Modelling the Reflectance Spectrum of Different Phytoplankton Size Classes
Brewin, Bob; Sathyendranath, Shubha
Plymouth Marine Laboratory / NCEO, UNITED KINGDOM
We present a case-1 (open-ocean) bio-optical model whereby all inherent optical properties (IOPs) are tied to the chlorophyll biomass and dominant size class of phytoplankton (pico-, nano-or micro-phytoplankton). The model assumes each size class resides in a distinctive bio-optical environment. Chlorophyll-specific IOPs for each size class were derived from a global dataset of in-situ measurements. Sea-surface reflectances were simulated using the model. Distinct differences in the shape of reflectance spectrum were observed for each size class for a given chlorophyll concentration. Results have the potential to improve the estimation of phytoplankton size structure from past (e.g. MERIS) and present ocean-colour sensors (e.g. MODIS), and for developing new products for future missions (e.g. Sentinel-3 OLCI). The model also has applications in biogeochemical model validation and data assimilation.