Using ICON to model from ground to thermosphere - a global perspective

We present a new global, high-resolution (10 km) simulation of the atmosphere using the ICON modeling framework and extending the vertical domain from the surface to the mid-thermosphere up to 250 km. With this configuration, gravity waves (GWs) are explicitly resolved up to a horizontal wavelength of about 50 km, and we can study the generation and dissipation across atmospheric layers, providing an opportunity to investigate GW propagation into the mesosphere and lower thermosphere (MLT) and their interactions with large-scale tides. Particular emphasis is put on cascading gravity waves, whereby primary waves generate secondary and higher-order GWs, and on their role in coupling the lower and upper atmosphere.

The simulation captures the interaction of gravity waves and tides with dynamically active regions, including the polar vortex leading to a sudden stratospheric warming (SSW). Achieving global, whole-atmosphere simulations at this resolution poses significant numerical challenges, including maintaining a consistent energy budget and ensuring the stability of the forward-in-time integrator across a wide range of scales and densities. We discuss strategies employed to address these challenges and assess their implications for model fidelity.

This modeling capability represents a critical step toward realistic whole-atmosphere prediction and provides an essential tool for the design and interpretation of coordinated satellite observation campaigns targeting GW–tide interactions and vertical coupling processes.