Abstract

The light absorption coefficient of water is dependent on temperature and concentration of ions, i.e. the salinity in seawater. Accurate knowledge of the water absorption coefficient, a, and/or its temperature and salinity correction coefficients, ΨT and ΨS, respectively, is essential for a wide range of optical applications. Values are available from published data only at specific narrow wavelength ranges or at single wavelengths in the visible and infrared regions. ΨT and ΨS were therefore spectrophotometrically measured throughout the visible, near, and short wavelength infrared spectral region (400 to ~2700 nm). Additionally, they were derived from more precise measurements with a point-source integrating-cavity absorption meter (PSICAM) for 400 to 700 nm. When combined with earlier measurements from the literature in the range of 2600 – 14000 nm (wavenumber: 3800 – 700 cm−1), the coefficients are provided for 400 to 14000 nm (wavenumber: 25000 to 700 cm−1).

© 2014 Optical Society of America

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References

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  1. R. Lemus, “Vibrational excitations in H2O in the framework of the local model,” J. Mol. Spectrosc. 225(1), 73–92 (2004).
    [Crossref]
  2. http://www1.lsbu.ac.uk
  3. D. Eisenberg and W. Kauzmann, The Structure and Properties of Water (Oxford University, 2005).
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  5. W. S. Pegau, D. Gray, and J. R. V. Zaneveld, “Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity,” Appl. Opt. 36(24), 6035–6046 (1997).
    [Crossref] [PubMed]
  6. J. M. Sullivan, M. S. Twardowski, J. R. V. Zaneveld, C. M. Moore, A. H. Barnard, P. L. Donaghay, and B. Rhoades, “Hyperspectral temperature and salt dependencies of absorption by water and heavy water in the 400-750 nm spectral range,” Appl. Opt. 45(21), 5294–5309 (2006).
    [Crossref] [PubMed]
  7. R. Röttgers and R. Doerffer, “Measurements of optical absorption by chromophoric dissolved organic matter using a point-source integrating-cavity absorption meter,” Limnol. Oceanogr. Methods 5, 126–135 (2007).
    [Crossref]
  8. X. Zhang and L. Hu, “Estimating scattering of pure water from density fluctuation of the refractive index,” Opt. Express 17(3), 1671–1678 (2009).
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    [Crossref] [PubMed]
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    [Crossref] [PubMed]
  12. J. R. Collins, “Change in the infrared absorption spectrum of water with temperature,” Phys. Rev. 26(6), 771–779 (1925).
    [Crossref]
  13. W. S. Pegau and J. R. V. Zaneveld, “Temperature-dependent absorption of water in the red and near-infrared portions of the spectrum,” Limnol. Oceanogr. 38(1), 188–192 (1993).
    [Crossref]
  14. L. Trabjerg and N. K. Højerslev, “Temperature influence on light absorption by fresh water and seawater in the visible and near-infrared spectrum,” Appl. Opt. 35(15), 2653–2658 (1996).
    [Crossref] [PubMed]
  15. H. Buiteveld, J. M. H. Hakvoort, and M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).
  16. V. S. Langford, A. J. McKinley, and T. I. Quickenden, “Temperature dependence of the visible-near-infrared absorption spectrum of liquid water,” J. Phys. Chem. A 105(39), 8916–8921 (2001).
    [Crossref]
  17. B. I. Lange, T. Brendel, and G. Hüttmann, “Temperature dependence of light absorption in water at holmium and thulium laser wavelengths,” Appl. Opt. 41(27), 5797–5803 (2002).
    [Crossref] [PubMed]
  18. L. Kou, D. Labrie, and P. Chylek, “Refractive indices of water and ice in the 0.65- to 2.5-µm spectral range,” Appl. Opt. 32(19), 3531–3540 (1993).
    [Crossref] [PubMed]
  19. P. Larouche, J. J. Max, and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. II. Factor analysis of the temperature effect on H2O and D2O,” J. Chem. Phys. 129(6), 064503 (2008).
    [Crossref] [PubMed]
  20. J. B. Cumming, “Temperature dependence of light absorption by water,” Nucl. Instrum. Methods Phys. Res. A 713, 1–4 (2013).
    [Crossref]
  21. J. J. Max and C. Chapados, “IR spectroscopy of aqueous alkali halide solutions: pure salt-solvated water spectra and hydration number,” J. Chem. Phys. 115(6), 2664–2675 (2001).
    [Crossref]
  22. J. J. Max and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. III. H2O and D2O spectra from 6000 to 0 cm-1.,” J. Chem. Phys. 131(18), 184505 (2009).
    [Crossref] [PubMed]
  23. R. M. Pope and E. S. Fry, “Absorption spectrum (380-700 nm) of pure water. II. Integrating cavity measurements,” Appl. Opt. 36(33), 8710–8723 (1997).
    [Crossref] [PubMed]
  24. D. M. Wieliczka, S. Weng, and M. R. Querry, “Wedge shaped cell for highly absorbent liquids: infrared optical constants of water,” Appl. Opt. 28(9), 1714–1719 (1989).
    [Crossref] [PubMed]
  25. R. Röttgers, C. Häse, and R. Doerffer, “Determination of the particulate absorption of microalgae using a point-source integrating-cavity absorption meter: verification with a photometric technique, improvements for pigment bleaching, and correction for chlorophyll fluorescence,” Limnol. Oceanogr. Methods 5, 1–12 (2007).
    [Crossref]
  26. J. Lyman and R. H. Fleming, “Composition of seawater,” J. Mar. Res. 3, 134–146 (1940).
  27. Y. Maréchal, “Infrared spectra of water. I. Effect of temperature and of H/D isotopic dilution,” J. Chem. Phys. 95(8), 5565 (1991).
    [Crossref]
  28. X. Quan and E. S. Fry, “Empirical equation for the index of refraction of seawater,” Appl. Opt. 34(18), 3477–3480 (1995).
    [Crossref] [PubMed]
  29. R. W. Austin and G. Halikas, “The index of refraction of seawater,” SIO Ref. No. 76–1, Scripps Inst. Oceanogr., La Jolla, 121 pp. (1976).
  30. D. J. Segelstein, “The complex refractive index of water,” Thesis (M.S.), Department of Physics, University of Missouri, Kansas City (1981).
  31. J. J. Max and C. Chapados, “Infrared transmission equations in a five media system: gas and liquid,” J. Math. Chem. 47(2), 590–625 (2010).
    [Crossref]
  32. M. Jonasz and G. Fournier, Light Scattering by Particles in Water: Theoretical and Experimental Foundations (Academic, 2007).

