LAUSR

This paper analyzes the variability of the zonal cospectrum of Southern Hemisphere tropospheric eddy heat flux in reanalysis data. It is shown that the reduced spectral power of low-frequency eddy heat flux variability largely arises from the anticorrelation in the eddy heat transports by different zonal wave numbers. Although the most plausible mechanism for this relation invokes baroclinicity as a mediating agent, this hypothesis does not seem to be supported by the observed variability of baroclinicity. Low-frequency baroclinicity variability is primarily driven by the mean meridional circulation, with only a minor role for the eddy heat flux.