1 / 13

April 20, 2011

Ambient Noise in Admiralty Inlet. Chris Bassett, Brian Polagye , and Jim Thomson University of Washington Northwest National Marine Renewable Energy Center. NNMREC PI Update. April 20, 2011. Recording Hydrophone. Loggerhead DSG. Ambient Noise Sources. Average Conditions. Ship.

shada
Download Presentation

April 20, 2011

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ambient Noise in Admiralty Inlet • Chris Bassett, Brian Polagye, and Jim Thomson • University of Washington • Northwest National Marine Renewable Energy Center NNMREC PI Update April 20, 2011

  2. Recording Hydrophone Loggerhead DSG

  3. Ambient Noise Sources Average Conditions Ship Bedload Transport Quiet

  4. Ambient Noise Characteristics Hydrophone Deployments Cumulative Probability Density Temporal variability dominates over spatial variability

  5. Establishing Context for Observations Overnight Lull in Shipping Strong Currents First Run for Passenger Ferry Automatic Identification System Recording Hydrophone Doppler Profiler

  6. Vessel Traffic Monitoring with AIS • Automatic Identification System (AIS) transponders required on all vessels greater than 300 tonnes gross weight and passenger vessels • Continuous data collection and archiving

  7. Data Assimilation Vessel Proximity Noise Correlation SPL (dB re 1 μPa) Distance to closest vessel (km) Vessel noise drives broadband noise levels Source: Chris Bassett, forthcoming PhD dissertation

  8. Sound during High Currents Hydrophone Response Current Velocity

  9. Flow Shield Experiment Hydrophone with Flow Shield Unshielded Hydrophone High Velocity Region High Porosity Foam Hydrophone Element Doppler Velocimeter Sample volume aligned with hydrophone element Quiescent Region Hydrophone Pressure Case Source: Chris Bassett, forthcoming PhD dissertation

  10. Pseudo-Sound Identification Unshielded Hydrophone Hydrophone with Flow Shield Source: Chris Bassett, forthcoming PhD dissertation

  11. Propagating Sound during High Currents • Bedload transport • Elevated noise at 5-50 kHz • Consistent with size of gravel and shell hash observed during ROV surveys; O(1 cm) • Turbulent flow over rough surfaces • Potential contribution from advected turbulence • Cannot measure velocity fluctuations directly at frequencies of interest (e.g., > 300 Hz) (Hz) (Thorne, 1986) Source: Chris Bassett, forthcoming PhD dissertation

  12. Ambient Noise Summary • Ambient noise levels in Admiralty Inlet are high • Mean broadband SPL ≈ 119 dB re 1 μPa (20 Hz – 30 kHz) • Ambient noise exceeds NMFS marine mammal harassment threshold ≈50% of the time • Sound from shipping dominates ambient noise • Will complicate turbine noise measurements • Measurements during strong currents are challenging • Flow shields can significantly mitigate contamination by pseudo-sound • Bedload transport likely contributes to high current noise budget

  13. Thank You • This material is based upon work supported by the Department of Energy and Snohomish County PUD under Award Number DE-0002654 and the National Science Foundation Graduate Research Fellowship. Joe Talbert for keeping all equipment in working order. Sam Gooch, Joe Graber, and Alex DeKlerk for helping turn around instrumentation. Captain Andy Reay-Ellers for piloting skills during instrumentation deployment.

More Related