| The increasing scope of environmental problems induced by human activities necessitate the enhancement of our knowledge about how the natural systems, such as the atmosphere and the oceans, function and interact with one another. In this thesis, we investigated some basic, yet still poorly understood aspects of the North Atlantic circulation. The ocean is modeled via two-layer, quasi-geostrophic dynamics.;The influence of atmospheric cooling on the separation latitude of the Gulf Stream is investigated. The buoyancy forcing is shown to cause the modeled Gulf Stream to separate from the coast with no overshooting, and at the correct latitude, if there exists a tendency toward increasing cooling at higher latitudes.;Finally, the effect of buoyancy forcing on the path of the Gulf Stream is explored using an analytical model. The governing equation for the path of the Stream is derived for simplified wind forcing. It is demonstrated that atmospheric cooling displaces the Stream to the south of the path predicted from purely wind-driven theory. For both simplified and more realistic wind forcing, the analytical model shows good agreement with the numerically-simulated path of the Gulf Stream.;The impact of the air-sea heat flux on the Gulf Stream system is explored. It is found that the buoyancy forcing plays an important role in the vertical distribution of the flow and the energy in the interior of the Subtropical Gyre. It is concluded that the intensity of the recirculation, and hence the transport of the Gulf Stream are strongly controlled by the small heat fluxes acting on the interior portion of the gyre, rather than the large cooling rates in the recirculation region. An analytical solution is developed to determine the distribution of the mean interior flow in each of the two layers. |
