Comparison of Turbulence Kinetic Energy Dissipation Rate Estimates from Two Ocean Microstructure Profilers

Abstract

Almost 1000 microstructure profiles from two separate groups on two separate ships using different instrumentation, signal processing, and calibration procedures were compared for a 3.5-day time period at 0°, 140°W and within 11 km of each other. Systematic bias in the estimates of ϵ is less than a factor of 2, which is within estimates of the cumulative uncertainties in the measurement of ϵ. Although there is no evidence for strong gradients in mean currents, water properties, or surface meteorology, occasional hourly averages of ϵ differ by several factors of 10. Both groups observed periods where ϵ estimates exceeded those of the other group by large factors. The authors believe that the primary reason for these large differences is natural variability, which appears to be greater in the meridional direction than in the zonal direction.