Stratosphere-troposphere Interactions

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

The role of annular modes in the dynamics of climate variability will be investigated, focusing especially on (i) the dynamical mechanisms by which changes in the structure and circulation of the stratosphere can affect the tropospheric zonal flow, and thence surface climate, (ii) the role that tropospheric and stratospheric eddy feedback processes play in the dynamics of this interaction, and (iii) the applicability of the fluctuation-dissipation theorem to the understanding of the response of the zonal flow to external perturbations. While this investigation is part theoretical analysis, the bulk of the research will comprise suites of experiments in a simplified stratosphere-troposphere general circulation model. Future experiments will include surface topography, in order to ensure a realistic level of stratospheric Rossby wave activity, as well as a realistic degree of non-zonality in the model climate. These studies will further understanding of atmospheric annular modes, and identify the processes that may provide sufficient coupling to lead to significant stratospheric influences on the troposphere. Broader impacts of this research are for the practice of climate modeling: if modeling the stratosphere correctly is an important prerequisite to modeling surface climate, there are important implications for climate models. Further, this work will have implications for the understanding of the dynamical impact of imposed perturbations, especially of increasing greenhouse gases and ozone depletion on climate.