Oceanic spectrum of unstable stratification turbulence with outer scale and scintillation index of Gaussian-beam wave.

We develop a new spectrum of the refractive-index fluctuations for the unstable stratification ocean based on the linear combination of the temperature spectrum, salinity spectrum and coupling spectrum that all include the outer scale. Our oceanic spectrum agrees better with the experimental data than others do from low wave-number regions to high wave-number regions. Based on our proposed oceanic spectrum, we derive the analytical expression of the scintillation index of Gaussian-beam wave and investigate the influence of the light source and the channel parameters on the scintillation index of Gaussian-beam wave.