General Circulation Studies

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The primary objective of this ongoing research project is to improve our understanding and prediction of atmospheric variability with time scales longer than a week. The research involves the diagnosis of observational and model generated data sets, using statistical techniques such as simple compositing, digital filtering in the time domain, principal component analysis and canonical correlation analysis, and emphasizing the dynamical interpretation of the results in light of our current understanding of large-scale atmospheric dynamics. The work is closely linked to projects in general circulation modeling at NCAR and NOAA/GFDL and to operational and experimental numerical weather prediction at NOAA/NMC and ECMWF. Fluctuations with periods on the order of weeks and longer are generated both by dynamical processes internal to the atmosphere and by interactions between the atmosphere and the underlying media (primarily the oceans and the land-surface hydrology). The relevant dynamics include a variety of processes that operate on low-frequencies, as well as the forcing by high frequency transients associated with baroclinic instability. By careful analysis of the spatial patterns and time sequences of time-filtered meteorological fields, the PIs hope to isolate the signatures associated with the various processes and document how they contribute to the total variability. This research is important because it contributes in a direct way toward our ability to predict atmospheric variability on time-scales relevant to human activities.