On the synergistic use of SAR and optical imagery to monitor cyanobacteria blooms: the Curonian Lagoon case study

Multi-sensor satellite data are used to assess cyanobacteria blooms in the Curonian Lagoon. The exploitation of SAR, in combination with optical data, is investigated to take full advantage from the all-weather, night/day SAR imaging capability. A dataset of images has been analyzed to: 1) study the effect of cyanobacteria on microwave signals; 2) assess the daily evolution of cyanobacteria bloom from multi-sensors data; and 3) evaluate the dependence of dynamics of blooms on winds. The results show a significant correlation (R2 > 0.8, p<0.001) between the X- and C-band Normalized Radar Cross Section (NRCS) attenuation and the NIR-Red band ratio Index, with the latter considered as a proxy for the presence of cyanobacteria blooms. A combined use of microwave and optical observations can improve the detection of cyanobacteria blooms and their dependency on wind action.