Biography：
Prof. David Antoine currently leads the Remote Sensing and Satellite Research Group at Curtin university, Perth, Western Australia, after having developed a research career at the Oceanography Laboratory of Villefranche sur mer, France. He holds a PhD in oceanography from the University Pierre et Marie Curie, Paris (now “Sorbonne University”). His research over years has encompassed a number of topics from marine optics to satellite ocean colour remote sensing, all together aiming at better quantifying phytoplankton in the oceans, their productivity, and their long-term changes in response to environmental changes. He developed a unique >20 years ocean time series program collecting optical and biogeochemical data in support to research and to validation of satellite ocean colour observations (called "BOUSSOLE"; Mediterranean Sea). After moving to Australia in 2013 he refocused his research on the Southern Ocean in particular. He also has had an enduring implication in international coordination and training activities, largely through the International Ocean-Colour Coordinating Group (IOCCG), the French space agency (CNES), the European Space Agency’ senior Earth Science Advisory Committee and, more recently, with the Australian space agency and the Earth Observation Australia (EOA) advocacy and coordination group.
Abstract：
Due to its harsh environment and remoteness, the Southern Ocean (SO) remains poorly observed and understood, in particular about bio-optical properties. This presentation will summarise our recent findings about these properties and their relationships to ecologically and optically important variables, namely the phytoplankton chlorophyll 
(Chl) and the particulate organic carbon (POC) concentrations. The properties we examined are the particulate absorption coefficient (
), the particulate backscattering coefficient (
) and the absorption by coloured dissolved organic matter, or “yellow substances” (ay). This work was based on field measurements both ship-based and from autonomous profiling Biogeochemical-Argo floats (BGC-Argo).
Similar to previous studies we found that the chlorophyll-specific phytoplankton absorption coefficient is lower than in other oceans at comparable chlorophyll concentrations. This appears to be driven in part by lower concentrations of accessory pigments per unit chlorophyll a as well as increased pigment packaging due to relatively larger sized phytoplankton at low chlorophyll a than is typically observed in other oceans.
In the clearest waters of the SO (Chl < 0.2 mg m−3), we also found a large contribution to absorption by non-algal particles at 442 nm, up to 10 times the absorption of phytoplankton, making the particulate bio-optical properties there remarkably different from typical oceanic case 1 waters. For waters with Chl > 0.2 mg m−3, no significant differences are noticed between the SO and temperate waters.
As for 
in surface waters, we derived it from the diffuse attenuation coefficient (
) derived from radiometric measurements performed by BGC-Argo floats. Our derived vs. chlorophyll-
concentration (Chl) relationships in the SO diverge what they are for low-latitude waters, with a larger relative contribution of 
to the absorption budget for clear waters (Chl < ~0.2 mg m–3) and the opposite for greener waters, leading to a weaker dependence of on Chl. Lower-than-expected CDOM absorption mostly happens during the austral summer, suggesting significant photobleaching or lower biologically-mediated production. The relative contributions of CDOM and phytoplankton to the absorption budget are also found to diverge from what bio-optical models predict, with implication for interpretation of satellite ocean colour observations in the SO.
