Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
Ocean Sci., 14, 403-415, 2018
https://doi.org/10.5194/os-14-403-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
06 Jun 2018
High-resolution diapycnal mixing map of the Alboran Sea thermocline from seismic reflection images
Jhon F. Mojica1,2, Valentí Sallarès2, and Berta Biescas2,3 1Center for global Sea Level Change CSLC – NYUAD, Abu Dhabi, United Arab Emirates
2Institute of Marine Sciences, ICM-CSIC, Barcelona, Spain
3Consiglio Nazionale delle Ricerche CNR-ISMAR, Bologna, Italy
Abstract. The Alboran Sea is a dynamically active region where the salty and warm Mediterranean water first encounters the incoming milder and cooler Atlantic water. The interaction between these two water masses originates a set of sub-mesoscale structures and a complex sequence of processes that entail mixing close to the thermocline. Here we present a high-resolution map of the diapycnal diffusivity around the thermocline depth obtained using acoustic data recorded with a high-resolution multichannel seismic system. The map reveals a patchy thermocline, with spots of strong diapycnal mixing juxtaposed with areas of weaker mixing. The patch size is of a few kilometers in the horizontal scale and of 10–15 m in the vertical one. The comparison of the obtained maps with the original acoustic images shows that mixing tends to concentrate in areas where internal waves, which are ubiquitous in the surveyed area, become unstable and shear instabilities develop, enhancing energy transfer towards the turbulent regime. These results are also compared with others obtained using more conventional oceanographic probes. The values estimated based on the seismic data are within the ranges of values obtained from oceanographic data analysis, and they are also consistent with reference theoretical values. Overall, our results demonstrate that high-resolution seismic systems allow the remote quantification of mixing at the thermocline depth with unprecedented resolution.
Citation: Mojica, J. F., Sallarès, V., and Biescas, B.: High-resolution diapycnal mixing map of the Alboran Sea thermocline from seismic reflection images, Ocean Sci., 14, 403-415, https://doi.org/10.5194/os-14-403-2018, 2018.
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Short summary
The Alboran Sea is a dynamically active region. The interaction between Mediterranean and Atlantic water originates a set of sub-mesoscale structures and a complex sequence of processes that entail mixing close to the thermocline. Here we present a high-resolution map of the diapycnal diffusivity around the thermocline depth obtained using acoustic data recorded with a high-resolution multichannel seismic system. The map revels a patchy thermocline, with areas of strong diapycnal mixing.
The Alboran Sea is a dynamically active region. The interaction between Mediterranean and...
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