Internal waves as a proposed mechanism for increasing ambient noise in an increasingly acidic ocean

Abstract

The effect on the ambient noise level in shallow water of the ocean growing more acidic is modeled. Because most noise sources are near the surface, high-order acoustic modes are preferentially excited. Linear internal waves, however, can scatter the noise into the low-order, low-loss modes most affected by the changes in acidity. The model uses transport theory to couple the modes and assumes an isotropic distribution for the noise sources. For a scenario typical of the East China Sea, the noise at 3 kHz is predicted to increase by 30%, about one decibel, as the pH decreases from 8.0 to 7.4.