Résumé
OZCAR (Critical Zone Observatories - Application and Research) is a national Research Infrastructure dedicated to providing an integrated understanding of the Earth's surface processes ranging from the subsurface to the lower atmosphere and from high mountains to coastal areas. It includes over 100 highly instrumented sites distributed among 21 observatories for long-term measurements of biological, chemical and physical parameters of groundwater, river water, glaciers, soils, and wetlands in France and overseas. Based on long-term observations at the landscape scale, OZCAR sites address specific environmental question of local societal relevance but all share the same overarching goal of better predicting the response of the Critical Zone to perturbations across a range of timescales.Diversity of OZCAR observation sites allows exploring laterally and vertically all compartments of the CZ from mountains to costal areas. This enables data acquisition on water, soils, agricultural practices and exchanges with the atmosphere. Thus, OZCAR proposes a great variety of models that ultimately will help reproducing observations and predict the evolution of the CZ.Through its wealth of environmental data portal and modelling platerforms, OZCAR aims at advising policy makers and stakeholers on the water, soil, and biodiversity resource.Recently, OZCAR integrated together with the French LTSER network (Zones Ateliers) the pan-European eLTER-ESFRI project.