Low-frequency Variability in the Extratropical Atmosphere

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This award provides support for continued research into the dynamics of intraseasonal variability of the midlatitude atmosphere. Dr. Robinson employs highly idealized models of the atmosphere, in this case a single level barotropic model on a sphere, which allow him to isolate and study fundamental processes of the atmosphere. Under his previous award, Dr. Robinson and his student developed a new version of the barotropic model that incorporates information about the scale-dependent vertical structure of atmospheric eddies. The model now will be tested by doing hindcasts of episodes of low frequency variability. The dynamics of the model will be examined using several different approaches. The role of transient-eddy forcing for low frequency variability will be diagnosed by forcing the model with observed transient-eddy potential vorticity fluxes. Dr. Robinson hopes to demonstrate that, with the vertical structure eddy information, the simple model will agree quantitatively with observations, thus providing confidence that the conceptual insights gained with the idealized model are relevant to the real atmosphere.