I am interested in the general circulation of the atmosphere at large scales. Topics that I work on include:
- The cause of the projected poleward shift of the westerlies in greenhouse-warmed climates.
- The dynamical mechanism for the dominance of the annular modes - that is the north-south vacillation of the westerly wind belts about their climatological position.
- Evaluating the accuracy of GCMs such as those used in the IPCC climate change assessment reports, and trying to understand where and why the models differ from reality.
- The climatological control on the atmospheric eddy length scale, and the cause of the projected increase in the eddy length scale under increased greenhouse gasses.
- The cause of the relationship between the latitude and the persistence of an eddy-driven jet.
- The cause of the relationship between the latitude and the width of an eddy-driven jet.
- The dynamics of the seasonality of the annular mode in the southern hemisphere.
- The dynamical mechanism behind tropical-extratropical interactions - how the mid-latitude eddy-driven jet streams are affected by the El Nino southern oscillation.
To do this I use a range of tools and approaches. These include the analysis of observational data in (hopefully) new and interesting ways; evaluating the dynamics of fully comprehensive GCMs; and using simplified models to test and understand basic dynamics.
Simplified models are an important tool in large scale climate dynamics. They are often the only effective way to isolate the process that is of interest. The goal is usually to find the simplest framework that reproduces the phenomenon of interest. If the dynamics can be understood in the most simple case, an investigation can then be made into whether they are relevant to more realistic situations.