Contents I. Introduction
Due to the turbulence effect, the refractive index of the transmission medium will change randomly, and the transmission of light waves and the imaging of the optical system are often greatly affected. Unlike the atmosphere, the refractive index fluctuation of seawater is affected by both temperature and salinity fluctuations. Until 2000, Only the analytical model of ocean turbulence power spectrum with bimodal structure proposed by Nikishov [1] can accurately describe the spatial and temporal fluctuations of the refractive index of seawater medium. However, the ocean turbulence power spectrum model established by Nikishov has certain drawbacks, that is, it is assumed that the seawater has stable stratification, and the low-density layer is always above the high-density layer. In fact, since surface water is affected by wind mixing and atmospheric heat exchange, seawater is usually not stably stratified, especially in mid-to-high latitudes, this density stratification will decrease or even disappear. Recently, Elamassie [2] established a spatial power spectrum model of refractive index fluctuations for isotropic and inhomogeneous seawater media, which takes into the instability of density stratification, eddy current thermal diffusivity and eddy current salt diffusion in practical underwater environments rate is not equal.