2013 (1)

J. B. Cumming, “Temperature dependence of light absorption by water,” Nucl. Instrum. Methods Phys. Res. A 713, 1–4 (2013).
[Crossref]

2010 (1)

J. J. Max and C. Chapados, “Infrared transmission equations in a five media system: gas and liquid,” J. Math. Chem. 47(2), 590–625 (2010).
[Crossref]

2009 (5)

2008 (1)

P. Larouche, J. J. Max, and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. II. Factor analysis of the temperature effect on H2O and D2O,” J. Chem. Phys. 129(6), 064503 (2008).
[Crossref] [PubMed]

2007 (2)

R. Röttgers, C. Häse, and R. Doerffer, “Determination of the particulate absorption of microalgae using a point-source integrating-cavity absorption meter: verification with a photometric technique, improvements for pigment bleaching, and correction for chlorophyll fluorescence,” Limnol. Oceanogr. Methods 5, 1–12 (2007).
[Crossref]

R. Röttgers and R. Doerffer, “Measurements of optical absorption by chromophoric dissolved organic matter using a point-source integrating-cavity absorption meter,” Limnol. Oceanogr. Methods 5, 126–135 (2007).
[Crossref]

2006 (1)

2004 (1)

R. Lemus, “Vibrational excitations in H2O in the framework of the local model,” J. Mol. Spectrosc. 225(1), 73–92 (2004).
[Crossref]

2002 (1)

2001 (2)

J. J. Max and C. Chapados, “IR spectroscopy of aqueous alkali halide solutions: pure salt-solvated water spectra and hydration number,” J. Chem. Phys. 115(6), 2664–2675 (2001).
[Crossref]

V. S. Langford, A. J. McKinley, and T. I. Quickenden, “Temperature dependence of the visible-near-infrared absorption spectrum of liquid water,” J. Phys. Chem. A 105(39), 8916–8921 (2001).
[Crossref]

1997 (2)

1996 (1)

