Comparison of hybrid three-dimensional modeling with measurements on the continental shelfa)
Measured 415 Hz received beam level vs source-receiver range for CALOPS 2007 run 1 north. The signal goes on and off every minute indicating an in-plane path at 10° and an inshore-refracted bath at ranges greater than 46 km. Unfortunately an interferer lides over the refracted path from 30–45 km source range.
(Color online) (upper panel) Measured received levels at 206 Hz for true bearing (dark stars) and refracted bearing (light dots). (Lower panel) Measured arrival angle of true (dark) and refracted bearing (light).
(Color online) (Clockwise from upper left) Bathymetry, acoustic normal mode 3, 6, and 10 phase speed at 206 Hz. Contours are drawn at 0 and 30 m water depth. The strong correlation between the bathymetry and the phase speeds is clear, as is the greater increase in phase speed with shoaling for the higher modes. Latitude is plotted on the x-axis in anticipation of model runs with range being north-south and depth being east-west.
(Color online) Adiabatic mode parabolic equation computation for modes 1, 3, 6, 10, at 206 Hz. The shadow zone, upper caustic and multiple horizontal arrival regions are clear for each mode. The shadow zone and refracted energy increases with mode number.
(Color online) (Upper) Adiabatic mode—ray fan computed for 206 Hz mode 9. Refracted rays are plotted in black, reflected in white. (Lower) Coherent sum of mode amplitudes for 100 m source at 206 Hz. Note the affect of the bathymetry to rotate the wavefronts, leading to a complex interference structure.
(Color online) 206 Hz mode 9 plane wave beam projections vs lat/lon with source ship track. (Upper left) −30°. (Upper right) −20°. (Lower left) 8°, the true bearing and (lower right) 8° and −20°. The line is the source track.
Coherent mode sum AMPE at 206 Hz CBF response vs source range with measured arrival angles (dots) overlaid. The AMPE accurately predicts the behavior of presence and angle of arrival of the direct and in-shore refracted paths.
(Color online) (Left panels) 250 Hz transmission loss model-data comparison and inversion cost functions for run 1 N (upper) and run 3 N (lower).
Mode 9—10oarrival angle from source to receiver. (Top) eigenray vs position overlaid on the mode 9 phase speed (middle) PE acoustic field with cylindrical spreading removed, (bottom) mode decomposition of PE field vs range with cylindrical spreading removed.
Mode 9—25oarrival angle from source to receiver. (Top) eigenray vs position overlaid on the mode 9 phase speed (middle) PE acoustic field with cylindrical spreading removed, (bottom) mode decomposition of PE field vs range with cylindrical spreading removed.
Geo-acoustic inversion (from Appendix A) result used for modeling.
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