This example couples 3D gravity‐wave dynamics with a simplified airglow chemistry model in the mesosphere and lower thermosphere. Background temperature and composition profiles are imported from external atmosphere models (e.g. NRLMSISE), and are then used to construct steady states for the major species \( (\text{O}, \text{O}_2, \text{N}_2, \text{O}_3) \) and the airglow emitters (OH vibrational levels, excited oxygen).

On top of this steady background, ExaHyPE 2 evolves a finite–volume Godunov solver that transports the chemical species with prescribed winds and applies height-dependent production and loss terms. Different sets of Einstein coefficients can be selected to study how the gravity waves modulate the airglow layer and its emission bands.