In global geodynamics, one of the most striking events is the transition from continental rifting to oceanic spreading, as most of the involved parameters fundamentally change (rift to drift, mantle source of magmas, nature of the lithosphere, magmatic plumbing system architecture, hydrothermal system). Despite their importance for the Earth geodynamics, the processes that govern the initiation of oceanic spreading and the associated production of juvenile magmatic crust remain first order open questions for the international geo-community. Few quantitative constraints exist on how magmatic spreading initiates to form steady MOR? In other words: How and when typical magmato/tectonic processes of oceanic spreading are gradually emplaced during Ocean Continent Transition (OCT) stage? Ultimately, why, at a certain moment, continental thinning switch to magmatic accretion and initiates the break-up? These fundamental questions could be tackled either by models (numerical or analogic) or following quantitative documentation of processes on fossil OCT and/or on active mature rifts, that can be viewed as nascent MOR. The Afar region at the northern end of the East African Rift system is the unique place on Earth where magmatic continental rifting and associated ongoing break-up processes are exposed onshore. This magmatic rift system is dissecting a Large Igneous Province and is connected laterally to the Red Sea and Gulf of Aden oceanic spreading ridges. This system presents the key advantage to expose extensional structures considered at ocean-continent transition with magmatic segments characterized by contrasted morphologies, magmato-tectonic styles, and maturity that have tentatively been assimilated to proto-spreading centers. The main working hypothesis of this project is that Afar is presently experiencing the final stage of continental break-up and progressive onset of steady magmatic spreading (process already completed in the lateral Red Sea and Gulf of Aden). The three main active, contrasted and complementary magmatic segments of Afar (Erta Ale, Dabbahu-Manda Hararo, Assal) offer the opportunity to study mantle and crustal processes in order to decipher fundamental parameters that control focussing of tectonic and magmatic activity until complete removal of continental lithosphere. The MAGMAFAR project is designed to make a breakthrough into this key and first order fundamental scientific issue of continental break-up in magmatic context, and rift transition to the onset of MOR. We will particularly focus on: (i) how do magmatic and tectonic processes control the styles and morphologies of magmatic segments? what are the parameters responsible for the characteristics of proto, steady-state spreading processes? (ii) why and how stable magma production and organized/focussed transfer to the crust start and led to break-up? Along the active magmatic segments of Afar we still need to understand precisely: how magmas are generated? how they are transferred to the crust? how they interact and are controlled by other forcing parameters (in particular, the mechanical behavior of the lithosphere)? We elaborated a general strategy that will combine high resolution quantification of both tectonic and igneous processes in the (i) active and (ii) plio-quaternary natural systems, which will serve in turn to calibrate (iii) an integrated thermo-mechanical modelling. Such an integrated and multidisciplinary approach, based on the combination of numerous complementary skills (petrology / geochemistry / geochronology / remote-sensing / structural geology / thermomechanical modelling), will be focused on the comprehensive description of these unique active segments, in order to bridge timescales and processes across the entire Afar Rift System. The MAGMAFAR project will produce a significant number of deliverables that will gradually cover the description and understanding of magmatic OCT from individual processes to general models.

Extreme heavy precipitation events (HPEs) pose a threat to human life but remain difficult to predict. Considerable efforts to improve the skill of the forecasts for such severe events have been made in recent years and significant progress has been realized through the development of convection-permitting numerical weather prediction systems (NWPS). However, our ability to predict such high-impact events remains limited because of the lack of adequate high frequency, high resolution water vapor (WV) observations in the low troposphere (below 3 km). HPEs occurring in small and steep watersheds are responsible for the triggering of flash floods with a sudden and often violent onset and rapid rising time, typically from 1 to 6 h following the causative rainfall. We aim to implement an integrated prediction tool, coupling network measurements of WV profiles and a numerical weather prediction model to precisely estimate the amount, timing and location of rainfall associated with HPEs in southern France (struck by ~7 HPEs per year during the fall). The proposed WaLiNeAs project is a unique, innovative initiative that will for the first time ever allow assimilating high vertical resolution lidar-derived WV profiles in the first 3 km of the troposphere. The benefit of WaLiNeAs to the academic and operational communities is dual: advance knowledge of the complex dynamical and dynamical processes controlling the life cycle of HPEs and enhance the predictability of HPEs in southern France at scales relevant for meteorological studies. Both aspects are dealt with in the framework of WaLiNeAs. A network of 5 autonomous Raman WV lidars will be deployed in the Western Mediterranean to provide measurements with high vertical resolution and accuracy, closing critical gaps in lower troposphere WV observations by current operational networks and satellites. Near real-time processing and ensemble assimilation of the WV data in the French operational Application of Research to Operations at MEsoscale (AROME) model, using a 4DEnVar approach with 15 min updates, is expected to enhance the model capability for kilometer-scale prediction of HPEs over southern France 48 hours in advance. The field campaign is scheduled to start early September 2022, to cover the period most propitious to heavy precipitation events in southern France. The Raman WV lidar network will be operated by a consortium of French, German and Italian research groups. Lidar data will be made available to Météo-France shortly after being acquired up to 96 times per day. Besides demonstrating the potential of WV lidar data assimilation in a near real-time operational context, an ancillary objective of the project is also to show that Raman lidars can be left to operate continuously almost unattended for a period of at least 3 months. It is a prerequisite in the perspective of future deployment of operational Raman lidar systems meant to fulfil the observational gaps in WV in the lower troposphere of the current operational observation networks and satellites. This project will lead to recommendations on the lidar data processing for future operational exploitation in NWPS. This project will contribute significantly to the scientific objectives of CES04 « Innovations scientifiques et technologiques pour accompagner la transition écologique » through the development of all-weather, unattended, continuous operation of Raman lidar systems for smart monitoring of the environment, and WV in particular. This project is highly innovative and will lay the foundation for a future integrated warning tool aiming to prevent natural hazards associated with heavy precipitation events as often experienced along the Mediterranean coastline. Once the proof of concept is validated in the framework of the WaLiNeAs project, similar integrated tools may be applied in other parts of the World to avoid similar natural hazards.

