Spatial Interpolation of Two-Wavelengths Bio-Optical Models to Estimate the Concentration of Chlorophyll-a in A Tropical Aquatic System

  •  Igor Ogashawara    
  •  Enner de Alcântara    
  •  Petala Augusto-Silva    
  •  Claudio Barbosa    
  •  José Stech    


Bio-optical models have been used to estimate and map the concentration of chlorophyll-a (chl-a) in aquatic systems. Bio-optical models’ algorithms try to infer the concentration of optically active components in water from their inherent optical properties (IOPs). We proposed the use of two single wavelengths to retrieve chl-a concentration in a tropical aquatic system. The results were compared to in situ measurements of chl-a. To spatialized the results of the bio optical modeling, we tested the spatial interpolation following two methods: (1) ordinary kriging technique was used to spatialize the calculated values of estimated chl-a for each model; (2) ordinary kriging was used to spatialize the estimated Rrs from 470nm and 700nm then the two wavelengths models were calculated by a map algebra using the spatialized Rrs. We generated four different spatial interpolations of chl-a concentration. They were compared to the spatialized reference based on the in situ chl-a collected in the reservoir of Itumbiara–Goiás in the same period. The comparison was performed through the "Spatial Language for Algebraic Geoprocessing" (LEGAL) implemented at SPRING software. Results showed a better accuracy for the procedure using the spatialization of Rrs and map algebra of them. Thus the spatializaton of proximal remote sensing measurements in order to retrieve the optically active components in water should be performed through the interpolation of the Rrs.

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