Vessel noise in Puget Sound, WA
Bassett, C., B. Polagye, M. Holt, and J. Thomson, A vessel noise budget for Admiralty Inlet, Puget Sound, Washington (USA), J. Acoust. Soc. Am., 132(6), 3706-3719, 2012.
This figure shows the total number of vessel minutes recorded from May, 2010 to May, 2011 for different classes/types of vessels in 100m by 100m bins in Admiralty Inlet, Puget Sound, WA. These calculations are limited to vessels transmitting Automatic Identification System (AIS) signals. This figure visually shows that passenger vessels, cargo vessels, and tugs are common in the region and are important contributors to the ambient noise budget at the site.
One calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings to assess ambient noise in northern Admiralty Inlet, Puget Sound, WA (USA) and to quantify the contribution of vessel traffic. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site. Spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband (0.02–30 kHz) and marine mammal, or M-weighted, sound pressure levels showed variability driven largely by vessel traffic. Over the calendar year, 1363 unique AIS transmitting vessels were recorded, with at least one AIS transmitting vessel present in the study area 90% of the time. A vesselnoise budget was calculated for all vessels equipped with AIS transponders. Cargo ships were the largest contributor to the vesselnoise budget, followed by tugs and passenger vessels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessels resulted in a cumulative probability density function of broadband sound pressure levels that shows good agreement with 85% of the temporal data.