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| Format: | Dataset Open Access |
| Language: | en |
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PANGAEA
2018
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| Online Access: | https://doi.org/10.1594/PANGAEA.891476 |
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| _version_ | 1867170473184329728 |
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| author | van Haren, Hans |
| author_facet | van Haren, Hans |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | 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. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_891476 |
| institution | PANGAEA |
| language | en |
| publishDate | 2018 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | CTD and current meter data from SONNE cruises SO239 and SO240 van Haren, Hans CTD/Rosette; CTD3; CTD4; CTD5; CTD-RO; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; MOOR; Mooring; North Pacific Ocean; SO239; SO239_10-1; SO239_2-1; SO239_25-1; SO239_26-1; SO240; SO240_111-1; SO240_97-1; Sonne_2 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. |
| title | CTD and current meter data from SONNE cruises SO239 and SO240 |
| topic | CTD/Rosette; CTD3; CTD4; CTD5; CTD-RO; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; MOOR; Mooring; North Pacific Ocean; SO239; SO239_10-1; SO239_2-1; SO239_25-1; SO239_26-1; SO240; SO240_111-1; SO240_97-1; Sonne_2 |
| url | https://doi.org/10.1594/PANGAEA.891476 |