1995 (1)

1994 (1)

H. Buiteveld, J. M. H. Hakvoort, and M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).

1993 (2)

W. S. Pegau and J. R. V. Zaneveld, “Temperature-dependent absorption of water in the red and near-infrared portions of the spectrum,” Limnol. Oceanogr. 38(1), 188–192 (1993).
[Crossref]

L. Kou, D. Labrie, and P. Chylek, “Refractive indices of water and ice in the 0.65- to 2.5-µm spectral range,” Appl. Opt. 32(19), 3531–3540 (1993).
[Crossref] [PubMed]

1991 (1)

Y. Maréchal, “Infrared spectra of water. I. Effect of temperature and of H/D isotopic dilution,” J. Chem. Phys. 95(8), 5565 (1991).
[Crossref]

1989 (1)

1940 (1)

J. Lyman and R. H. Fleming, “Composition of seawater,” J. Mar. Res. 3, 134–146 (1940).

1925 (1)

J. R. Collins, “Change in the infrared absorption spectrum of water with temperature,” Phys. Rev. 26(6), 771–779 (1925).
[Crossref]

Barnard, A. H.

Brendel, T.

Buiteveld, H.

H. Buiteveld, J. M. H. Hakvoort, and M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).

Chapados, C.

J. J. Max and C. Chapados, “Infrared transmission equations in a five media system: gas and liquid,” J. Math. Chem. 47(2), 590–625 (2010).
[Crossref]

J. J. Max and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. III. H2O and D2O spectra from 6000 to 0 cm-1.,” J. Chem. Phys. 131(18), 184505 (2009).
[Crossref] [PubMed]

P. Larouche, J. J. Max, and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. II. Factor analysis of the temperature effect on H2O and D2O,” J. Chem. Phys. 129(6), 064503 (2008).
[Crossref] [PubMed]

J. J. Max and C. Chapados, “IR spectroscopy of aqueous alkali halide solutions: pure salt-solvated water spectra and hydration number,” J. Chem. Phys. 115(6), 2664–2675 (2001).
[Crossref]

Chylek, P.

Collins, J. R.

J. R. Collins, “Change in the infrared absorption spectrum of water with temperature,” Phys. Rev. 26(6), 771–779 (1925).
[Crossref]

Cumming, J. B.

J. B. Cumming, “Temperature dependence of light absorption by water,” Nucl. Instrum. Methods Phys. Res. A 713, 1–4 (2013).
[Crossref]

Doerffer, R.

R. Röttgers and R. Doerffer, “Measurements of optical absorption by chromophoric dissolved organic matter using a point-source integrating-cavity absorption meter,” Limnol. Oceanogr. Methods 5, 126–135 (2007).
[Crossref]

R. Röttgers, C. Häse, and R. Doerffer, “Determination of the particulate absorption of microalgae using a point-source integrating-cavity absorption meter: verification with a photometric technique, improvements for pigment bleaching, and correction for chlorophyll fluorescence,” Limnol. Oceanogr. Methods 5, 1–12 (2007).
[Crossref]

Donaghay, P. L.

Donze, M.

H. Buiteveld, J. M. H. Hakvoort, and M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).

Fleming, R. H.

J. Lyman and R. H. Fleming, “Composition of seawater,” J. Mar. Res. 3, 134–146 (1940).

Fry, E. S.

Gray, D.

Hakvoort, J. M. H.

H. Buiteveld, J. M. H. Hakvoort, and M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).

Häse, C.

R. Röttgers, C. Häse, and R. Doerffer, “Determination of the particulate absorption of microalgae using a point-source integrating-cavity absorption meter: verification with a photometric technique, improvements for pigment bleaching, and correction for chlorophyll fluorescence,” Limnol. Oceanogr. Methods 5, 1–12 (2007).
[Crossref]

He, M.-X.

Højerslev, N. K.

Hu, L.

Hüttmann, G.

Kou, L.

Labrie, D.

Lange, B. I.

Langford, V. S.

V. S. Langford, A. J. McKinley, and T. I. Quickenden, “Temperature dependence of the visible-near-infrared absorption spectrum of liquid water,” J. Phys. Chem. A 105(39), 8916–8921 (2001).
[Crossref]

Larouche, P.

