"Climate and Forecast (CF)" . . . . . "downwelling photosynthetic photon spherical irradiance in sea water" . "Downwelling radiation is radiation from above. It does not mean \"net downward\". \"Photosynthetic\" radiation is the part of the spectrum which is used in photosynthesis e.g. 300-700 nm. The range of wavelengths could be specified precisely by the bounds of a coordinate of radiation_wavelength. Photon spherical irradiance is the photon flux incident on unit area of a hemispherical (or \"2-pi\") collector. A photon flux is specified in terms of numbers of photons expressed in moles." .