Variability of local gravity wave spectra

Gravity waves influence atmospheric dynamics through transport of momentum and energy, and their understanding is thus essential for improving their parametrisations in atmospheric models. In this work, we study gravity waves using data from a global ICON simulation with a horizontal resolution of approximately 2.5 km. The data are divided into triangular subdomains defined by a low-resolution ICON model grid, which has a horizontal resolution of about 160 km. We evaluate 3D spatiotemporal spectra within these subdomains and subsequently filter the spectra using linear gravity wave theory, yielding the global distribution of local gravity wave spectra. Analysis of the spectra reveals latitudinal dependence, with the zonal wind direction shaping the spectral form. Notably, spectra simplify dramatically using tens to hundreds of principal components, capturing variance efficiently. This approach enhances gravity wave parametrizations by providing low-dimensional spectral representations, enabling more accurate and computationally efficient global modeling.