P. Larouche, J. J. Max, and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. II. Factor analysis of the temperature effect on H2O and D2O,” J. Chem. Phys. 129(6), 064503 (2008).
[Crossref] [PubMed]

Lemus, R.

R. Lemus, “Vibrational excitations in H2O in the framework of the local model,” J. Mol. Spectrosc. 225(1), 73–92 (2004).
[Crossref]

Lyman, J.

J. Lyman and R. H. Fleming, “Composition of seawater,” J. Mar. Res. 3, 134–146 (1940).

Maréchal, Y.

Y. Maréchal, “Infrared spectra of water. I. Effect of temperature and of H/D isotopic dilution,” J. Chem. Phys. 95(8), 5565 (1991).
[Crossref]

Max, J. J.

J. J. Max and C. Chapados, “Infrared transmission equations in a five media system: gas and liquid,” J. Math. Chem. 47(2), 590–625 (2010).
[Crossref]

J. J. Max and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. III. H2O and D2O spectra from 6000 to 0 cm-1.,” J. Chem. Phys. 131(18), 184505 (2009).
[Crossref] [PubMed]

P. Larouche, J. J. Max, and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. II. Factor analysis of the temperature effect on H2O and D2O,” J. Chem. Phys. 129(6), 064503 (2008).
[Crossref] [PubMed]

J. J. Max and C. Chapados, “IR spectroscopy of aqueous alkali halide solutions: pure salt-solvated water spectra and hydration number,” J. Chem. Phys. 115(6), 2664–2675 (2001).
[Crossref]

McKinley, A. J.

V. S. Langford, A. J. McKinley, and T. I. Quickenden, “Temperature dependence of the visible-near-infrared absorption spectrum of liquid water,” J. Phys. Chem. A 105(39), 8916–8921 (2001).
[Crossref]

Moore, C. M.

Pegau, W. S.

W. S. Pegau, D. Gray, and J. R. V. Zaneveld, “Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity,” Appl. Opt. 36(24), 6035–6046 (1997).
[Crossref] [PubMed]

W. S. Pegau and J. R. V. Zaneveld, “Temperature-dependent absorption of water in the red and near-infrared portions of the spectrum,” Limnol. Oceanogr. 38(1), 188–192 (1993).
[Crossref]

Pope, R. M.

Quan, X.

Querry, M. R.

Quickenden, T. I.

V. S. Langford, A. J. McKinley, and T. I. Quickenden, “Temperature dependence of the visible-near-infrared absorption spectrum of liquid water,” J. Phys. Chem. A 105(39), 8916–8921 (2001).
[Crossref]

Rhoades, B.

Röttgers, R.

R. Röttgers and R. Doerffer, “Measurements of optical absorption by chromophoric dissolved organic matter using a point-source integrating-cavity absorption meter,” Limnol. Oceanogr. Methods 5, 126–135 (2007).
[Crossref]

R. Röttgers, C. Häse, and R. Doerffer, “Determination of the particulate absorption of microalgae using a point-source integrating-cavity absorption meter: verification with a photometric technique, improvements for pigment bleaching, and correction for chlorophyll fluorescence,” Limnol. Oceanogr. Methods 5, 1–12 (2007).
[Crossref]

Sullivan, J. M.

Trabjerg, L.

Twardowski, M. S.

Weng, S.

Wieliczka, D. M.

Zaneveld, J. R. V.

Zhang, X.

Appl. Opt. (8)

W. S. Pegau, D. Gray, and J. R. V. Zaneveld, “Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity,” Appl. Opt. 36(24), 6035–6046 (1997).
[Crossref] [PubMed]

J. M. Sullivan, M. S. Twardowski, J. R. V. Zaneveld, C. M. Moore, A. H. Barnard, P. L. Donaghay, and B. Rhoades, “Hyperspectral temperature and salt dependencies of absorption by water and heavy water in the 400-750 nm spectral range,” Appl. Opt. 45(21), 5294–5309 (2006).
[Crossref] [PubMed]

L. Trabjerg and N. K. Højerslev, “Temperature influence on light absorption by fresh water and seawater in the visible and near-infrared spectrum,” Appl. Opt. 35(15), 2653–2658 (1996).
[Crossref] [PubMed]

B. I. Lange, T. Brendel, and G. Hüttmann, “Temperature dependence of light absorption in water at holmium and thulium laser wavelengths,” Appl. Opt. 41(27), 5797–5803 (2002).
[Crossref] [PubMed]

