|Title||Observations and transport theory analysis of low frequency, acoustic mode propagation in the Eastern North Pacific Ocean|
|Publication Type||Journal Article|
|Year of Publication||2013|
|Authors||Chandrayadula T.K, Colosi J.A, Worcester P.F, Dzieciuch M.A, Mercer J.A, Andrew R.K, Howe B.M|
|Journal||Journal of the Acoustical Society of America|
|Type of Article||Article|
|Keywords||amplitudes; intensity; internal waves; range; shallow-water; statistics; temporal coherence|
Second order mode statistics as a function of range and source depth are presented from the Long Range Ocean Acoustic Propagation EXperiment (LOAPEX). During LOAPEX, low frequency broadband signals were transmitted from a ship-suspended source to a mode-resolving vertical line array. Over a one-month period, the ship occupied seven stations from 50 km to 3200 km distance from the receiver. At each station broadband transmissions were performed at a near-axial depth of 800 m and an off-axial depth of 350 m. Center frequencies at these two depths were 75 Hz and 68 Hz, respectively. Estimates of observed mean mode energy, cross mode coherence, and temporal coherence are compared with predictions from modal transport theory, utilizing the Garrett-Munk internal wave spectrum. In estimating the acoustic observables, there were challenges including low signal to noise ratio, corrections for source motion, and small sample sizes. The experimental observations agree with theoretical predictions within experimental uncertainty. (C) 2013 Acoustical Society of America.