Abstract
The study comprises a data set of CTD, optical properties—K 0(PAR), c p, a(PAR), b(PAR)—and optical constituents—Chl a, SPM, CDOM—from 72 shelf and off-shelf stations in the Faroe Islands (62°N, 7°W) North East Atlantic, in early spring 2005. Results showed that shelf waters surrounding the islands were cold and low saline, whereas off-shelf waters were warmer (~1°C) and more saline (~0.05) PSU. A pronounced oceanographic front separated the two waters, and diffuse light attenuation K 0(PAR), beam attenuation c p, Chl a, absorption a(PAR), and scattering coefficient b(PAR) were all significantly higher on the shelf. Analyses showed that off-shelf light attenuation K 0(PAR) was governed by Chl a, shown by a high (r 2 = 0.64) Chl a–K 0(PAR) correlation, whereas light attenuation on the shelf was governed by both Chl a, SPM, and CDOM in combination. A Chl a specific diffuse attenuation coefficient \( K_{0}^{*} \left( {\text{PAR}} \right) \) of 0.056 (m2 mg−1 Chl a) and a Chl a specific beam attenuation (\( c_{\text{p}}^{*} \)) of 0.27 (m2 mg−1 Chl a) coefficients were derived for the off-shelf. It is pointed out that Chl a is the single variable that changes over time as no rivers with high SPM and CDOM enter the shelf area. Data were obtained in early spring, and Chl a concentrations were low ~0.5 mg Chl a m−3. Spring bloom Chl a are about 10 mg Chl a m−3 and estimations showed that shelf K 0(PAR) will increase about 5 times and beam attenuation about 10 times. The Faroe Islands shelf–off-shelf waters is a clear example where physical conditions maintain some clear differences in optical properties and optical constituents. The complete data set is enclosed.
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Acknowledgments
The Faroe Fisheries Laboratory is greatly acknowledged by Lars Chresten Lund-Hansen for the opportunity to participate in the cruise. Fróðskaparsetur Føroya is acknowledged for financial support. Two anonymous reviewers are thanked for their comments and suggestions on the manuscript. Captain and crew onboard “Magnus Heinasson” are thanked for good cooperation and great kindness during the cruise. This research was partly funded by BP Amoco Exploration (Faroe Ltd.) and Anadarko Faroe Company.
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Lund-Hansen, L.C., Gaard, E. & Debes, H. Optical properties and optical constituents of the Faroe Islands shelf and off-shelf waters, North East Atlantic. Hydrobiologia 636, 285–293 (2009). https://doi.org/10.1007/s10750-009-9957-8
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DOI: https://doi.org/10.1007/s10750-009-9957-8