Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/os-2017-103
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
30 Jan 2018
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Ocean Science (OS).
Acoustic mapping of mixed layer depth
Christian Stranne1,2, Larry Mayer3, Martin Jakobsson1,2, Elizabeth Weidner3, Kevin Jerram3, Thomas C. Weber3, Leif G. Anderson4, Johan Nilsson2,5, Göran Björk4, and Katarina Gårdfeldt6 1Department of Geological Sciences, Stockholm University, Stockholm, Sweden
2Bolin Center for Climate Research, Stockholm University, Stockholm, Sweden
3Center for Coastal and Ocean Mapping, University of New Hampshire, Durham, New Hampshire, USA
4Department of Marine Sciences, University of Gothenburg, Gothenburg, 40530, Sweden
5Department of Meteorology, Stockholm University, Stockholm, Sweden
6Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, Sweden
Abstract. The ocean surface mixed layer is a nearly universal feature of the world oceans. The depth of the mixed layer (MLD) influences the exchange of heat and gases between the atmosphere and the ocean and constitutes one of the major factors controlling ocean primary production as it affects the vertical distribution of biological and chemical components in near-surface waters. Direct observations of the MLD are traditionally made by means of conductivity, temperature and depth (CTD) casts. However, CTD instrument deployment limits the observation of temporal and spatial variability of the MLD. Here, we present an alternative method where acoustic mapping of the MLD is done remotely by means of commercially available ship-mounted echosounders. The method is shown to be highly accurate when the MLD is well defined and biological scattering does not dominate the acoustic returns. These prerequisites are often met in the open ocean and it is shown that the method is successful in 95 % of data collected in the central Arctic Ocean. The primary advantages of acoustically mapping the MLD over CTD measurements are: (1) considerably higher temporal and horizontal resolutions and (2) potentially larger spatial coverage.
Citation: Stranne, C., Mayer, L., Jakobsson, M., Weidner, E., Jerram, K., Weber, T. C., Anderson, L. G., Nilsson, J., Björk, G., and Gårdfeldt, K.: Acoustic mapping of mixed layer depth, Ocean Sci. Discuss., https://doi.org/10.5194/os-2017-103, in review, 2018.
Christian Stranne et al.
Christian Stranne et al.
Christian Stranne et al.

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