Influence of source structure and background wind on the excitation, propagation, and structure of Lamb and Pekeris waves

Abstract The excitation, propagation, and structure of eruption-induced Lamb and Pekeris waves, as well as the influence of background winds on them, are investigated using a linear hydrostatic atmospheric model. The amplitudes of the excited waves and the time required to transition to the theoretical structures predicted by classical tidal theory vary substantially depending on the horizontal extent and altitude of the initial temperature perturbation representing the eruption. Numerical experiments also demonstrate that the phase speed, node altitude, and damping characteristics of the Pekeris wave can deviate significantly from their theoretical counterparts in the presence of background winds; the underlying physical mechanisms responsible for these modifications are also examined. Furthermore, satellite-based visualization of the Lamb and Pekeris waves excited by the eruption of the Hunga Tonga-Hunga Ha’apai volcano reveals a clear difference in the damping characteristics between the eastward- and westward-propagating Pekeris waves, which is consistent with the results of our numerical calculations. These wind effects on the Pekeris wave are also consistent with recent simulation results using a high-top general circulation model.