The response of a thermocline gyre to anomalies in surface wind stress forcing and surface buoyancy forcing is investigated in light of planetary wave dynamics, both analytically and numerically. The author’s theory suggests that anomalous Ekman pumping most efficiently generates the non-Doppler-shift mode, which resembles the first baroclinic mode and has the clearest signal in the sea surface...

A stationary SST mode is proposed to understand the physical mechanisms responsible for the phase transition of the El Niño–Southern Oscillation. This stationary SST mode differs from the original delayed oscillator mode and the slow SST mode in the sense that it considers both balanced and unbalanced thermocline depth variations and does not take into account the zonal propagation of SST. With...

During November and December 1983, two anticyclonic eddies were observed west of the Agulhas Retroflection, apparently spawned at the retroflection. The western eddy, centered 300 kilometers southwest of Cape Town, has a winter cooled core encircled by warm Indian Ocean water. Between Cape Town and the "Cape Town Eddy" is a net geostrophic transport of Indian Ocean thermocline water (14 x 10(6)...

A current scenario to explain much of the atmospheric CO2 increase during the Glacial to Holocene climate transition requires the outgassing of a deep, old oceanic CO2 reservoir thought to be located in the Southern Ocean. In this scenario, CO2-rich and 14C-depleted subsurface Antarctic-sourced water, ventilates the thermocline where it is purged to the atmosphere in the equatorial regions, a v...

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 which subduct in the mid-latitudes and travel within the ventilated thermocline. Three model run...

A band of enhanced thermocline variability at 108–158N in the Pacific found in nature also occurs in an ocean general circulation model forced with observed fluxes of momentum, heat, and freshwater over the period 1958– 97. The variability in the model is primarily associated with long baroclinic Rossby waves characterized by periods in the decadal range (7–10 yr). The waves are forced by westw...

In this thesis, I study the time-varying behavior of a ventilated thermocline with basin scales at annual and decadal time scales. The variability is forced by three external forcings: the wind stress (chapter 3), the surface heat flux (chapter 4) and the upwelling along the eastern boundary (chapter 5). It is found that the thermocline variability is forced mainly by wind in a shadow zone whil...