My research

I use theory, numerical models, and observations to improve our understanding of ocean dynamics and the climate system.

Response of the Southern Ocean to changing winds

Because the Southern Ocean wraps all the way around the globe without being blocked by continents it has very different dynamics to the other oceans. The Southern Ocean connects the other oceans to each other, and is where much of the communication between the abyssal ocean and the atmosphere occurs. I’m using models and observational data to improve our understanding of how the Southern Ocean responds to changes in the winds.

You can read more about this work here and here.

Below is an animation of an idealised channel model simulation that spans several years of model time. You can see the sea ice expand and retreat during the year, and the way it interacts with the eddies.

Ocean dynamics in the Arctic

The complex interplay between ocean, sea ice, and atmosphere makes the Arctic a challenging an exciting region to study. Together with my colleagues I am helping to improve our understanding of ocean dynamics in the Arctic. We proposed a novel mechanism that may regulate the ocean currents in the Beaufort Gyre, and called it the Ice-Ocean Governor. We have also combined the Ice-Ocean Governor with previous theories that suggested eddies were responsible for controlling the circulation in the the Beaufort Gyre, producing a holistic framework that provides new insights into this region.

three-way-balance-chematic
The Ice-Ocean Governor and eddy fluxes balance the wind forcing in the Beaufort Gyre. The Ice-Ocean Governor regulates the Beaufort Gyre by increasing the momentum transfer into the ocean when the gyre is spinning slowly, and decreasing the momentum transfer when the gyre is spinning quickly.

Overturning circulations in wind-driven gyres

I’m examining the dynamics of wind-driven gyres through the use of a potential vorticity flux framework and Lagrangian particle tracking. The potential vorticity flux framework is described in Polton & Marshall (2007). Recent results show a dynamical balance in which an eddy induced overturning circulation largely opposes for the Eulerian mean overturning circulation. Lagrangian particle tracking techniques reveal that the downwelling observed in the Eulerian mean velocity fields is suppressed in the full time-varying velocity fields. You can read papers describing this work here and here.