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The SeaSoar, manufactured by Chelsea Instruments, Ltd., is a towed vehicle equipped with impeller-forced wings that can be rotated to allow the vehicle to undulate in the upper ocean. The wings are controlled through the multi-conductor tow cable by sending current signals generated by a PC-based controller onboard ship to a hydraulic unit inside the vehicle. Typical instrumentation includes a SeaBird 911+ CTD with pressure and dual conductivity and temperature sensors, and optical instrumentation such as fluorometer, transmissometer, PAR sensor, an experimental bioluminescence sensor and others.

Under the original open-ocean configuration, SeaSoar undulates between the surface and about 400 meters depth while being towed on faired cable at about eight knots. A typical dive cycle takes about 12 minutes to complete, providing an up- and down profile every 3 km. We obtained more frequent sampling during our shallow water experiments (PRIMER, GLOBEC), where a complete dive cycle down to 100 meters takes on average three minutes, providing a horizontal resolution of about 400 meters at mid-depth.

(Woods Hole Oceanographic Institution)