POSTER SESSION 2
10:30–12:30, Tuesday, September 15
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
ABSTRACT 1183 | POSTER 22
DIURNAL PHYTOPLANKTON FLUORESCENCE DYNAMICS REVEALED BY FINE SPECTRAL FEATURES IN ATMOSPHERIC ABSORPTION BANDS USING HYPERNETS DATA
In the context of FLEX satellite mission, which aims to study sun-induced fluorescence (SIF) of both terrestrial vegetation and marine phytoplankton, the understanding and retrieval of fluorescence have become increasingly important. In water, chlorophyll-a fluorescence is a signal emitted between 640 and 800 nanometers which indicates the photo-physiological state of phytoplankton, it is also useful to better constrain primary production. Since the 1970s, SIF has been studied over land, where it has been identified as an infilling of Fraunhofer absorption bands, leading to the development of the Fraunhofer Line Depth (FLD) method to estimate fluorescence. Then, numerous retrieval algorithms were developed to improve SIF estimation accuracy, such as FLD-based methods or spectral fitting ones. Primarily designed for terrestrial vegetation, these methods could also provide new information on phytoplankton physiological state. This study shows how fluorescence might be extracted from hyperspectral radiometric measurements thanks to high spectral resolution sensors. The HYPSTAR instrument, deployed within the WaterHYPERNETS network, was exploited to demonstrate feasibility to retrieve fine spectral features of fluorescence in-filling process occurring in Fraunhofer and telluric absorption bands, especially within the dioxygen bands where chlorophyll-a fluorescence is the most significant. Based on these results, diurnal variations were observed on several WaterHYPERNETS sites, indicating dynamics consistent with non-photochemical quenching. This study across various sites has also shown in-filling processes in other absorption bands than the ones of dioxygen, likely highlighting fluorescence from dissolved organic matter or from pigments other than chlorophyll-a, potentially phycobiliproteins, providing supplementary information for water quality mapping from space.
Zoé Besnard*, Nantes University, [email protected]
Tristan Harmel, Magellium Artal Group, [email protected]
David Doxaran, Laboratoire Océanographie Villefranche, [email protected]
Soham Mukherjee, Magellium Artal Group, SABER, [email protected]
Pierre Gernez, ISOMer Université de Nantes, [email protected]
Poster Session | 1 | 2 | 3 | 4 | Schedule at a Glance
