Suitability of MODIS 250 m resolution band data for quantitative mapping of cyanobacterial blooms

Abstract

Optical properties of three bloom-forming cyanobacteria - Aphanizomenon flos-aquae var. baltica, Anabaena circinalis, and Nodularia spumigena - were studied in laboratory experiments. Specific absorption and backscattering coefficients of these cyanobacteria were used in an optical model to simulate water reflectance in the case of different concentrations of cyanobacteria. MODIS band 1 (620-670 nm) response to changes in the concentration of cyanobacteria was simulated from the spectral reflectance data. The results show that MODIS band 1 response to changes in the concentration of cyanobacteria is nonlinear. Band 1 response is strongest in the case of N. spumigena, indicating that quantitative mapping of this species in bloom conditions is easier than in the case of the other two species of cyanobacteria investigated.