Transient Planetary Waves Simulated by GFDL Spectral General Circulation Models. Part I: Effects of Mountains

Abstract

Space-time spectral analysis over a three year data set is made of transient planetary waves simulated by Geophysical Fluid Dynamics Laboratory (GFDL) spectral general circulation models with and without mountains. In both models westward moving ultralong waves have larger geopotential amplitude than eastward moving ultralong waves, being in agreement with observations. In both models westward moving ultralong waves are associated with little vertical tilt and a large meridional wavelength, while eastward moving ultralong waves are associated with some vertical tilt and a small meridional wavelength. In the absence of mountains westward moving ultralong waves are somewhat decreased, while eastward moving ultralong waves are somewhat increased, and eastward moving wavenumber 4?6 components are markedly increased in the Northern Hemisphere.