OBSERVED SOUTHERN HEMISPHERE EDDY STATISTICS AT 500 mb - FREQUENCY AND SPATIAL DEPENDENCE.

Abstract

Nearly eight years of daily Southern Hemisphere analyses at 500 mb have been used to define the spatial dependence of the variance fields of geopotential height and the two geostrophic wind components, the corresponding covariance fields, and the transient kinetic energy. The fields are further examined in the frequency domain by using E. N. Lorenz' ″poor man's spectral analysis″ technique. Results for the zonal mean statistics are compared with those from previous studies. The geographical dependence of the eddy statistics is mapped for four broad frequency bands covering periods of roughly less than one week, one week to two months, two months to two years, and greater than two years, thereby separating out contributions from transient baroclinic eddies, episodes of blocking, and intermonthly and interannual variability. The spatial patterns of the statistics are interpreted in the light of synoptic behavior of systems and storm tracks as defined by synoptic studies and satellite observations in the Southern Hemisphere.