Numerical Experiments on the Generation of Normal Mode Rossby Waves

s Normal mode Rossby waves are simulated with an efficient Double Fourier Series (DFS) spectral model, and their structures are investigated by the Empirical Orthogonal Function (EOF) analysis. By selecting appropriately the wave-vector component for EOF analysis among the geopotential height and velocity fields of wavenumber one, it was possible to get the EOFs from the time series data whose spatial structures closely resemble the gravest three normal-mode waves. It was found that the leading modes of EOFs showed the phase configuration that tilts northward-westward and upward-westward in the horizontal and vertical plane, respectively. This indicates, as in the previous studies, that the normal mode Rossby waves are generated by the wave source in the lower atmosphere of southern-hemisphere high-latitudes. The wave amplitude of the temperature field that was obtained from the hydrostatic equation was shown to increase with the altitude except the upper tropospheric layers.