Spotter Platform delivers highly accurate measurements of subsurface currents in field comparison with ADCP

At Sofar, we reduce the cost and complexity of collecting ocean data at scale. Our flexible Spotter Platform helps ocean scientists, engineers, and other marine professionals easily gather and transmit data at and below the surface. These real-time ocean insights accelerate research, power sustainable commercial solutions, and save time and money.

Spotter makes it easier and more affordable to gather ocean data without compromising on hardware durability or data accuracy. To test Spotter’s robustness and precision, we commissioned a field study comparing its subsurface current measurement capability to that of an Acoustic Doppler Current Profiler (ADCP), widely viewed as the industry standard for subsurface current measurement.

The field comparison found that Spotter’s observations of current speed and direction were nearly identical to those made by the ADCP [access the full study here]. Anecdotally, Spotter was easier to deploy and recover than the ADCP, and the data it collected was significantly easier to access. These results validate Spotter as a more cost-effective, accessible, and deployable alternative to an ADCP.

Key parameters and results of field study comparing Spotter and ADCP

The field study was conducted by Integral Consulting, Inc. (Integral) off the coast of Santa Barbara, California, in the Pacific Ocean. Integral deployed:

• A Spotter Platform with a Spotter buoy, Smart Mooring, and integrated Aanderaa 4830 ZPulse® Doppler Current Sensor
• A Teledyne RDI Sentinel Workhorse ADCP

The Spotter and ADCP collected data concurrently for 24 days prior to recovery. Integral’s analysis of the subsurface current data collected by each platform found that:

• Observations of current speed and direction were nearly identical. Figure A below shows the strong agreement between Spotter and the ADCP’s measurements during the 24-day deployment.

• A regression model (Figure B) identified a strong linear curve fit (R² = .904) for measurements of current speed.

• Overall, the observations made by Spotter closely aligned with the observations made by the ADCP with low bias and low root-mean-square difference.

How the Spotter Platform combines ease of use with data accuracy and accessibility

While Spotter and the ADCP recorded nearly identical observations of current speed and direction during the study, any similarity between the devices ended there. On multiple fronts, Spotter proved to be a more accessible and flexible solution than the ADCP during the field study:

• All data collected by Spotter was transmitted via cellular — with satellite fallback available — and was remotely accessible via the Spotter Dashboard for the duration of the study. The current observations made by the ADCP were not accessible until the device was recovered from the ocean, delaying the start of data analysis.
• The ADCP lost power unexpectedly on May 15th. Without remote data access, there was no way to know that the ADCP was dead and required new batteries. Spotter reliably runs on a combination solar-battery power system and its power status is viewable at all times on the Spotter Dashboard.
• The device recovery process was conducted by a dive team from the University of California, Santa Barbara. The dive team was only necessary because of the cumbersome nature of the ADCP; when deployed on the seafloor with a bottom mounted frame and batteries, an ADCP can easily weigh over a hundred pounds. Dive teams are expensive, require careful coordination, and are not available to all marine professionals. Recovery and deployment of Spotter, conversely, is a straightforward process that can be conducted from a small boat with limited personnel. Spotter weighs less than 20 pounds and is about the size of a basketball.
• Spotter’s total cost of ownership — including purchase, deployment, recovery, maintenance, data access, etc. — is significantly lower than that of the ADCP.

Collecting current data — or any data — in the ocean is historically an expensive and difficult process. Sofar’s Spotter Platform is helping change that, empowering marine professionals to make surface and subsurface observations of waves, temperature, water level, and more, with less cost and complexity.

Access the full field study here. To learn more about the Spotter Platform, please contact our Sales team.