Description - Diffuse attenuation coefficient (Kd) is a
descriptor of the underwater light fields that varies with depth, solar
altitude and time. It is an indicator of the penetrative component of
solar radiation. Kd490 is Kd measured at 490 nm.
Description - Photosynthetically Active Radiation (PAR) is the quantum energy flux from the sun in the
spectral range 400-700 nm. The algorithms estimates daily (i.e. 24
hour average) PAR reaching the ocean surface.