Preprints
https://doi.org/10.5194/os-2021-107
https://doi.org/10.5194/os-2021-107

  08 Nov 2021

08 Nov 2021

Review status: this preprint is currently under review for the journal OS.

Technical note: Turbulence measurements from a Light Autonomous Underwater Vehicle

Eivind Hugaas Kolås1, Tore Mo-Bjørkelund2, and Ilker Fer1 Eivind Hugaas Kolås et al.
  • 1Geophysical Institute, University of Bergen and Bjerknes Center for Climate Research, Bergen, Norway
  • 2Norwegian University of Science and Technology, Trondheim, Norway

Abstract. A self-contained turbulence instrument from Rockland Scientific was installed on a Light Autonomous Underwater Vehicle (AUV) from OceanScan Marine Systems and Technology Lda. We report on the data quality and discuss limitations of dissipation estimated from two shear probes during a deployment in the Barents Sea in February 2021. The AUV mission lasted for 5 hours, operating at a typical horizontal speed of 1.2 m s−1. The AUV was programmed to find and cross the maximum along-path thermal gradient at 10, 20 and 30 m depths along 4 km transects. Although the AUV vibrations contaminate the shear probe records, the noise is mitigated by removing vibration-induced components from shear spectra using accelerometer signal measured in multiple directions. Dissipation rate estimates in the observed transects varied in the range 1 × 10−8 and 6 × 10−6 W kg−1, with the values from the two orthogonal probes typically in agreement to within a factor of 2. Dissipation estimates from the AUV show good agreement with nearby vertical microstructure profiles obtained from the ship during the transects, indicating that the turbulence measurements from the AUV are reliable for this relatively turbulent environment. However, the lowest reliable dissipation rates are limited to 5 × 10−8 W kg−1, making this setup unfit for use in quiescent environments.

Eivind Hugaas Kolås et al.

Status: open (until 03 Jan 2022)

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Eivind Hugaas Kolås et al.

Data sets

Dissipation measurements from AUV transects across a surface temperature front in the Barents Sea Ilker Fer; Tore Mo-Bjørklund; Eivind Kolås https://doi.org/10.21335/NMDC-1821443450

Eivind Hugaas Kolås et al.

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Short summary
A turbulence instrument was installed on a Light Autonomous Underwater Vehicle (AUV) and deployed in the Barents Sea in February 2021. We present the data quality and discuss limitations when measuring turbulence from the AUV. AUV vibrations contaminate the turbulence measurements, yet the measurements were sufficiently cleaned when the AUV operated in turbulent environments. In quiescent environments the noise from the AUV became relatively large, making the turbulence measurements unreliable.