Middle atmospheric traveling waves forced by latent and convective heating

Abstract

The excitation and propagation of equatorial planetary waves and inertia-gravity waves were studied by comparing simulations from the comprehensive GFDL troposphere-stratosphere-mesosphere SKYHI general circulation model (GCM) and from a linear primitive equation model with the same domain and numerical resolution. The wavelength and frequency characteristics of the prominent vertically propagating equatorial Kelvin and Rossby-gravity waves are remarkably similar in the linear model and in SKYHI. At low latitudes the linear model reproduces the flux of upward-propagating inertia-gravity waves seen in the full model. A significant fraction of the inertia-gravity wave activity found in the midlatitude mesosphere of the SKYHI model can be accounted for by tropical convective heating. The global-scale Rossby normal modes seen in observations were also identified in the analyses of westward-propagating planetary waves in both models. They are of realistic amplitude in the SKYHI simulation but are much weaker in the linear model. Thus, it appears that latent and convective heating is not the main source of excitation for the Rossby normal modes. -from Authors