CTD and current meter data from SONNE cruises SO239 and SO240, supplement to: van Haren, Hans (2018): Abyssal plain hills and internal wave turbulence. Biogeosciences, 15(14), 4387-4403


A 400m long array with 201 high-resolution NIOZ temperature sensors was deployed above a north-east equatorial Pacific hilly abyssal plain for 2.5 months. The sensors sampled at a rate of 1Hz. The lowest sensor was at 7m above the bottom (ma.b.). The aim was to study internal waves and turbulent overturning away from large-scale ocean topography. Topography consisted of moderately elevated hills (a few hundred metres), providing a mean bottom slope of one-third of that found at the Mid-Atlantic Ridge (on 2km horizontal scales). In contrast with observations over large-scale topography like guyots, ridges and continental slopes, the present data showed a well-defined near-homogeneous "bottom boundary layer". However, its thickness varied strongly with time between  < 7 and 100ma.b. with a mean around 65ma.b. The average thickness exceeded tidal current bottom-frictional heights so that internal wave breaking dominated over bottom friction. Near-bottom fronts also varied in time (and thus space). Occasional coupling was observed between the interior internal wave breaking and the near-bottom overturning, with varying up- and down- phase propagation. In contrast with currents that were dominated by the semidiurnal tide, 200m shear was dominant at (sub-)inertial frequencies. The shear was so large that it provided a background of marginal stability for the straining high-frequency internal wave field in the interior. Daily averaged turbulence dissipation rate estimates were between 10−10 and 10−9m2s−3, increasing with depth, while eddy diffusivities were of the order of 10−4m2s−1. This most intense "near-bottom" internal-wave-induced turbulence will affect the resuspension of sediments.

DOI https://doi.org/10.1594/PANGAEA.891476
Related Identifier https://doi.org/10.5194/bg-15-4387-2018
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.891476
Creator van Haren, Hans
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 2018
Rights Data access is restricted (moratorium, sensitive data, license constraints)
OpenAccess false
Language English
Resource Type Supplementary Collection of Datasets
Format application/zip
Size 2 datasets
Discipline Earth System Research
Spatial Coverage (-117.015W, 11.840S, -116.945E, 11.861N); North Pacific Ocean
Temporal Coverage Begin 2015-03-10T06:00:00Z
Temporal Coverage End 2015-06-08T11:46:00Z