Atmospheric and geophysical fluid dynamics

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The research for which this proposal seeks continuing support addresses issues in mathematical geophysics on the one hand and in the fluid mechanics of atmospheric, oceanic and solid Earth processes on the other, areas that intersect in work on climate dynamics and climate system history. An example of such intersection is embodied in the unique theory I have developed to describe the deformations of planetary shape and accompanying variations in sea level caused by the Late Quaternary glacial cycle. The predictions of this model have been dramatically confirmed by the time-dependent gravity field observations provided by the GRACE satellites that remain in space. A further refined version of the model is being produced for the Paleoclimate Modelling Intercomparison Project (PMIP3) in work leading to the next IPCC report. This will include an improved representation of the depth dependence of mantle viscosity and a better constrained model of Eurasian deglaciation. The data sets produced will be employed by my own group and internationally in new coupled simulations of climate variability from Last Glacial Maximum to Holocene. Production work is also beginning on application of the now complete new three dimensional spherical numerical models of the general circulation of the mantle of the Earth and the atmospheric weather layers of the Gas Giant planets, the former directed towards improving our understanding of the impact of pressure induced phase transitions on the radial mixing length, and the latter towards providing an understanding of the origin and stability of the zonal jets that dominate the pole-to-pole variations of mean-flow velocity observed to characterize these objects. This work on Gas Giant zonal flows is leading towards the development of a new non-hydrostatic dry dynamical core that may be substituted for those used in more conventional atmospheric GCM's. On smaller spatial scales and in the area of pure fluid mechanics, I have begun a new project on the efficiency with which fully three-dimensional turbulence may act non-diffusively in mixing a mean density stratification, work that speaks to the way in which such turbulent processes should be "parameterized" in large-scale models.