The development of observing systems for the global ocean relies heavily on data provided by satellite observations, especially observations of the so-called "ocean colour" (visible and near infrared radiometry, VSR). Two parallel efforts must be supported in this context. The first one is to ensure continuity and quality of observations for parameters that we now derive from such observations. The second one is to conduct basic research necessary for (1) a better understanding of relationships between geophysical variability and the optical signals measured in situ and by satellite sensors and, (2) establishing the link between bio-optics, biogeochemistry and estimation of carbon fluxes. This second aspect is essential to gradually improve the scientific relevance of products from satellite observation, and therefore the quality of observing systems and their operational aspects.
The project proposed here follows this approach. It is proposed to exploit optical and biogeochemical observations made over 6 years at high frequency at the BOUSSOLE site in the north-western Mediterranean (Ligurian Sea), and to complement them with new parameters, to study in particular the variability at the diurnal scale. This diurnal variability is relatively little studied, although it is a key driver of physics of the upper oceanic layers and of the biological activity that develops in these upper lit layers. It is also a main cause of the "noise" observed in the bio-optical relationships derived from data collected in the global ocean. Observations made at high spectral resolution will also be used to study changes in bio-optical regimes and their relationship with the composition of the microbial ecosystem.
The logic behind this project is to address the variability of bio-optical regimes, not from global databases built from point measurements made during cruises necessarily localized in time and space, but from a database consisting of a continuous time series at high frequency. There are at least three advantages to do this. First, measurements at high frequency allow exploring all time scales greater than or equal to the frequency of measurement (hour, day, month, season, etc ...). Taking into account the time scale of measurements is essential in their interpretation. Continuous measurements also provide a context for each observation, which may facilitate the interpretation of each particular situation (which is impossible from discrete measurements made locally). As indicated above, the high frequency is also the only way to study the diel scale. The BOUSSOLE database contains all optical and biogeochemical data needed for this study.
The BOUSSOLE project has been funded for 10 years by space agencies (CNES, ESA and NASA). This support, combined with the institutional support from INSU and CNRS (salaries and ship time), allows maintaining routine operations, e.g., providing data for the calibration and validation of satellite sensors, but is insufficient to fully develop the science aspect of the project. The purpose of the present research proposal is to take a major step in the scientific exploitation of a unique database (in terms of content, duration and quality), to renew our understanding of global bio-optic variability and to assess the biogeochemical implications and applications that derive from this.
UNIVERSITE PIERRE ET MARIE CURIE (Paris 6) (Laboratoire public)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - Délégation Ile de France Ouest et Nord
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - Délégation Alpes
CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - Délégation Paris B
UNIVERSITE PIERRE ET MARIE CURIE (Paris 6)
Help of the ANR 630,000 euros
Beginning and duration of the scientific project: - 48 Months