Variability of local gravity wave spectra from data of a high-resolution icosahedral-grid global model

Abstract

Atmospheric gravity waves influence the general circulation through transport of energy and momentum. Even with increasing computing capacities, parametrisation of their effects is still needed. Here, we diagnose gravity wave spectra from the data of a high-resolution ICON simulation on subdomains defined by a low-resolution ICON grid. A unique methodology is applied that avoids unnecessary interpolations and filters the data by projection on the linearised gravity wave modes, providing precise and detailed information about the gravity wave spectra. The dependence of these spectra on latitude is then studied, highlighting the importance of the zonal wind direction in the shape of the spectra. Finally, we see that the spectra can be highly simplified by using tens to hundreds of principal components, which is a key property allowing for an increase in efficiency of current gravity wave parametrisations.