth's climate. In this study, an array of Current and Pressure recording Inverted Echo Sounders (CPIES) will be deployed for a period of two years to observe and quantify exchanges of buoyancy, heat, momentum and potential vorticity across the ACC as it flows near the Udintsev Fracture Zone in the central South Pacific sector of the Southern Ocean. The CPIES have been shown to be particularly well suited for these measurements. The Udintsev Fracture Zone has been selected because the three main fronts (Subantarctic Front, Polar Front, and Southern ACC Front) converge closely together as they deflect equatorward where they encounter complex shallower ridges and exhibit strong eddy variability in the lee. Therefore, the Udintsev Fracture Zone emerges as a likely location for mean and eddy fluxes to combine to cross the entire ACC system. This project is an international collaboration with a team of French and Korean scientists with complementary goals to deploy tall current meter moorings and conduct CTD surveys in this region.
UFZ is funded by the National Science Foundation under Award Number 1358470.
Disclaimer: Any opinions, findings and conclusions or recomendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).
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