RED BAND DIFFERENCE. The Red Band Difference (RBD) algorithm is used as a proxy of relative chlorophyll-a fluorescence and is calculated as the difference between two red bands. As described by Amin et al. (2009) and tested in Irish waters by Jordan et al. (2021), the RBD algorithm is less sensitive to coloured dissolved organic matter, suspended particulate matter and atmospheric corrections, which makes it useful in both open and coastal waters. Colours indicate relative fluorescence, with warmer colours representing higher fluorescence indicative of higher bloom concentration. Gray colour represents clouds and other invalid data and black indicates ‘no detection’ of bloom, or could represent multiple cloudy days in the area. The images were derived from Copernicus Sentinel-3A & B satellite data from the European Organisation for the Exploitation of Meteorological Satellites and daily imagery are processed by NOAA, National Centers for Coastal Ocean Science. Please follow this link for a chlorophyll-a product.
Amin R, Zhou J, Gilerson A, Gross B, Moshary F, and Ahmed S (2009). Novel optical techniques for detecting and classifying toxic dinoflagellate Karenia brevis blooms using satellite imagery. Opt. Express 17, 9126–9144. doi: 10.1364/oe.17.009126
Jordan C, Cusack C, Tomlinson MC, Meredith A, McGeady R, Salas R, et al. (2021). Using the red band difference algorithm to detect and monitor a Karenia spp. bloom off the south coast of Ireland, June 2019. Front. Mar. Sci. 8:638889. doi: 10.3389/fmars.2021.638889
