Ocean Ultrasonic Shear and Compression Viscosities

ABSTRACT

A comprehensive description of ocean molecular flow and deformation is provided with the help of hydrodynamic and ultrasonic principles. Hydrodynamic computation of true or natural viscosities shows that ocean shear viscosity (ηG), compression viscosity (ηK), and extensional viscosity (ηE) are interrelated. There are no experimental methods available for the in situ measurement of these viscosities. Sound absorption coefficients (α obs) allow to know the ultrasonic shear (ηUG), compression (ηUK), and longitudinal (ηL) viscosities, which decrease with increasing frequency and increase with increasing temperature, the flow activation energies having nearly equivalent values; pressure (depth) increase/decrease them at low/high frequencies. The viscosities η*UG, η*UK, η*L are approached at about 1000 KHz. They decrease with temperature and pressure, and increase with salinity. The η*UG becomes equal to the true shear viscosity η G at the viscosity ratio δ = ηUK / ηUG = 0.