Analyses of Large-Scale Climate Variability

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The project will use both numerical experiments and observational analyses to investigate two unsolved questions in the field of climate dynamics: 1) what physical mechanisms drive the tropospheric response to extratropical stratospheric variability? and 2) through what processes do anthropogenic emissions of carbon dioxide and ozone depleting gases drive large-scale changes in the extratropical circulation? In the modeling component, the investigators will examine and diagnose the simple general circulation model response to spatially varying thermal forcings which mimic the radiative responses to increasing atmospheric carbon dioxide and stratospheric ozone depletion/recovery. The experiments will be used to 1) assess the circulation responses to thermal forcings at tropospheric and stratospheric levels; 2) assess the robustness of the responses to changes in the shape and amplitude of the forcings and to changes in the model climatology; and 3) investigate the physical mechanisms that drive the simulated responses. In the observational component, the investigators will conduct analyses that 1) complement the numerical experiments, and 2) investigate the processes associated with recent stratospheric climate change. The observational analyses will provide a "reality-check" for the model experiments, new analyses of the daily evolution of the heat and momentum fluxes associated with stratosphere/troposphere coupling, and new analyses of the linkages between tropical tropospheric heating and variability in the extratropical flow.The broader impacts of this work include implications for weather forecasting (via stratosphere/troposphere coupling), for the attribution of past climate trends, and for the prediction of future changes in the circulation in response to anthropogenic forcing. This project will train and support one postdoctoral researcher and two graduate students.