Ventilating the Deep: Quantifying pathways of deep ocean ventilation from ocean observations*

Deep ocean ventilation is controlled by the physical processes at high latitudes that allow for the formation and export of dense water masses. Here we review the observational evidence of the volume and pathways of deep water from the North Atlantic and Antarctic Seas, including inferred estimates from deep ocean properties and tracers as well as direct observations from limited moorings and process studies. In addition, any observational evidence of temporal variability over the last four decades from observations will be summarized.