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Title: Spectroradiometric monitoring for open outdoor culturing of algae and cyanobacteria

We assess the measurement of hyperspectral reflectance for the outdoor monitoring of green algae and cyanobacteria cultures with a multi-channel, fiber-coupled spectroradiometer. Reflectance data acquired over a four-week period are interpreted via numerical inversion of a reflectance model, in which the above-water reflectance is expressed as a quadratic function of the single backscattering albedo, dependent on the absorption and backscatter coefficients. The absorption coefficient is treated as the sum of component spectra consisting of the cultured species (green algae or cyanobacteria), dissolved organic matter, and water (including the temperature dependence of the water absorption spectrum). The backscatter coefficient is approximated as the scaled Hilbert transform of the culture absorption spectrum with a wavelength-independent vertical offset. Additional terms in the reflectance model account for the pigment fluorescence features and the water surface reflection of sunlight and skylight. For both the green algae and cyanobacteria, the wavelength-independent vertical offset of the backscatter coefficient is found to scale linearly with daily dry weight measurements, providing the capability for a non-sampling measurement of biomass in outdoor ponds. Other fitting parameters in the reflectance model are compared to auxiliary measurements and physics-based calculations. The magnitudes of the sunlight and skylight water-surface contributions derived from themore » reflectance model compare favorably with Fresnel reflectance calculations, while the reflectance-derived quantum efficiency of Chl-a fluorescence is found to be in agreement with literature values. To conlclude, the water temperature derived from the reflectance model exhibits excellent agreement with thermocouple measurements during the morning hours and highlights significantly elevated temperatures in the afternoon hours.« less
 [1] ;  [2] ;  [3] ;  [3] ;  [2]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States). Remote Sensing and Energetic Materials Department
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Bioenergy and Defense Technology Department
  3. Sapphire Energy, San Diego, CA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0003-6935; APOPAI; 505076
Grant/Contract Number:
AC04-94AL85000; BM0102060-05794-1004173
Accepted Manuscript
Journal Name:
Applied Optics
Additional Journal Information:
Journal Volume: 53; Journal Issue: 24; Related Information: Proposed for publication in Applied Optics.; Journal ID: ISSN 0003-6935
Optical Society of America (OSA)
Research Org:
Sandia National Laboratories Albuquerque, NM; Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States