Accession Number : AD0637874

Title :   GUIDED INFRASONIC MODES IN A TEMPERATURE- AND WIND-STRATIFIED ATMOSPHERE.

Corporate Author : AVCO CORP WILMINGTON MASS SPACE SYSTEMS DIV

Personal Author(s) : Pierce,Allan D.

Report Date : 01 SEP 1966

Pagination or Media Count : 44

Abstract : The propagation of infrasonic waves in a realistic model atmosphere which includes a variable wind profile as well as a variable temperature profile is discussed quantitatively for wave periods between 1 and 10 minutes. The numerical method used for the computation of phase and group velocity curves and other characteristic quantities associated with the possible guided modes is an extension of the multilayer method used previously by Press and Harkrider and by Pfeffer and Zarichny for atmospheres without winds. The effects of winds on the propagation are assessed by examining computations carried out for various fixed directions of the horizontal group velocity and from the computation of deviations of the phase velocity direction from group velocity direction for the case of propagation crosswind. Pressure-height profiles of various frequencies propagating in various modes are exhibited and excitation amplitudes for ground level sources (excluding the frequency spectrum of the source) are plotted versus frequency for various modes and various group velocity directions. Qualitative explanations of the computed results are given and the implications of the results to actual waveforms are discussed. (Author)

Descriptors :   (*ACOUSTICS, ATMOSPHERES), VERY LOW FREQUENCY, MECHANICAL WAVES, PROPAGATION, WIND, ATMOSPHERIC TEMPERATURE, ATMOSPHERE MODELS

Subject Categories : Atmospheric Physics
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE