Rates and Mechanisms of Turbulent Mixing in a Coastal Embayment of the West Antarctic Peninsula

Quantifying and understanding the processes driving turbulent mixing around Antarctica are key to closing Southern Ocean's heat budget, an essential component of global climate system. In 2016, a glider deployed in Ryder Bay, West Antarctic Peninsula, collected hydrographic microstructure data, obtaining some first direct measurements kinetic energy dissipation off Antarctica. Elevated O(10−8) W kg−1 is found above topographic ridge separating 520-m-deep bay, where values O(10−10) kg−1, from deep fjord continental shelf, suggesting important upward warm Circumpolar Deep Water. The 12 transects reveal significant temporal variability conditions. Mooring-based current nearby meteorological data used attribute thermocline shoaling (deepening) Ekman upwelling (downwelling) at Bay's southern boundary, driven by ∼3-day-long south-westward (north-westward) wind events. Anticyclonic winds generated near-inertial shear bay's upper layers, causing elevated bay-wide ∼1.7 days later. High over appears be controlled hydraulically, being co-located (and moving) with steeply sloping isopycnals. These observed ∼60% transects, corresponding mean flux ∼2.4 m−2. ridge, therefore, provides sustained base thermocline, which can released into overlying waters during bay-wide, thermocline-focused events (mean ∼1.3 m−2). This highlights role ridges, widespread across regional budget.