Beam-wander analysis in turbulent ocean with the effect of the eddy diffusivity ratio and the outer scale

In this paper, we theoretically analyze the beam wander variance for the Gaussian beam propagation through weak oceanic turbulence. Particularly, we consider the effect of the eddy diffusivity ratio of salinity to temperature as well as the outer scale on the beam wander. To get to the tractable theoretical results, we first develop an approximate oceanic refractive-index spectrum with the outer scale and variable eddy diffusivity ratio. Based on this spectrum in weak turbulence, we then derive the closed-form expression for the beam wander variance. We present numerical results to show that the beam wander is either overestimated or underestimated as compared to the previous analyses which set the eddy diffusivity ratio to one. In addition, the finite outer scale of turbulence can significantly reduce the beam wander for Gaussian beams.