Optical Limnology—a Manifesto

Abstract

Since the optical properties of the aquatic medium control the penetration of solar radiation in natural waters, a knowledge of these properties is essential for an understanding of the functioning of aquatic ecosystems. The inherent optical properties of the water need to be determined: the absorption coefficients for the soluble and particulate fractions at a series of wavelengths over the visible-photosynthetic spectral range, and the scattering coefficient (or turbidity, which is proportional to scattering). The apparent optical properties of the water should also be measured; the vertical attenuation coefficient for downward irradiance in the whole photosynthetic waveband (and if possible at specific wavelengths as well), the irradiance reflectance, and the visual transparency. Methods for measuring the values of these properties in inland waters are discussed.