| Abstract: The mechanism of thermocline ventilation
is investigated using a global, high-resolution ocean GCM, with
realistic topography and surface wind forcing. Because
2-dimensional representations of circulation can be misleading, the
subsurface flow is examined by visualizing the trajectories of particles
with subduct in the mid-latitudes and travel within the ventilated
thermocline. Three model runs are performed, each with identical
surface forcing but with different initial particle distributions.
Results from these runs show that the pathways of water mass exchange
between the tropics and the subtropics are functions of the surface wind
forcing, background density structure, and basin geometry. In the
Pacific, ventilated waters from the northern and southern mid-latitudes
reach the tropical thermocline through both the western boundary and the
interior of the basin. In the Atlantic Ocean, the equatorial
thermocline is ventilated primarily through water mass exchange with the
southern hemisphere alone. In the Indian Ocean, the pathways of
water mass exchange have patterns similar to those in the Atlantic and
Pacific basins, though the lack of a mid-latitude gyre in the northern
basin restricts the deep subduction and ventilation to the southern
hemisphere. |