Low‐frequency sound absorption in the ocean

Recent work on low‐frequency sound absorption in the ocean and laboratory has been examined with regard to temperature dependence, pH dependence, and boron concentration in an effort to arrive at a practical expression consistent with existing knowledge for use in sonar prediction and design applications. It is found that the maximum absorption per wavelength, which is proportional to the chemical compressibility, is related to the pH at the sound channel axis depth. Furthermore, the relaxation frequency dependence on temperature as found by Simmons is examined in terms of the macroscopic viscosity of seawater, as suggested by Glotov for the magnesium sulphate relaxation at higher frequencies.