Temperature and salinity correction coefficients for light absorption by water in the visible to infrared spectral region

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).