Why the Southern California Operating Area? The Northeastern portion of the operating area offers: Shallow Water, Steep Bathymetry, Underwater Ridges, and the Instrumented Underwater Range California Duplicates anticipated deployment environments. Southern California provides ships the ability to conduct complicated/Integrated ASW training in conditions that are similar to many of those Strike Groups would expect to see on deployment: shallow water, steep bathymetry, and underwater ridges. No other area is available to U.S. forces that offers the combination of air warfare (Fallon, China Lake), a shallow water undersea warfare range (San Clemente Island (SCI)), instrumented undersea warfare ranges (SCI), bombing ranges (SCI, Pendleton, El Centro), radars (various), air targets (Point Mugu), surface and underwater targets and support (SCI, others), amphibious landing areas (Camp Pendleton, SCI), training support, and emergency divert fields such as those that have been developed or are readily available in the SOCAL area. Instrumented range allows accurate reconstruction of events (ground truth) allowing in-depth evaluation of performance against measures of effectiveness. Also allows real-world ability to validate/verify current and advanced tactics, techniques and procedures.

Why the Southern California Operating Area? Provides Strike Groups the ability to conduct complicated/Integrated SONAR training in the environmental conditions that are similar to those where they would expect to fight. Duplicates anticipated deployment environments. Southern California provides ships the ability to conduct complicated/Integrated ASW training in conditions that are similar to many of those Strike Groups would expect to see on deployment: shallow water, steep bathymetry, and underwater ridges. No other area is available to U.S. forces that offers the combination of air warfare (Fallon, China Lake), a shallow water undersea warfare range (San Clemente Island (SCI)), instrumented undersea warfare ranges (SCI), bombing ranges (SCI, Pendleton, El Centro), radars (various), air targets (Point Mugu), surface and underwater targets and support (SCI, others), amphibious landing areas (Camp Pendleton, SCI), training support, and emergency divert fields such as those that have been developed or are readily available in the SOCAL area. Instrumented range allows accurate reconstruction of events (ground truth) allowing in-depth evaluation of performance against measures of effectiveness. Also allows real-world ability to validate/verify current and advanced tactics, techniques and procedures.

Navy Active SONAR Mitigation Efforts Nominal source level of 235dB (measured 1 meter from transmitter) Marine Mammals emit up to 228dB SONAR Operation w/o Powerdown 189dB 181dB 179dB 0dB 200 meters 175dB 500 meters 175dB 171dB 1,000 meters 175dB 169dB Reduced SONAR Operation As whales get closer, crew reduces SONAR output Temporary Threshold Shift (TTS) ~ 195dB (est) Non-injurious Can produce behavioral effects Evaluated on Bottlenose Dolphins and Beluga Whales in San Diego Harbor. Essentially a captive sample and may not corrolate to open ocean. 215 dB for permanent psychological effects is based on extrapolating the 195 dB data. Ambient noise of 40dB IAW NWP 76-1: Spherical Spreading (1-1000 yds): Spreading Loss = 20 Log (R2/R1) 200 yds – 189 dB 200 meters – 188 dB 500 yds – 181 dB 500 meters – 180 dB 1000 yds – 175 dB 1000 meters – 174 dB Cylindrical Spreading (>1000 yds): Spreading Loss = 10 Log (R2/R1)