Shallow-water transmission measurements taken on the New Jersey Continental Shelf

Abstract

Calibrated acoustic transmission measurements were made under calm sea conditions on the New Jersey shelf near Amcor 6010, a surveyed area with known geophysical properties. The experiment was conducted in 73-m water with supporting measurements of salinity, temperature, and sound speed. These measurements were obtained with a vertical array of 24 equally spaced hydrophones at 2.5 m; one of which was on the bottom. A source towed at either 12- or 34-water depth transmitted one of two sets of four tones spaced between 50 and 600 Hz for each run to ranges of 4 and 26 km. The data were processed with Hankel transform and Doppler processing techniques to yield horizontal wave-number spectrum at several depths as well as mode shapes. Results were obtained along both a constant and a gradually depth varying radial. Similar modal interference patterns were observed at lower frequencies and critical angle bottom limited propagation at higher frequencies. The constant radial results were compared to calculations using several shallow-water propagation models employing both geoacoustic profiles derived from the geophysical parameters and Yamamoto's (1990) shear wave inversion. Predicted and measured levels generally agreed; however, differences in computed and measured modal interference patterns were observed. [Work sponsored by ONR 1125 OA and NUSC IR.]

An adaptive particle filtering approach to tracking modes in a varying shallow ocean environment

“…The seismic and coring data are combined with sediment properties measured at that site. Excellent agreement was determined between the model and data indicating a well-known, well-documented shallow water experiment with bottom interaction and yielding ideal data sets for investigating the applicability of a BP to measured ocean acoustic data [11], [12]. The experiment was performed at low frequencies (50-600Hz) in shallow water of 73m depth during a period of calm sea state.…”

“…This constitutes a soft statistical constraint of the parameter variations [16]. For our runs, we choose to start the processor with initial parameter estimates close to those values other researchers have meticulously estimated from the Hudson Canyon data set [11], [12].…”

“…In this section we discuss the development of the propagators for the Hudson Canyon experiment performed in 1988 in the Atlantic with the primary goal of investigating acoustic propagation (transmission and attenuation) using continuous wave data [11], [12]. The Hudson Canyon is located off the coast of New Jersey in the area of the Atlantic Margin Coring project borehole 6010 .…”

“…In this paper, we are primarily interested in investigating the application of the so-called "next generation" of model-based signal processing algorithms, primarily the unscented Kalman filter (UKF) and the particle filter (PF) with the goal of analyzing their performance on pressure-field data synthesized from the well-known Hudson Canyon experiments performed on the New Jersey shelf [11], [12]. Recall that the PF is a sequential Markov chain Monte Carlo (MCMC) Bayesian processor capable of providing reasonable performance for a multimodal problem estimating a non-parametric representation of the posterior distribution [24].…”

Analysis of modal evolution caused by a weakly range-dependent seabed in shallow water and its application to inversion for geoacoustic properties

“…In this section we will analyze a subset of experimental data measured in Hudson Canyon on the New Jersey continental shelf (Figure 6-8) by Carey and his co-workers [85,86]. In this experiment the field measurements were carried out with a vertical array of 24 equally spaced hydrophones as shown in Figure 6-9.…”