Understanding, modeling, forecasting and reconstructing fine-scale and large-scale processes and their interactions are among the key scientific challenges in ocean-atmosphere science. Artificial Intelligence (AI) technologies and models open new paradigms to address poorly-resolved or poorly-observed processes in ocean-atmosphere science from the in-depth exploration of available observation and simulation big data. In this context, this proposal aims to bridge the physical model-driven paradigm underlying ocean & atmosphere science and AI paradigms with a view to developing geophysically-sound learning-based and data-driven representations of geophysical flows accounting for their key features (e.g., chaos, extremes, high-dimensionality). We specifically address three key methodological questions: (i) How to learn physically-sound representations of geophysical flows? (ii) Which learning paradigms for the representation of geophysical extremes? (iii) how to learn computationally-efficient representations and algorithms for data assimilation?. Upper ocean dynamics will provide the scientifically-sound sandbox for evaluating and demonstrating the relevance of these learning-based paradigms to address model-to-observation and/or sampling gaps for the modeling, forecasting and reconstruction of imperfectly or unobserved geophysical random flows. To implement these objectives, we gather a transdisciplinary expertise in Numerical Methods (INRIA GRA & Rennes), Applied Statistics (IMT, LSCE), Artificial Intelligence (IMT, LIP6) and Ocean and Atmosphere Science (IGE, INRIA GRA, LOPS), complemented by the participation of two SMEs (Ocean Data Lab and Ocean Next) to anticipate the added value of AI technologies in future earth observation missions and coupled observation-simulation systems.

Surface winds over Antarctica are among the strongest and most persistent on Earth. These winds profoundly shape the surface conditions on the ice sheet, breaking the surface temperature inversion, and transporting snow. Coupled climate models used for IPCC projections have too low resolution to reproduce the katabatic forcing, and as a result, projections assume that katabatic winds are stationary in time. However, there are too few sustained observations to precisely describe the temporal variability of Antarctic surface winds. Here we propose to give new insight on surface wind variability by (1) developing a proxy for wind intensity in ice cores and providing the first wind reconstruction at decadal scale for the past 1000 years, (2) studying the drivers of surface wind intensity and the impact of climate change in the polar oriented regional model MAR, and (3) providing new observational constraints on the impact of katabatic winds on the near surface snow and moisture transport.

The Notre-Dame de Paris (NDP) wooden oak frame is one of the greatest masterpieces of Gothic carpentry in France. It was constructed during the High Middle Ages (HMA) between the 11th and 13th centuries, at a time of profound environmental and societal changes – climate optimum, strong demographic and economic growth – which created significant pressure on available forest resources, one of the key economic drivers of medieval societies. The destruction of the NDP wood framework in the fire of 15 April 2019 left thousands of charred and fragmented oak wood pieces. Analyzing this "forest" means to almost go back in time, by rebuilding the forests of past centuries and restoring this heritage for the public. The CASIMODO project aims to understand the impact of climatic and anthropogenic factors on the evolution of the HMA forest–wood socio-ecosystem: forest, raw wood material management, and manufactured end products in the Île-de-France and Paris Basin. The project proposes three lines of research to address society’s adaptive response to the availability of wood resources during the HMA. The first purpose is to define the climatic and the socio-economical context of Paris. In order to identify the potential technical adaptations of the medieval society, the second objective is to study the timber and destroyed framework from an archaeological point of view in order to characterize the construction supply methods of the building site. The third purpose consists of characterizing the forest stands exploited in the 11th–13th c., their management, and the possible silvicultural systems used for the production of adequate timber. The overall goal of CASIMODO is to provide crucial information and enable a fuller understanding of the evolution of an economic area under climatic, societal and demographic pressure, through the wood life cycle. We propose to develop an integrated approach by combining history, archaeology and bioarchaeology. Trees record variations in environmental variables, with each annual growth ring containing a means of dating, and a set of anatomical and chemical markers indicators providing information of the woodland structure, the geographical origin of the wood, and past climate. This information will be compared with contemporaneous wood data from secular and religious medieval frames from Northern France, Southern Belgium and Western Germany. Complementary proxies, such as textual archives and paleoenvironmental/bioarchaeological data of medieval archaeological sites in the Île-de-France and Paris Basin will also be integrated. By echoing the context of the current ecological threat, this project addresses recurring problems in human–nature relations and is in line with the theme of societies facing environmental change. Improved documentation of temporal and spatial variability in past global climates is needed to better anticipate the possible impacts of future climate change. CASIMODO can provide indirect clues on the extent of deforestation or even natural disasters and linked epidemics such as the plague. In addition, radiocarbone dating is a central tool of modern science (biology, ecology, geology, history, archaeology.); however, it is still hampered by the imprecision of dates obtained for certain periods. Progress in this direction will, therefore, be a major step forward for very large section of the scientific community