Gordon E. Swaters
The ocean is the regulator of Earth's climate. The world's oceans store an enormous
quantity of heat that is redistributed throughout the world via the currents. Because the
density of water is about a thousand times larger than the density of air, the ocean has a
substantial inertia associated with it compared to the atmosphere. This implies that it
takes an enormous quantity of energy to change an existing ocean circulatory pattern as
compared to the atmospheric winds. For this reason, one can think of the ocean as the
"memory" and "integrator" of past and evolving climate states.
Ocean currents can be characterized into two broad groups. The first are the currents
that are wind driven. These currents are most intense near the surface of the ocean.
Their principal role is to transport warm equatorial waters toward the Polar Regions (for
example, the Gulf Stream). The second are the currents that are driven by density
contrasts with the surrounding waters. In this latter group are the deep, or abyssal,
currents flowing along or near the bottom of the oceans in narrow bands. Their principal
role is to transport cold, dense waters produced in the Polar Regions equator ward (for
example, the Deep Western Boundary Current). Taken together, the pole-ward flowing
warm surface currents and equator-ward flowing cold abyssal currents comprise the
planetary-scale convective overturning circulation of the Earth's oceans.
My research group is working toward understanding the dynamics of these abyssal
currents. In particular, we have focused on developing mathematical and computational
models to describe the evolution, including the transition to instability and interaction with
the surrounding ocean, of these flows. The goal of this research is to better understand
the spatial and temporal variability of the planetary scale dynamics of the ocean climate
system. Our work can be seen as theoretical in the sense that we attempt to develop
new models to elucidate the most important dynamical balances at play and process-
oriented in the sense that we attempt to use these models to make concrete predictions
about the evolution of these flows. As such, our work is an interdisciplinary blend of
physical oceanography, classical applied mathematics and numerical simulations.
In this talk I will describe our efforts to understand the large scale dynamics and
evolution of these abyssal ocean currents. Along the way, various applied mathematical
themes will be touched on including physical modelling, asymptotic reduction,
Hamiltonian partial differential equations, variational methods and numerical simulations.
