THE OBSERVED LIFE CYCLE OF A BAROCLINIC INSTABILITY


W. J. Randel and J. L. Stanford, Department of Physics and Astronomy, Iowa State University, Ames, IA 50011


J. Atmos. Sci., 42, 1364-1373 (1985)


Abstract

Medium-scale waves (zonal wavenumbers 4-7) frequently dominate Southern Hemisphere summer circulation patterns. Randel and Stanford have studied the dynamics of these features, demonstrating that the medium-scale waves result from baroclinic excitation and exhibit well-defined life cycles. This study details the evolution of the medium-scale waves during a particular life cycle. The specific case chosen exhibits a high degree of zonal symmetry, prompting study based upon zonally averaged diagnostics. An analysis of the medium-scale wave energetics reveals a well-defined life cycle of baroclinic growth, maturity, and barotropic decay. Eliassen-Palm flux diagrams detail the daily wave structure and its interaction with the zonally-averaged flow.