Nonlinear Response of the Seismic Forcing on the atmospheric Boundary Layer: a 2D DNS Model

The evolution of phenomena at the interface between the terrestrial surface and the atmospheric boundary layer, like the coupling between litospheric and atmospheric phenomena during an earthquake, can be described as a nonlinear process, affected by mechanically induced disturbances originating from the solid Earth. In this work, a two-dimensional Direct Numerical Simulation (DNS) model is designed to investigate the nonlinear atmospheric response to seismic-wave-induced forcing within the lowest ~100 m of the atmosphere.
The model is based on the incompressible Navier–Stokes equations under the Boussinesq approximation. Stratification is imposed via a prescribed, constant, background buoyancy gradient representative of near-surface stable atmospheric conditions. Seismic forcing is introduced as a dynamical perturbation on the gravity acceleration field.
A set of numerical experiments has been performed to explore the nonlinear dynamics arising from the interaction between stratification, gravity forcing, and intrinsic flow instabilities. Simulations span a range of Reynolds numbers representative of the atmospheric boundary layer, enabling the investigation of transitions from linear wave dynamics to strongly nonlinear flow regimes. These first simulations demonstrate the feasibility of using a reduced-dimensional DNS framework to investigate atmosphere–solid Earth coupling processes at small scales. 
The results show the excitation and upward propagation of internal gravity waves, their nonlinear interaction with background shear, and the development of localized instabilities and turbulence. Energy diagnostics highlight anisotropic and scale-dependent transfers, as well as the conversion between kinetic and potential energy driven by the imposed seismic perturbation.
The model provides a controlled platform for studying nonlinear wave–boundary layer interactions and for assessing the potential role of seismic forcing in modulating near-surface atmospheric dynamics.
This study was carried out within the Space It Up project funded by the Italian Space Agency, ASI, and the Ministry of University and Research, MUR, under contract n. 2024-5-E.0 - CUP n. I53D24000060005.