University of Reading, PO Box 239, Reading RG6 6AU, UK.
BEWARE: This page in still being developed. Some links may not exist and it
may change suddenly!
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:
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The dynamical regimes of global atmospheric circulation, including the
sensitivity to various imposed parameters.
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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.
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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.
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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.
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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.
This page is maintained by I.N.James@rdg.ac.uk