This research will explore the decadal-scale interannual variability of the stratosphere, with the goal of increasing our understanding of the effects of both internal and solar-driven interannual variability and how these signals propagate through the atmosphere. Several signals or forcings have been identified which may account for many of the year-to-year changes in the stratospheric circulation. These signals include the quasi-biennial oscillation of the tropical stratosphere, the 11-year solar cycle, secular trends (possibly due to global climate change), El Nino/Southern Oscillation and tropospheric signals, and low-frequency modulation of higher-frequency signals. The approach will be to use a combination of observational data analysis and numerical modeling to explore the existence, causes, and propagation of decadal-scale signals in the stratosphere. Observational work will exploit gridded atmospheric data sets, rocketsonde observations, and satellite- and ground- based ozone measurements. Techniques such as correlations, composites, and empirical orthogonal functions will be used to identify interannual signals in the data. The effect of changes in solar output on the earth's recent climate is not well known. Likewise, decadal variations of the earth-atmosphere system apart from solar influence are poorly understood. The understanding of the interannual variability of the stratosphere is important not only because of its links to the troposphere, but due to possible identification of secular global climate trends and the role of solar variability in determining the global climate. #
