Summary
We describe a preliminary analysis of small-scale temperature perturbations in the stratosphere produced by long wavelength gravity waves, as measured globally during the CRISTA-SPAS missions. We focus on enhanced activity observed at the equator and near the southern tip of South America. Global ray-tracing simulations for the mission days indicate that the equatorial activity is broadly consistent with the transmission of nonzero phase speed waves into the stratosphere. Ray-tracing and mountain wave model simulations indicate that the activity over South America is produced by long wavelength mountain waves forced by flow over the Andes. The results suggest that the study of global gravity wave ‘weather’ in the middle atmosphere may soon be feasible.