| Popis: |
The presentation reviews the environmental modeling conducted in support of a submarine acoustic target strength trial. The measurements at 20‐40 kHz were collected at a shallow site in North West Atlantic. The site bottom was gravel; surface winds were 2‐6 m/s. For ranges less than 1.8 km, the CW reverberation at 24, 28, and 39 kHz agreed with CASS‐GRAB predictions; beyond 1.8 km, the model output underestimated the measurements. The predictions were computed for APL‐UW surface and bottom models appropriate for trial conditions: negligible surface reflection loss and scattering strength, low bottom reflection loss and high bottom scattering strength. The LFM reverberation at 21, 28, and 36 kHz for 2 kHz bandwidth signals matched the CW reverberation after compensation for the pulse range resolution and frequency differences in the beam responses and volume attenuation. Agreement among CASS‐GRAB prediction and data verified the assumed sonar and environmental parameters used in propagation loss modeling and increased confidence in the target strength estimates. The latter were consistent with previously reported values. |
