Modeling the vertical directionality of wind-generated noise in deep ocean using Pekeris-branch-cut-based normal modes

Vertical directionality is an important property of wind-generated noise. In this paper, we extend the vertical directionality model of wind-generated noise in [12] from shallow water to deep ocean. In order to treat the overhead and distant noise simultaneously, we propose to use Pekeris-branch-cut-based normal modes to represent the Green's functions from noise sources to receivers. Comparing with the situation in shallow water, we find that the diagonal dominance of the noise modal covariance is weaker in deep ocean. In our model, both diagonal elements and a plenty of off-diagonal elements near the main diagonal line are involved into the modeling progress to ensure the accuracy. The errors could be introduced by neglecting the off-diagonal elements are simulated and analyzed. Using wave propagation theory, we give a reasonable explanation of why the diagonal dominance of the noise modal covariance matrix is weaker in deep ocean.