Estimating bowhead whale communications space using measured and modeled data.

In summer 2009, JASCO deployed ocean bottom hydrophones (OBHs) in the Chukchi Sea to measure natural and anthropogenic noise levels and monitor marine mammals acoustically. Acoustic data were collected from early August to mid October 2009. Ambient data were analyzed to compute noise levels for two sites: a relatively loud and relatively quiet one. Computer modeling was used to determine transmission losses at those sites. Manually acquired statistical data were used to determine average call length, and upper and lower frequencies for bowhead calls. Localization techniques were also used to determine source levels of the calls (Ref. Jonathan/Jeff paper). Using the above information and a modified version of the sonar equation, the space within which bowhead calls remain above ambient can be determined as an indication of maximum communication space. The noise conditions can be modified by simulating a ship passing through the area of an OBH and observing the change in communication space.