Wavenumber frequency spectra of the meridional transport of sensible heat in the mid-troposphere of the Southern Hemisphere

Abstract

The wavenumber-frequency spectra of the meridional transport of sensible heat at 20°, 30°, 40°, 50°, 60°, and 70°S, at 500 mb in the Southern Hemisphere, show a definite spectral domain for the transport at various latitudes, which is dominated by the wave motion of the meridional component of the velocity. In middle latitudes, the spectral band of the meridional flux of sensible heat is oriented from a region of low wavenumbers and low frequencies to a region of high wavenumbers and negative frequencies assigned for waves moving from west to east. In low latitudes, the spectral band is confined to a narrow band centered near the zero frequency. It is found that most of the meridional transport of sensible heat at 500 mb in the Southern Hemisphere is accomplished by waves of medium wavelengths moving from west to east in middle and high latitudes. The meridional flux of sensible heat at 500 mb in the summer of the Southern Hemisphere is about three times that in the summer of the Northern Hemisphere. However, the meridional flux of sensible heat at 500 mb is about the same in the winter of both hemispheres. In the Southern Hemisphere practically all the meridional flux of sensible heat is associated with the moving waves in all seasons, whereas in the Northern Hemisphere the stationary waves contribute about 40% of the transport in winter.