Oceanic abyssal and thermocline flow in tracer space

Temperature, salinity and age provide a natural coordinate frame in which to understand the flow of oceanic waters: temperature and salinity help identify their sources while age gives information on their evolution. Here both idealized (simple gyre) and realistic global ocean models are diagnosed in this temperature-salinity-age space. Formation and modification of thermocline and deep waters is clearly elucidated within this framework, with the subduction and re-emergence of watermasses occurring in different regions in physical space with differently signed Jacobian of the transformation between physical and tracer spaces. Mixing processes are found to have a characteristic signature on flows as viewed in this framework.