Group Velocities of Atmospheric Gravity Waves

Atmospheric gravity waves generated by low-altitude nuclear explosions have been detected by ground-level microbarographs and by ionospheric instruments. Group velocity dispersion curves have been computed for propagation over the short and long great-circle paths. Apparent lower velocities over the short paths are interpreted as due to the “rise time” of the nuclear disturbances to ionospheric levels with subsequent generation of gravity waves at those levels. Corrections to the travel times to account for the “rise time” delays are estimated to be ∼13 min or more. Corrected group velocity dispersion curves are found to agree with theoretical group velocity dispersion for atmospheric surface waves.