Impact of small‐scale gravity waves on tracer transport

Abstract Small‐scale gravity waves, with horizontal wavelengths of up to a few hundred kilometers and vertical wavelengths of up to a few kilometers, play a crucial role in atmospheric tracer transport. However, their effects remain unresolved in climate models and must be parametrized. This study investigates how gravity waves influence large‐scale tracer distributions, utilizing a multiple‐scale analysis to systematically identify the governing terms of gravity wave‐induced tracer fluxes. The analysis reveals both leading‐order and next‐order impacts: the former being the inertia–gravity‐wave‐induced tracer Stokes drift, which acts perpendicular to both the large‐scale tracer gradient and the wave number, whereas the latter becomes significant at lower latitudes where Coriolis effects diminish. A numerical framework is developed to incorporate these fluxes into a gravity wave parametrization model, potentially enhancing climate model accuracy without requiring explicit resolution of small‐scale wave dynamics. Model validation against high‐resolution wave‐resolving simulations confirms the effectiveness of this approach. By improving the representation of gravity‐wave‐induced tracer transport, this research advances the accuracy of climate simulations, particularly in their depiction of microphysics and radiative processes.