L. Kou, D. Labrie, and P. Chylek, “Refractive indices of water and ice in the 0.65- to 2.5-µm spectral range,” Appl. Opt. 32(19), 3531–3540 (1993).
[Crossref] [PubMed]

R. M. Pope and E. S. Fry, “Absorption spectrum (380-700 nm) of pure water. II. Integrating cavity measurements,” Appl. Opt. 36(33), 8710–8723 (1997).
[Crossref] [PubMed]

D. M. Wieliczka, S. Weng, and M. R. Querry, “Wedge shaped cell for highly absorbent liquids: infrared optical constants of water,” Appl. Opt. 28(9), 1714–1719 (1989).
[Crossref] [PubMed]

X. Quan and E. S. Fry, “Empirical equation for the index of refraction of seawater,” Appl. Opt. 34(18), 3477–3480 (1995).
[Crossref] [PubMed]

J. Chem. Phys. (4)

Y. Maréchal, “Infrared spectra of water. I. Effect of temperature and of H/D isotopic dilution,” J. Chem. Phys. 95(8), 5565 (1991).
[Crossref]

J. J. Max and C. Chapados, “IR spectroscopy of aqueous alkali halide solutions: pure salt-solvated water spectra and hydration number,” J. Chem. Phys. 115(6), 2664–2675 (2001).
[Crossref]

J. J. Max and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. III. H2O and D2O spectra from 6000 to 0 cm-1.,” J. Chem. Phys. 131(18), 184505 (2009).
[Crossref] [PubMed]

P. Larouche, J. J. Max, and C. Chapados, “Isotope effects in liquid water by infrared spectroscopy. II. Factor analysis of the temperature effect on H2O and D2O,” J. Chem. Phys. 129(6), 064503 (2008).
[Crossref] [PubMed]

J. Mar. Res. (1)

J. Lyman and R. H. Fleming, “Composition of seawater,” J. Mar. Res. 3, 134–146 (1940).

J. Math. Chem. (1)

J. J. Max and C. Chapados, “Infrared transmission equations in a five media system: gas and liquid,” J. Math. Chem. 47(2), 590–625 (2010).
[Crossref]

J. Mol. Spectrosc. (1)

R. Lemus, “Vibrational excitations in H2O in the framework of the local model,” J. Mol. Spectrosc. 225(1), 73–92 (2004).
[Crossref]

J. Phys. Chem. A (1)

V. S. Langford, A. J. McKinley, and T. I. Quickenden, “Temperature dependence of the visible-near-infrared absorption spectrum of liquid water,” J. Phys. Chem. A 105(39), 8916–8921 (2001).
[Crossref]

Limnol. Oceanogr. (1)

W. S. Pegau and J. R. V. Zaneveld, “Temperature-dependent absorption of water in the red and near-infrared portions of the spectrum,” Limnol. Oceanogr. 38(1), 188–192 (1993).
[Crossref]

Limnol. Oceanogr. Methods (2)

R. Röttgers and R. Doerffer, “Measurements of optical absorption by chromophoric dissolved organic matter using a point-source integrating-cavity absorption meter,” Limnol. Oceanogr. Methods 5, 126–135 (2007).
[Crossref]

R. Röttgers, C. Häse, and R. Doerffer, “Determination of the particulate absorption of microalgae using a point-source integrating-cavity absorption meter: verification with a photometric technique, improvements for pigment bleaching, and correction for chlorophyll fluorescence,” Limnol. Oceanogr. Methods 5, 1–12 (2007).
[Crossref]

Nucl. Instrum. Methods Phys. Res. A (1)

J. B. Cumming, “Temperature dependence of light absorption by water,” Nucl. Instrum. Methods Phys. Res. A 713, 1–4 (2013).
[Crossref]

Opt. Express (4)

Phys. Rev. (1)

J. R. Collins, “Change in the infrared absorption spectrum of water with temperature,” Phys. Rev. 26(6), 771–779 (1925).
[Crossref]

Proc. SPIE (1)

H. Buiteveld, J. M. H. Hakvoort, and M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).

Other (6)

http://www1.lsbu.ac.uk

D. Eisenberg and W. Kauzmann, The Structure and Properties of Water (Oxford University, 2005).

B. Woźniak and J. Dera, Light Absorption in Sea Water (Springer, 2007).

M. Jonasz and G. Fournier, Light Scattering by Particles in Water: Theoretical and Experimental Foundations (Academic, 2007).

