Abstract
Temperature and shear microstructure data were collected by the epsilometer, a custom turbulence package, integrated onto a Teledyne-Webb APEX float. Profiles were conducted in both a controlled-ascent mode similar to the Argo mission (∼ 0.08 m s−1 rise rate) and at the float’s maximum rise rate of ∼ 0.3 m s−1, which might be used for shorter missions supporting process studies. In both modes, profiles of turbulent dissipation rate of kinetic energy ε and thermal dissipation rate χ were computed. Valid ε profiles were obtained in both profiling modes, though platform vibration was significant at the faster ascent rate, and probe sensitivity was reduced at the slower rise rate. Shear spectra resolve the viscous roll-off well, giving a noise floor for ε of about 3×10−10 W kg−1 in both modes. Individual temperature spectra also resolve the diffusive roll-off for χ about 2×10−11 K2 s−1 despite the presence of significant finescale structure in temperature, which impacted the quality of the temperature gradient spectra at low wavenumber. Following published best practices, each ε and χ estimate was kept or rejected based on a figure of merit measuring the goodness of fit of the measured spectrum to the theoretical form. ε cannot be computed when the buoyancy pump is active (3% of the time) due to excessive vibrations. At other times, about >65% and 75% of raw estimates of the turbulent dissipation rates ε and χ met our quality-control criteria, respectively.
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