Collaborative Research: Dynamics and Transport of the Antarctic Circumpolar Current in Drake Passage (cDrake) Analysis

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The Southern Ocean, dominated by the huge Antarctic Circumpolar Current (ACC), is responding markedly to climate change, being driven by circumpolar winds that have increased over the past ~30 years, and warming significantly more that the global ocean over the past ~50 years. Geographically, the Drake passage provides a natural ?chokepoint? for measuring the time varying transport of the ACC component flows. In turn this provides us with a means of taking the ?pulse? of the Southern Ocean circulation. The cDrake field experiment is an IPY project to resolve seasonal to interannual variability of the ACC over a four year period. Using an array of (~40) bottom-moored Current and Pressure-recording Inverted Echo Sounders (CPIES) which measure bottom pressure along with the travel time of 12kHZ sound pulses to and from the surface, a time series of velocity and temperature profiles over a grid array has been assembled over a 5 year timespan. A full analysis of the CPIE and ancillary hydrographic data sets (e.g. CTD, ADCP and XBT) will be undertaken to resolve the ACC transport variability, partition its vertical structure between barotropic and baroclinic components, and its lateral structure partitioned between the many jets and fronts that comprise the ACC in the Drake Passage.