The Seasonal Variation of Tropical Transient Planetary Waves Appearing in a GFDL General Circulation Model

Abstract

The seasonal variation of tropical transient planetary waves appearing in an 11-layer GFDL general circulation model is investigated. Space-time power spectra are estimated for every month by use of the maximum entropy method which can be applied to a short time record. The identification of equatorial wave modes is confirmed by space-time rotary spectral analysis which resolves traveling vortices into clockwise and anticlockwise components as well as eastward and westward moving components. It is found that the model's stratospheric Kelvin and mixed Rossby-gravity waves attain their primary and secondary maxima around July and January, respectively.