Abstract ATM-9526030 Webster, Peter J. University of Colorado Title: The Dynamics of Low-Frequency Phenomena The PI will investigate and describe: o The morphology of the monsoon and its relationship with other circulation systems. This project represents a major new initiative in the study of low frequency phenomena. o Wave propagation through the very complex background flow of tropics. The PI plans to extend earlier work and to investigate the impact of vertical shear on equatorial wave propagation and, finally consider all shears and stretching deformations concurrently. o Intraseasonal variability from the perspective of coupled ocean-atmosphere dynamic systems. The PI notes that the location of convection in the tropics and its organization on the intraseasonal time scales remains largely unexplained. He plans to investigate this organization from a fundamental perspective relative to the coupled ocean-atmosphere system. The monsoons and the circulation associated with the east-west sea- surface temperature (SST) gradients produce a slowly evolving system within which resides a large proportion of the interannual variability of the climate system. The slow migrations of convection clusters which make up the intraseasonal variability in the tropics may be products of the low frequency monsoon-ENSO system. To a first approximation, the regions where equatorial transient waves accumulate their energy or where they influence higher latitudes is determined by the slowly evolving state of the monsoon-ENSO system. The PI proposes a program in which the low frequency monsoon-ENSO systems is defined within the context of ocean-atmosphere-land coupling. This research is important because it seeks knowledge about the factors that control the seasonal-to-interannual variability of the climate. Such knowledge is required in order to improve the prediction of climate variability on these time s cales.
