The EPIGRAM project concerns the dynamics of the French Atlantic marginal and coastal areas (Bay of Biscay and Channel). It is indeed noticeable that most of the researches on the dynamics of the ocean have concentrated on the deep ocean, and its low frequency (climate) variability. The coastal area has only driven back our attention in this field recently, thanks to the development of coastal operational oceanography, and the need for a better monitoring of this area for economical, health or military purposes. One of the main scientific lag is associated with observations at sea: there do not exist 'heavy' campaigns at sea covering this area, and most of the scientific data were collected 15 years ago or more. The project is therefore based on: The definition, realisation and exploitation of campaigns at sea, performed by IFREMER, CNRS/INSU and SHOM. The construction of realistic numerical models of the area, and their comparison with observations at sea, on the basis of process studies. The processes selected for this project are high frequency to seasonal variability at the most. We will concentrate on hydrodynamical studies and the main scientific goal is to improve our comprehension of the main dynamical processes of the continental shelf and margins in the 'Manche' (Channel) and 'Golfe de Gascogne' (Bay of Biscay) and the ability of the numerical models to represent them. The project gathers 14 oceanographic public laboratories with about 50 people. The expected outcomes of the project are: The realisation of four important campaigns at sea and the collection of data for all selected processes. The scientific analysis of the collected data (furniture of diagnostics for all selected processes). Validated realistic numerical models of the area (whose results will be compared to -and limits will be assessed from comparison with- observations at sea). An improved understanding of the major physical processes of the area. In summary, the present project is proposed for a four years period. It concentrates on the physics of the Bay of Biscay and the Channel, in particular on the continental shelf and margin dynamics. It is based on the definition and exploitation of campaigns at sea and numerical modelling studies. The general goal being to improve our understanding and modelling capacity of selected physical processes. These results will be of primary importance for the oceanographic scientific community in general and for nowcast/forecast operational systems. Finally the chosen approach (built on the analysis of oceanic processes) will also facilitate the extension of the results gathered on the present project to other regions.

Coastal zones are essential for social and economical developments. Located at the interface between ocean and continent, the coasts are vulnerable to environmental hazard and are currently facing an intensification of risk associated with increasing human pressure and the context of global climate change. This project focuses on two regions of the world particularly exposed to coastal vulnerability: West Africa and Vietnam. The environmental conditions governing hydro-sedimentary functioning differ drastically between the two regions. Erosion in West Africa is induced all year long by high-energy long swells; in contrast, Vietnam shows paroxystic events induced by typhoons. Even though the societal issues are manifest in these areas, their hydro-sedimentary functioning remains poorly known and limits social and economical development. The objective of the COASTVAR project is to advance our understanding by characterizing the morphological evolution (aerial and submerged), the driving forces and hydro-morphodynamic processes, from event to seasonal and interannual scales. Emphasis will be given to extreme events and their long-term effect, and to surf-shelf exchanges associated with the wave-induced circulation. In the first project task, innovative observational tools (video imagery and drone) will be used in addition to conventional instruments. In a second task, deep-water wave conditions will be downscaled to the beach, then nearshore configurations of a 3D coupled wave-current model will be set up. In a third task, the ECORS beach evolution predictor (PEA SHOM-DGA), which was yet only tested in mid-latitude environments, will be applied for the first time to tropical coastal systems. Our objective here is to obtain a generic operational tool that can be applied to any coast in the world. The research developed in the COASTVAR project has a strong dual aspect. First, it will provide the first high quality survey and forecasting system for the selected regions (waves, currents and bathymetry), which will be highly relevant to military action. Then, it will propose tools to anticipate coastal risks (erosion and submersion), quantify vulnerability and exposure of people to hazard, and lay solid grounds to improve coastal management.

Knowing the gravity field and the geoid in coastal areas is a challenge of primary importance, in order to comprehend the coastal environment and its dynamics, for instance for studying the coastal currents from altimetric measurements, for the determination of the geodetic and hydrographic references, for the exploitation of natural ressources and for passive navigation. For that aim, it is necessary to homogeneize and densify the gravimetric coverage in the whole land-sea transition area, given the heterogeneity of the present coverage and the lask of land-sea continuity. In this context, the objective of this project is to study the interest of airborne planar gradiometry, as a complement to the existing surface gravity data (on land and at sea) and to the GOCE satellite gradiometry data, for the determination of the gravity field and the understanding of the coastal environment. This projects aims at determining the conditions to be fulfilled by 1) a planar electrostatic gradiometer based on the electrostatic accelerometers from the CHAMP, GRACE and GOCE missions, taking into account the precision on the positioning and attitude control of the plane, and 2) the gradiometer decoupling platform that allows to separate the gradiometric measurement from the carrier noise and is a key element of the system. This project will thus allow us to conclude on the feasability of such system and its scientific interest. This project is aimed to support an ONERA PhD thesis for which an application for complementary funding is being submitted to DGA.

