9708194 Robinson Dr. Robinson will study stratospheric planetary waves - their variability, spectra, and interactions with the zonal flow - using a stochastically forced linear model. This approach, which recently has been successfully applied to tropospheric storm tracks, will permit the PI and colleagues to examine the influence of tropospheric and stratospheric zonal flows and stationary planetary waves on a full and unbiased spectrum of transient and traveling stratospheric waves. Specific issues that will be explored are: (1) the relative importance of transient and stationary wave activity in driving the zonal flow; (2) the extent to which stratospheric wave activity is controlled by stratospheric and tropospheric zonal flows, and the importance of interannual variability of the zonal flow in determining interannual variability in wave activity; (3) the importance of wave-wave interactions in regulating stratospheric wave activity; and (4) the expected interannual variability in wave-driving and the zonal flow in the absence of interannually varying boundary conditions. Dr. Robinson is a theoretician with a history of effectively employing linear theory in the study of atmospheric dynamics. He will evaluate the success of this approach by comparing his theoretical results with observations. This award is supported jointly by the Climate Dynamics and Large-scale Dynamic Meteorology Programs.