New England shelf break acoustic experiment (NESBA): Assimilation of acoustic pressure observations

Abstract

The NESBA Signals and Noise experiment was conducted in April–May 2021. The goal of the experiment is to assess the potential for sonar prediction effectiveness gains given improved environmental awareness. This talk addresses the NESBA sub-goal of demonstrating that acoustic pressure observations could be assimilated into high-resolution ocean models (i.e., Regional NCOM) resulting in lower analysis and forecast errors for both the ocean environment variables and acoustic predictions. The steps involved in this experimental analysis include: (1) measurement of broadband signals received by drifting vertical arrays; (2) generation of empirical orthogonal function (EOF) representations of the local sound speed environment based on NOAA Regional NCOM forecasts; (3) use of acoustic simulation to generate simulated signals for general elements of the EOF state space; and (4) the use of optimization techniques to determine the EOF coefficients that best match each set of acoustic measurements. Multiple optimizations are to be conducted, each resulting in a synthetic CTD measurement at a specific location and time. These synthetic CTDs will be assimilated into Regional NCOM and comparisons will be made between baseline NCOM forecasts, NCOM forecasts including the synthetic CTD data, and CTD measurement data. [Work supported by the Office of Naval Research.]