In this project, we propose to build a transportable optical clock based on ytterbium atoms and to explore applications of this device to geodesy and geodynamics. The frequency of an atomic clock being sensitive to the geopotential caused by mass distribution , measuring the frequency shift between two clocks can be interpreted in terms of potential difference, or height difference. The perspective of controlling the clock frequency at the level of 18 significant digits is now a reality, which opens the possibility of measuring height differences at the cm level, or equivalent geopotential variations at 0.1 m2/s2 . In parallel, the deployment of optical fiber networks in charge of disseminating an ultrastable reference at 1542 nm is ongoing across Europe, and particularly in France where it takes the form of the Equipex REFIMEVE+. In the future, the transportable clock will enable the resolution of height changes at the 1 cm level between a reference point and any access point to this European networks, even for distances of several thousands of kilometers. Such a measurement is presently unreachable for any instrument, ground-based or in orbit around the Earth. These unprecedented measurements will lead to disruptive applications in operational geodesy and in Earth Sciences. In operational geodesy, accurate and high-resolution measurements of height differences over long distances will enable the correction of biases specific to traditional leveling methods. It will also build homogeneous height references at continental scales. Moreover, a better knowledge of geopotential differences will considerably improve the mapping of the equipotential surfaces of the gravity potential , particularly the reference corresponding to the mean sea level, called the geoid. This will have an impact on the determination of marine references, and on studies of coastal currents. Additionally, considering the original spectrum (range of several 100 km) of clock-based measurements compared to usual gravimetric surveys, the monitoring of geopotential variations in a given location will give access to underground deep mass transfers due to many phenomena (tectonic deformation, volcanism, seismic cycle, or change of the mean sea level …). These aspects can possibly increase public awareness of natural hazards and draw the attention of top decision makers. Countless technological and conceptual challenges must be tackled to transfer a device as precise as an atomic clock from a well-controlled lab environment to outdoor uncontrolled conditions. Several approaches are presented in the ROYMAGE project, notably to preserve the stability and the low uncertainty, to reduce electrical consumption, and to reference all the instruments attached to the clock only to the ultrastable 1542 nm carrier provided by the European fiber network. To this end, we propose innovative techniques of seismometers-assisted vibration compensation, of dual Ytterbium clouds to minimize deadtimes, or of “bootstrapping” of an optical frequency comb permanently attached to the device. The clock will be assembled at SYRTE (Observatoire de Paris), and prior to transport at nodes of the European fiber link, metrological performances will be assessed by comparison to the 6 atomic clocks (strontium, mercury, cesium) already operational in the laboratory. To conclude, the project aims at building the core of the clock, demonstrate the feasibility of the instrument, and evaluate its possible impact for targeted applications. The consortium submitting the proposal gathers specialists of quantum technologies, of geodesy and geophysics, and operational experts in terrestrial and marine geodetic references..

The quantification of suspended matter concentrations and fluxes is a major challenge in order to better understand the role of coastal areas in the storage and transfer of matter to the deep ocean. These materials concern the elements of biogeochemical cycles (C, N, P, P, Si,...) but also the organic materials, nutrients and contaminants that control and influence the functioning of coastal ecosystems. These material fluxes occur mainly during intense meteorological events (floods and storms) from the catchment areas to the coastal zone where they are temporarily stored and then exported by currents and tides. However, there are very few measurements of these fluxes during intense events and are mainly derived from measurements from satellite images, buoys and other fixed anchorages. The ASTRID-MATURATION "MELANGE" project (real-time Measurement of sEdiment fLuxes in coAstal zoNe using GlidErs) is a follow-up to the ASTRID "MATUGLI" project (autonomous Measurements of coAstal TUrbidity using GLIders) during which was developed a prototype glider for autonomous turbidity measurements. Within the framework of the MELANGE project, it is planned to make this prototype more reliable with the help of an industrialist (ALSEAMAR) and an PME (CENTRALWEB) in order to produce a tool capable of measuring and transmitting measurements of current, turbidity and in fine material fluxes at various spatial (from metre to hundred kilometres) and temporal (from second to several months) scales of the coastal zone. This tool could eventually be used to monitor coastal water quality under the Water Framework Directive and the Marine Environment Strategy Framework Directive for marine parks, for example, and to monitor underwater current and visibility for military applications, but these data will also be used to feed hydrodynamic models for coastal forecasting.