Numerical study of the spatial and temporal variability of ambient noise in the coastal region east of Taiwan Strait

Noise soundscape represents the characteristics and spatial distributions of the ambient noise level under various noise source mechanisms. This is a significant index while describing an underwater acoustic environment, especially in the subjects related to marine mammal protection. Under the effects of topography, sediment, and oceanographic features, underwater soundscape varies with time and space. This paper focuses on estimating mean soundscape of wind driven noise and shipping noise and their spatial and temporal variability in the coastal region east of Taiwan Strait, which is the main habitat of the Sousa Chinensis. The ambient noise is studied numerically and local wind field and shipping density observed by Automatic identification Systems (AIS) are applied to generate noise source field. As for the ocean environment, the time varying/spatial dependent temperature profiles generated by the Taiwan Coastal Ocean Nowcast/Forecast System (TCONFS), which formulated on the basis of the Princeton Ocean Model, is used for water column variability, and both topography database and geo-acoustic database are used to describe the bottom. The modeling results demonstrate the temporal/spatial variability induced by ocean environment, manifested by measured data. [This work was supported by National Science Council of Taiwan and Bureau of Energy (Grant No.102-D0105).]