Research Ambient Noise DIrectionality (RANDI) 3.1 Physics Description.

Abstract : A description is presented of the physics behind the Research Ambient Noise Directionality (RANDI) model version 3.1. The RANDI 3.1 model can be used to predict ambient acoustical noise levels and directionalities at low to midfrequencies for shallow and deep water environments. Ambient noise due to shipping, wind, flow noise, and system noise are considered. Shipping noise can be calculated for highly variable environments and is done using either a finite element or split step parabolic equation. Local wind noise is computed based on the range independent theory of Kuperman Ingenito, including both discrete (normal modes) and continuous spectra. Navy Standard and historical data bases are used to describe the environment. Sample outputs are presented to illustrate products of the model.