Diurnal cycle of phytoplankton carbon and chlorophyll during the 36-hour experiment in the Adriatic Sea.

The COSIMO cruise was conducted during spring 2015 into the Adriatic Sea. For 36 hours, the ship was halted at an open sea location. During this experiment, vertical profiles of CTD data, chlorophyll concentration, radiometric and IOP observations (also overnight), were collected. Following published models, the phytoplankton carbon is estimated as C = SF ( bbp(443) – bbpNAP(443)), where the scaling factor has a constant value of 13,000 mg C m^-2. The non-algal component (bbpNAP) is evaluated as the intercept of the linear regression between chlorophyll and bbp(443). The overall aim of this experiment is to provide the ocean colour community with a quantitative baseline for the understanding of the phytoplankton diurnal cycle. This can have strong implications in the context of geostationary ocean colour remote sensing. The phytoplankton vertical distribution over time is here analysed with respect to standard physical measurements.