LAUSR

We compare estimates of the turbulent dissipation rate, ε, obtained independently from coincident measurements of shear and temperature microstructure in the southeastern Beaufort Sea, a strongly stratified, low-energy environment. The measurements were collected over 10 days in 2015 by an ocean glider equipped with microstructure instrumentation; they yield 28,575 shear-derived and 21,577 temperature-derived ε estimates. We find agreement within a factor of 2 from the two types of estimates when ε exceeds 3 × 10−11 W/kg, a threshold we identify as the noise floor of the shear-derived estimates. However, the temperature-derived estimates suggest that the dissipation rate is lower than this threshold in 58% of our observations. Further, the noise floor of the shear measurements artificially skews the statistical distribution of ε below 10−10 W/kg, that is, in 70% of our observations. The shear measurements overestimate portions of the geometric mean vertical profile of ε by more than an order of magnitude and underestimate the overall variability of ε by at least 2 orders of magnitude. We further discuss uncertainties that arise in both temperatureand shear-derived ε estimates in strongly stratified, weakly turbulent conditions, and we demonstrate how turbulence spectra are systematically modified by stratification under these conditions. Using evidence from the temperature-gradient spectral shapes and from the observed ε distributions, we suggest that the temperature-derived dissipation rates are reliable to values as small as 2 × 10−12 W/kg, making them preferable for characterizing the turbulent dissipation rates in the weakly turbulent environment of this study.