Finding Acoustically Stable Areas Through Empirical Orthogonal Function (EOF) Classification

Validity of sonar performance models is generally limited by environmental uncertainty, and particularly uncertainty in the sound-speed profile (SSP). Rapid environmental assessment (REA) missions, e.g., using gliders, and advanced ocean models may be used to reduce this uncertainty before sonar operation in hostile waters. This work shows how data from ocean models may be used for planning of REA missions. The area of operation is divided into oceanographically stable subareas using empirical orthogonal functions (EOFs) and different methods of clustering analyses on SSPs from the ocean model. The acoustic stability of each subarea is assessed using sonar performance modeling. Acoustically unstable areas are divided into smaller subareas. Acoustically stable groups are represented by a single SSP. A map of acoustically stable areas in the area of operation is the main output. Large, geographically contiguous groups indicate acoustically stable areas where frequent SSP measurements are unnecessary, e.g., low concentration of gliders. Small and noncontiguous groups indicate the opposite. Other applications include determination of suitable locations for sonar tests that require stable sonar conditions, and efficient optimization of sonar operation in acoustically stable areas.