Modal group time spreads in weakly range-dependent deep ocean environments

Ilya A. Udovydchenkov, Michael G. Brown

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The temporal spread of modal group arrivals in weakly range-dependent deep ocean environments is considered. It is assumed that the range dependence is sufficiently weak that mode coupling is predominantly local in mode number. The phrase "modal group arrival" is taken here to mean the contribution to a transient wave field corresponding to a fixed mode number. There are three contributions to modal group time spreads which combine approximately in quadrature. These are the reciprocal bandwidth (the minimal pulse width), a deterministic dispersive contribution that is proportional to bandwidth and grows like range r, and a scattering-induced contribution that grows approximately like r32. The latter two contributions are shown to be proportional to the waveguide invariant Β, a property of the background sound speed profile. The results presented, based mostly on asymptotic theory, are shown to agree well with full-wave numerical wave field simulations and available exact mode theoretical results. Simulations are shown that correspond approximately to conditions during the LOAPEX acoustic propagation experiment.

Original languageEnglish (US)
Pages (from-to)41-50
Number of pages10
JournalJournal of the Acoustical Society of America
Issue number1
StatePublished - 2008

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Acoustics and Ultrasonics


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