Although satellite imagery cannot measure all aspects of the physical, chemical, and biological characteristics of lakes, it can efficiently measure several optically related constituents that are key indicators of water quality and ecological status: chlorophyll, phycocyanin (characteristic pigment of cyanobacteria), suspended solids, turbidity, colored dissolved organic matter (CDOM), and water clarity. Clarity, measured as Secchi depth (SD), is affected by all the previously listed indicators. These constituents absorb and/or scatter visible light at different wavelengths and thus affect the amount and spectral character of light reflected to satellite sensors. The reflected light measured
by sensors can be used to measure these constituents.
As the following link explains, the properties of light reflected from inland waters depend primarily on the relative abundance of three important “optical” constituents: plant pigments, CDOM, and turbidity (or suspended matter): Reflectance spectra related to dominant optical constituents. The links below provide background information and key findings from our measurements of water quality metrics by satellite imagery. Expand each term to see the different metrics of surface water quality at a glance, or click on their respective images to dive deeper.