Abstract: Apparatus is provided for optically measuring scalar irradiance or incident flux of radiant energy and for optically measuring naturally occurring chlorophyll fluorescence or upwelling radiance in a parcel of water in a natural setting. From a comparison of the two measurements, rate of primary photosynthetic production is calculated by appropriately programmed computer means. Readout means are provided to indicate the rate of primary production. Further, concentrations of chlorophyll that generate the primary production are also determined by means of the apparatus of this invention. The method of this invention, employing measurement instruments of the type disclosed, enables the determination of concentrations of chlorophyll and primary production in parcels of water.

Abstract: An apparatus for measuring scalar irradiance or the incident flux of radiant energy from a 4.pi. solid angle about a point. The present invention relates to an apparatus which comprises a solid spherical radiant energy collector, a radiant energy detector which converts radiant energy into electrical signal, a light conductor which transmits a portion of the radiant energy within the spherical collector to the detector, a means for conditioning the electrical signal such that the electrical signal responds to the intensity of the incident flux, and a means for displaying the conditioned signal. The apparatus further includes a spectral shaping assembly located intermediate the detector and the light conductor whereby the spectral characteristics of the radiant energy are adjusted to compensate for apparatus response in the desired spectral region.