Prediction of the refractive index of seawater as a function of temperature,pressure, salinity and wavelength

An equation is given for predicting the absolute refractive index of seawater as a function of wavelength (in the visible region), temperature, pressure and salinity. This equation is based on the pure-water equation of H. Eisenberg, on the Tammann hypothesis and the Tait-Gibson equation of state for seawater. Comparison with experimental results (to 1380 bars) indicate an accuracy of ca. 0.0001 or better is achieved in the $\text{T-P}$ range of oceanographic interest.