Microstructure observations during the spring 2011 STRATIPHYT-II cruise in the northeast Atlantic
Small-scale temperature and conductivity variations have been measured in the upper 100 m of the northeast Atlantic during the STRATIPHYT-II cruise (Las Palmas–Reykjavik, 6 April–3 May 2011). The measurements were done at midday and comprised 2 to 15 vertical profiles at each station. The derive...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2012-11-01
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| Series: | Ocean Science |
| Online Access: | http://www.ocean-sci.net/8/945/2012/os-8-945-2012.pdf |
| Summary: | Small-scale temperature and conductivity variations have been measured in the upper 100 m of the northeast Atlantic during the STRATIPHYT-II cruise (Las Palmas–Reykjavik, 6 April–3 May 2011). The measurements were done at midday and comprised 2 to 15 vertical profiles at each station. The derived turbulent quantities show a transition between weakly-stratified (mixed layer depth, MLD, <100) and well-mixed waters (MLD > 100), which was centered at about 48° N. The temperature eddy diffusivities, <I>K<sub>T</sub></I>, range from 10<sup>&minus;5</sup> to 10<sup>0</sup> m<sup>2</sup> s<sup>−1</sup> in the weakly-stratified stations, and range from 3 &times; 10<sup>&minus;4</sup> to 2 &times; 10<sup>0</sup> m<sup>2</sup> s<sup>−1</sup> in the well-mixed stations. The turbulent kinetic energy dissipation rates, ε, range from 3 &times; 10<sup>&minus;8</sup> to 2 &times; 10<sup>&minus;6</sup> m<sup>2</sup> s<sup>−3</sup> south of the transition zone, and from 10<sup>&minus;7</sup> to 10<sup>&minus;5</sup> m<sup>2</sup> s<sup>−3</sup> north of the transition zone. The station-averaged <I>K<sub>T</sub></I> values throughout the mixed layer increase exponentially with the wind speed. The station-averaged ε values throughout the mixed layer scale with the wind stress similarity variable with a scaling factor of about 1.8 in the wind-dominated stations (&epsilon; &approx; 1.8 <I>u</I><sub>&star;</sub><sup>3</sup>/(&minus;&kappa;<I>z</I>)). The values of <I>K<sub>T</sub></I> and ε are on average 10 times higher compared to the values measured at the same stations in July 2009. The results presented here constitute a unique data set giving large spatial coverage of upper ocean spring turbulence quantities. |
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| ISSN: | 1812-0784 1812-0792 |