Three-Dimensional Propagation of Tsunami-Generated Internal Waves in the Atmosphere

Abstract:

Tsunami-generated acoustic-gravity waves propagate in the atmosphere up to the ionosphere, where they have been observed to have an impact on the Total Electron Content (TEC). We extend Broutman et al. (2014) to three dimensions by simulating the propagation of linearized internal waves in the atmosphere with horizontal background winds. Our goal is to investigate how the vertical variation of the angle between the background wind and the boundary forcing affects the previous two-dimensional results and in particular how much energy reaches the lower ionosphere. We examine propagation through an idealized wind jet at a fixed angle to the tsunami direction of propagation, through a wind spiral, and through a realistic atmospheric profile corresponding to the 2004 Sumatra Tsunami.

In the first case, wave propagation follows a similar pattern to that of the two-dimensional problem, although the transmission and reflection coefficients are affected by the horizontal wavenumber in the y-direction. In the second case, the wind spiral affects the number and the height of turning points greatly and the overall propagation is quite different. The realistic tsunami case is more complex and differs substantially from the two-dimensional results.