Spectral Dependence of the Seawater–Air Radiance Transmission Coefficient Journal of Atmospheric and Oceanic Technology

The transmission coefficient TL commonly used to propagate the upwelling nadir radiance from just below the ocean surface to above the surface has been assumed to be a constant value of 0.543 in seawater. Because the index of refraction of seawater varies with wavelength, salinity, and temperature, the variation of TL with these parameters should be taken into account, especially if low uncertainty is required for the quantities derived using TL. In particular, the wavelength dependence of this factor is important. For example, at a salinity of 35 g kg−1 and a temperature of 26°C, TL will be 1.3% lower at 380 nm and 1.1% higher at 700 nm than the constant value (0.543) and should be taken into account when calculating the water-leaving radiance and the normalized water-leaving radiance from in-water measurements. Grant no. NA15OAR4320064