Spatial power spectrum of natural water turbulence with any average temperature, salinity concentration, and light wavelength

Abstract

The power spectrum of water optical turbulence is shown to vary with its average temperature ⟨ T ⟩ and average salinity concentration ⟨ S ⟩ , as well as with light wavelength λ . This study explores such variations for ⟨ T ⟩ ∈ [ 0 ∘ C , 30 ∘ C ] , ⟨ S ⟩ ∈ [ 0 p p t , 40 p p t ] covering most of the possible natural water conditions within the Earth’s boundary layer and for visible electromagnetic spectrum, λ ∈ [ 400 n m , 700 n m ] . For illustration of the effects of these parameters on propagating light, we apply the developed power spectrum model for estimation of the scintillation index of a plane wave (the Rytov variance) and the threshold between weak and strong turbulence regimes.

Phase discontinuities induced scintillation enhancement: coherent vortex beams propagating through weak oceanic turbulence

“…where v is the momentum diffusivity and ε is the energy dissipation rate. The dimensionless parameters c i (i ∈ {T, S, TS}) are [25] c…”

“…In Eq. ( 8) χ i (i ∈ {T, S, TS}) are the ensembleaveraged variance dissipation that can be defined by [25] χ…”

“…The eddy diffusivity ratio d r is derived from density ratio R ρ = α |H|/β. And it can be written as [25]…”

Oceanic non-Kolmogorov optical turbulence and spherical wave propagation

“…The OTOPS model of [2] and its derivatives [16,17] were all based on the first of the four models (called below H1) for a single-scalar turbulent advection developed by Hill [18]. An alternative model for the Kolmogorov oceanic optical turbulence has been recently obtained in [19][20][21][22] by numerically fitting model 4 of the Hill's paper (called below H4) [18]. The H4-based models are more precise than the H1-based models in high spatial frequency region, and, hence, have advantages in oceanic cases with the wide-ranged Prandtl/Schmidt numbers [21,23].…”

“…On considering the results of these oceanic turbulence measurements and the practical need for light propagation predictions made in various oceanic turbulence regimes, we set the aim for this paper to develop an OTOPS that extends the model suggested in [21,22] to non-Kolmogorov regime. This requires (I) developing the non-Kolmogorov temperature/salinity spectrum which is applicable for the marine environment with the wide-ranged Prandtl/Schmidt numbers, and (II) deriving the temperature-salinity co-spectrum which can not be directly obtained by analogy with a single-scalar spectrum, since the power law exponents of the two advected scalars can be generally different.…”