R. W. Austin and G. Halikas, “The index of refraction of seawater,” SIO Ref. No. 76–1, Scripps Inst. Oceanogr., La Jolla, 121 pp. (1976).

D. J. Segelstein, “The complex refractive index of water,” Thesis (M.S.), Department of Physics, University of Missouri, Kansas City (1981).

Supplementary Material (2)

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Figures (8)

Fig. 1
Fig. 1

Temperature correction coefficient for pure water light absorption, ΨT, as a function of wavelength and wavenumber. To depict a complete spectrum, ΨT is shown relative to the pure water absorption coefficient, a [m−1], in (1/a)(da/dT)[% °C−1]. Note: 1) the water absorption coefficient values were combined from published data at 400 – 700 nm [23], 660 – 2500 nm [18], and 850 – 15000 nm [24]; 2) data of Buiteveld et al. 1994 [15] are offset corrected by −0.0135 m−1; 3) for Kou et al. 1993 [18]: ΨT was calculated from the difference in measurements of a for supercooled, liquid water at −8°C and liquid water at 22°C; 4) for Larouche et al. 2008 [19]: ΨT was calculated from the measurements of a for liquid water between 31°C and 61°C.

Fig. 2
Fig. 2

Salinity correction coefficient for pure water light absorption, ΨS, as a function of wavelength and wavenumber. To depict a complete spectrum, ΨS is shown relative to the pure water absorption coefficient, a [m−1], in (1/a)(da/dS) [% (g L−1)−1], where salinity is expressed as salt concentration in g L−1. Note: The water absorption coefficient values were taken from published data at 400 – 700 nm [23], 660 – 2500 nm [18], and 850 – 15000 nm [24]. The type of salt used to determine ΨS is indicated; ASW is artificial seawater. For Max and Chapados 2001 [21], ΨS was calculated from measurements of a for salt solutions of NaCl and MgCl2 with the concentration ratio of these salts in seawater as indicated. A dashed line indicates a −0.035% (g L−1) reduction of the water absorption coefficient due to a decrease in number of water molecules per volume.

Fig. 3
Fig. 3

Difference spectra of optical density (upper panels) and the corresponding difference in absorption coefficient (a) (lower panels) for pure water of 15° vs. 60°C. Measurements are performed with cuvettes of different path length as indicated in the legend and for different wavelength ranges with each cuvette (see Table 1).

Fig. 4
Fig. 4

Calculated temperature correction coefficient, ΨT, ( ± 2 S.D. vs. wavelength) for spectrophotometer measurements in a 100 mm cuvette, together with that obtained from PSICAM measurements.

Fig. 5
Fig. 5

Temperature correction coefficient for pure water, ΨT, in the spectral range of 400 - 2600 nm (Media 1). Given is the mean and 2xS.D. (n = 5 - 10). Note that in the lower panels the S.D. is smaller than the line thickness.

Fig. 6
Fig. 6

Difference spectra of optical density (upper panels) and the corresponding difference in absorption coefficient (a) (lower panels) for NaCl solutions compared to pure water. Measurements are performed with cuvettes of different path length as indicated in the legend and for different wavelength ranges with each cuvette (see Table 1).

Fig. 7
Fig. 7

Salinity correction coefficient, ΨS, (±2 S.D. vs. wavelength) calculated from measurements of a NaCl solution for spectrophotometer measurements in a 100 mm cuvette, together with that obtained from PSICAM measurements. Spectrophotometer results are offset-corrected at 420 nm; PSICAM results are not offset-corrected. Additionally shown in green is the spectrum of the PSICAM results corrected for a 0.015% g−1 L offset.

Fig. 8
Fig. 8

Salinity correction coefficient for pure water, ΨS, in the spectral range of 400 - 2660 nm (Media 2). Given is the mean and 2xS.D. (n = 5 - 10) for artificial seawater (ASW). Additionally shown is the spectrum for NaCl without S.D. for clarity.

Tables (1)

Tables Icon

Table 1 Spectral measurement ranges for cuvettes of different path length.

Metrics