Publications
Analysis of mode coherence and intensity at megameter ranges
Abstract
The low-order modes constitute some of the most energetic arrivals at long ranges. Understanding fluctuations of these mode arrivals is crucial to their use as observables in matched field processing and tomography. Both simulated and experimental data indicate that at megameter ranges, the low modes have complex arrival patterns due to internal-wave-induced coupling. Analysis of broadband receptions at 3515 km from the ATOC experiment has shown that mode coherence times are on the order of 6 minutes and that centroid statistics provide useful measures of arrival time trends over the course of several months [Wage et al., IEEE Sensor Array and Multichannel Signal Processing Workshop Proceedings, pp. 102-106, March 2000]. The North Pacific Acoustic Laboratory (NPAL) experiment presents an opportunity for further research on broadband mode arrivals at megameter ranges. This study examines temporal coherence, intensity variations, and other mode statistics using data from the 40-element NPAL vertical line array. Experimental results are compared with PE simulations of propagation through internal waves of varying strengths, and the impact of the upslope propagation near the receivers on the mode statistics is discussed.
© 2001 Acoustical Society of America. This abstract may be downloaded for personal use only. Any other use requires the permission of the author and the Acoustical Society of America. The abstract appeared in the Journal of the Acoustical Society of America, vol. 109(5), p. 2385, May 2001 and may also be found on the JASA website.