Ocean Sci. Discuss., 10, 1833-1893, 2013
© Author(s) 2013. This work is distributed
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This discussion paper has been under review for the journal Ocean Science (OS). Please refer to the corresponding final paper in OS.
Experiments with the Secchi disk
E. Aas1, J. Høkedal2, and K. Sørensen3
1Department of Geosciences, University of Oslo, Gaustadalleen 21, 0349 Oslo, Norway
2Narvik University College, Lodve Langesgt. 2, 8508 Narvik, Norway
3Norwegian Institute for Water Research, Gaustadalleen 21, 0349 Oslo, Norway

Abstract. The Secchi depth and its relationships to other properties of the sea water in the Oslofjord–Skagerrak area have been investigated. White and black disks of different sizes have been applied, and the Secchi depth has been observed with the naked eye, through colour filters and with a water telescope. Spectral luminances and illuminances have been calculated from recordings of radiance and irradiance. A theoretical expression for the Secchi depth has been tested against field observations, and statistical relationships between Secchi depths and attenuation coefficients have been determined. Effects of size, colour filters, sun glitter and ship shadow have been quantified. The possibility to estimate quanta irradiance, chlorophyll a and total suspended material has also been studied.

Citation: Aas, E., Høkedal, J., and Sørensen, K.: Experiments with the Secchi disk, Ocean Sci. Discuss., 10, 1833-1893, doi:10.5194/osd-10-1833-2013, 2013.
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