Dynamics and Energetics of Fast Waves From the Earth's Surface to the Lower Thermosphere

Abstract We use a Full Wave Model to examine the dynamics and energetics of waves that can be excited in the troposphere by a large explosive event. We find resonant structures in phase speed wavenumber space that can have substructures with distinct properties. The primary waves found are Lamb waves and fast deep waves (denoted ) that have a hybrid internal‐external wave nature and were recently identified in observations. Lamb waves and thermospherically ducted waves are branches of two continuous forms separated by a gap in which Lamb waves are preempted by Lamb speed waves oscillating with the buoyancy frequency. We also find thermospherically ducted waves comprising a distinct form. Lamb and quasistatic waves are generically similar and are members of the same family. Lamb waves, exhibit energy partitioning in the mesosphere consisting almost entirely of elastic and horizontal kinetic energy. Quasistatic waves are nearly independent of horizontal wavenumber (nondispersive) while the non‐quasistatic waves exhibit rapid slowing with wavenumber. These and other non‐quasistatic waves are highly dispersive and should not constitute long‐lived wave packets. Only the quasistatic waves are associated with equivalent depths corresponding to a known global mode. Interference between the direct wave and the ground reflected wave produces a traveling deep amplitude minimum that can significantly reduce amplitudes near resonant waves. A deep minimum in surface pressure parallels the form and occurs where there is a state transition to one which has zero amplitude near the surface.