A revised method of presenting wavenumber-frequency power spectrum diagrams

The popular method of presenting wavenumber-frequency power spectrum diagrams for studying tropical large-scale waves in the literature is shown to give an incomplete presentation of these waves. The so-called “convectively-coupled Kelvin (mixed Rossby-gravity) waves” are presented as existing only in the symmetric (anti-symmetric) component of the diagrams. This is obviously not consistent with the published composite/regression studies of “convectively-coupled Kelvin waves,” which illustrate the asymmetric nature of these waves. The cause of the inconsistency is revealed in this presentation and a revised method of presenting the power spectra is proposed. When this revised method is used, “convectively-coupled Kelvin waves” do show anti-symmetric components, and the “convectively-coupled mixed Rossby-gravity waves” do show a hint of symmetric components. These results bolster a published proposal that these waves be called “chimeric Kelvin waves,” “chimeric mixed Rossby-gravity waves,” etc. This revised method of presenting the power spectra offers an additional means of comparing GCM output with observations by calling attention to the capability of the GCMs to correctly simulate the asymmetric characteristics of the equatorial waves.