On Doppler‐spreading models of internal waves

Present Doppler‐spreading models for short internal waves in the atmosphere and the ocean either neglect the time dependence of the background long‐wave shear entirely, or ignore time‐dependent effects in their parameterization of dissipation. We use ray and numerical simulations to examine the Doppler spreading of a short internal‐wave packet by an inertia‐wave packet. The results are enough to show that time dependence in the long‐wave shear can make a significant difference to short‐wave behavior, and will need to be taken into account in future modelling efforts.