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Ian James' Research Page

Our research group is linked in to the UGAMP programme, Most of my current research, and that of my research students, centres around the transient baroclinic eddies of the midlatitudes, their structure, lifecycles and the way in which they affect the time and/or zonal mean flow. A basic research tool is the "Simplified Global Circulation Model" or SGCM, which retains full dynamical complexity of a sprectral primitive equation model, but which greatly simplifies heating and friction processes. The latter are represented by linear relaxation terms. The model has no moisture, no orography and no variation of surface properties, though these restrictions have been relaxed in various PhD projects. Using this model, various lines of enquiry are being pursued:
• The dynamical regimes of global atmospheric circulation, including the sensitivity to various imposed parameters.

• The internal, low and very low frequency variability of the atmospheric circulation. Early work with the SGCM revealed just how variable certain aspects of its circulation, especially the zonal mean, zonal wind can be, with significant variability on times of years or even decades. Understanding the mechanisms for this variability and its sensitivity to the imposed parameters and the form of the circulation are an essential element in using GCMs for climate change studies.

• The parametrization of baroclinic eddies. That is, if the mean state of the the atmosphere is given, can the strength and transport properties of the transient eddies be inferred. This is more than a technical problem of designing a faster form of model. All attempts at "understanding" the global circulation and its time and spatial variations involve explicitly or implicitly an attempt to parametrize the eddies in this way.

• The circulation of the atmosphere around Antarctica has a number of interesting and unique features. Antarctica is an important source of long Rossby waves for the Southern Hemisphere, while the precipitation over the ice sheet depends upon the lifecycles and tracks of cyclones around the edge of the continent. The persistent drainage flow, especially in winter, makes a major contribution to the high latitude global circulation.

• No-one wants to fund research into planetary atmospheres, but the fact that such studies are now possible is a mark of the maturity of our subject. We are no longer restricted to considering the circulation of the Earth's atmosphere, but rather we see the Earth in the context of a comparative study of the circulation of a range of planets. We have studied the predictability of the Martian atmosphere, the effects of strong seasonality (Uranus), and the role of surface drag (gas giants vs terrestrial planets). Other projects are taken up as funding opportunities permit.