Planetary waves modulated by the quasi-biennial oscillation (QBO)
Résumé
A qualitative analysis of the initial zonal conditions in terms of quasi-geostrophic refractive index can provide a fairly good understanding of the effect of the equatorial QBO in the stratosphere before a sudden warming. The prewarming evolution of the stratosphere has been simulated with a global 3-D numerical model in which several patterns of stratospheric equatorial winds have been injected. For each case of QBO, two different runs were performed with wavenumber 1 tropospheric perturbations of 200 and 300 gpm of the geopotential heights at 60 deg N at the lower level and referred to as F200 and F300, respectively. Special emphasis was given to such pre-warming conditions as the effect of the QBO on the quasi-geostrophic refractive index and the consequences for the propagation of planetary waves. The results of the sumulations were compared with those of previous experimental and theoretical research.