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Proceedings Paper

Instrument to measure in situ visible light absorption in natural waters
Author(s): J. H. M. Hakvoort; A. E. R. Beeker; J. Krijgsman
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Paper Abstract

A submersible absorption meter was built to measure the light absorption plus backscattering coefficients of natural waters in one term. The radiance attenuation is measured close to the surface of a Lambertian light source and it is measured along the direction of the net vector irradiance. Photons scattered out of this normal direction are replaced by photons initially travelling at a deviating direction being scattered into the normal direction. Photons scattered in the backward direction are lost. The performance of the absorption meter was tested in the laboratory working with several simple test suspensions and in the field in estuarine and in marine water. Radiance attenuation spectra of clear water and absorption spectra of clear water matched closely. The radiance attenuation of algae increased linearly with concentration of chlorophyll (alpha) in the measured range of 0 - 70 mg m-3, while the radiance attenuation spectrum was very close to the absorption spectrum of the algal sample as measured with a semi-integrating sphere. An offset between these spectra remained. This was not observed when field data from estuarine and marine water were compared to laboratory measurements.

Paper Details

Date Published: 26 October 1994
PDF: 12 pages
Proc. SPIE 2258, Ocean Optics XII, (26 October 1994); doi: 10.1117/12.190123
Show Author Affiliations
J. H. M. Hakvoort, Delft Univ. of Technology (Netherlands)
A. E. R. Beeker, Delft Univ. of Technology (Netherlands)
J. Krijgsman, Delft Univ. of Technology (Netherlands)

Published in SPIE Proceedings Vol. 2258:
Ocean Optics XII
Jules S. Jaffe, Editor(s)

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