A study of the eddy kinetic energy of the Southern Hemisphere during January and July with emphasis on the FGGE year

The eddy kinetic energy (EKE) of the Southern Hemisphere was studied for January 1979 and July 1979 in terms of zonal wavenumber using the FGGE analyses of the European Centre for Medium Range Weather Forecasts. The EKE, the production of EKE, the transfer of EKE to the zonal mean, and the transfer of energy among waves by non-linear interactions were computed for wavenumbers from 1 to 10. In January, the EKE was a maximum at wavenumber 5 and in July it was a maximum at wavenumber 1 with a secondary maximum at wavenumber 5. In these 2 months and 10 wavenumbers, the major source of energy in the hemispheric EKE budget was the conversion of EAPE to EKE which had maxima at wavenumber 5. In general, each of the wavenumbers transfers energy to the zonal mean with the maximum at or near wavenumber 5. In January, the non-linear interaction term is a source of energy in the medium scales and a sink of energy in shorter and in longer scales while the opposite was the case in July. Some of the above calculations were done for an average of 5 Januaries and 5 Julys using the global analyses of the US National Meteorological Center and the character of the energy cycle revealed by the high quality FGGE data set was also evident in the operational analyses.