title: Modal expansions for infrasound propagation and their implications for ground-to-ground propagation.
abstract: The use of expansions in vertical eigenmodes for long range infrasound propagation modeling in the effective sound speed approximation is investigated. The question of convergence of such expansions is related to the maximum elevation angles that are required. Including atmospheric attenuation leads to a non-self-adjoint vertical eigenvalue problem. The use of leading order perturbation theory for the modal attenuation is compared to the results of numerical solutions to the non-self-adjoint eigenvalue problem and conditions under which the perturbative result is expected to be valid are obtained. Modal expansions are obtained in the frequency domain; broadband signals must be modeled through Fourier reconstruction. Such broadband signal reconstruction is investigated and the relation between bandwidth, wavetrain duration, and frequency sampling is discussed.
authors.affiliation: National Center for Physical Acoustics, University of Mississippi, University, Mississippi 38677, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Waxler
authors.affiliation: Royal Netherlands Meteorological Institute, P.O. Box 201, 3730 AE, De Bilt, The Netherlands.
authors.forename: Jelle
authors.initials: J
authors.lastname: Assink
authors.affiliation: Leidos Corporation, 14668 Lee Road, Chantilly, Virginia 20151, USA.
authors.forename: Doru
authors.initials: D
authors.lastname: Velea