Remote ocean conditions experiment at Avalon

Photo courtesy of Catalina Marine Society Chief Scientist Craig Gelpi describes how the sensors are used to the divers.

Courtesy of Catalina Marine Society

Wave measurement data taken from Casino Point Dive Park

The Catalina Marine Society recently executed an experiment in the Casino Point Dive Park in development of a sea-state camera system to remotely and inexpensively measure sea conditions with commercially available cameras.

The goal of the project is to find a practical way to measure waves and use the information to protect diver and beachgoer safety.

On Sunday, May 22, Marine Society volunteers Ted Sharshan and Shawn Broes instrumented the Dive Park with wave detecting sensors while the western edge of the park was imaged with a camera by Karen Norris and Craig Gelpi from the hill above the Casino. CMS President Mike Doran coordinated activity from shore. The objective was to measure the exact wave conditions in the park with sensors on the sea bed and compare to subsequently deduce waves from the imagery obtained by the camera.

Wave measurement and recording can be a very costly. Typically, instrumented buoys that are moored to the seabed record their acceleration produced as the waves move past the buoy. These data are recorded and then telemetered to a base station. The accelerations are then integrated to determine wave heights. With additional sensors, wave propagation direction can also be computed. The whole process is very expensive, and impractical for many locations where knowledge of waves is required.

The Catalina Marine Society is a nonprofit organization dedicated to advance ocean knowledge in the local SoCal area mainly through the use of volunteers. The current project came out of discussions with the California Department of Parks and Recreation regarding the need for wave observations for beaches that are sometime dangerous for beachgoers and scuba divers, with the prime example being Monastery Beach at Monterey Bay (aka, “Mortuary Beach,” due to the number of wave-related deaths there). CMS also desires to measure wave characteristics along many coves along Santa Catalina Island to understand wave-induced water mixing.

Despite some hiccups in the sensor deployment, the May 22, experiment was deemed very successful and provides measurements that will be analyzed over the next year. These measurements include pressure at the seabed and current direction, in addition to the raw camera data. Results are expected to be presented at the next Ocean Optics conference in October.