title: A test of deep water Rytov theory at 284 Hz and 107 km in the Philippine Sea.
abstract: Predictions of log-amplitude variance are compared against sample log-amplitude variances reported by White, Andrew, Mercer, Worcester, Dzieciuch, and Colosi [J. Acoust. Soc. Am. 134, 3347-3358 (2013)] for measurements acquired during the 2009 Philippine Sea experiment and associated Monte Carlo computations. The predictions here utilize the theory of Munk and Zachariasen [J. Acoust. Soc. Am. 59, 818-838 (1976)]. The scattering mechanism is the Garrett-Munk internal wave spectrum scaled by metrics based on measured environmental profiles. The transmitter was at 1000 m depth and the receivers at nominal range 107 km and depths 600-1600 m. The signal was a broadband m-sequence centered at 284 Hz. Four classes of propagation paths are examined: the first class has a single upper turning point at about 60 m depth; the second and third classes each have two upper turning points at roughly 250 m; the fourth class has three upper turning points at about 450 m. Log-amplitude variance for all paths is predicted to be 0.04-0.09, well within the regime of validity of either Born or Rytov scattering. The predictions are roughly consistent with the measured and Monte Carlo log-amplitude variances, although biased slightly low. Paths turning in the extreme upper ocean (near the mixed layer) seem to incorporate additional scattering mechanisms not included in the original theory.
authors.affiliation: Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA.
authors.forename: Rex K
authors.initials: RK
authors.lastname: Andrew
authors.affiliation: Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: White
authors.affiliation: Applied Physics Laboratory, University of Washington, Seattle, Washington 98105, USA.
authors.forename: James A
authors.initials: JA
authors.lastname: Mercer
authors.affiliation: Scripps Institution of Oceanography, La Jolla, California 92037, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Dzieciuch
authors.affiliation: Scripps Institution of Oceanography, La Jolla, California 92037, USA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Worcester
authors.affiliation: Naval Postgraduate School, Monterey, California 93943, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Colosi