Flippin’ χSOLO, an Upper Ocean Autonomous Turbulence Profiling Float

Abstract

A new autonomous turbulence profiling float has been designed, built and tested in field trials off Oregon. Flippin’ χSOLO (FχS) employs a SOLO-II buoyancy engine that not only changes but also shifts ballast to move the center of mass to positions on either side of the center of buoyancy thus causing FχS to flip. FχS is outfitted with a full suite of turbulence sensors—two shear probes, two fast thermistors and pitot tube as well as a pressure sensor and 3-axis linear accelerometers. FχS descends and ascends with turbulence sensors leading, thereby permitting measurement through the sea surface. The turbulence sensors are housed antipodal from communication antennae so as to eliminate flow disturbance. By flipping at the sea surface, antennae are exposed for communications. The mission of FχS is to provide intensive profiling measurements of the upper ocean from 240m and through the sea surface, particularly during periods of extreme surface forcing. While surfaced, accelerometers provide estimates of wave height spectra and significant wave height. From day field trials, here we evaluate (i) the statistics from two FχS units and our established shipboard profiler, Chameleon, and (ii) FχS-based wave statistics by comparison to a nearby NOAA wave buoy.