The proposed project aims at developing a novel in-situ observing system to expand measurements of the Earth’s atmosphere with a focus on boundary layer processes. VOLTIGE (Vecteurs d’Observation de La Troposphère pour l'Investigation et la Gestion de l'Environnement) is a French word for aerobatics or stunt flying; and the acronym translates to ‘Tropospheric Observing System for the Investigation and Management of the Environnement’. To date, radiosondes are the only routine in-situ means of profiling the earth’s atmosphere – and with a very limited set of sensors (temperature, relative humidity and pressure). To address the scientific and technical challenges related to observing the atmosphere, the proposed project is centered on unmanned aerial systems (UAS) for scientific and civilian applications. Atmospheric research and forecasting models have long suffered from a gap between ground-based and satellite-based measurements of the atmosphere. As a consequence certain atmospheric phenomenon, such as aerosol-cloud interactions, remains one of the largest uncertainties in understanding climate change. On regional and shorter time scales compared to climate change, adverse weather conditions also pose risks to the transportation industry, particularly when visibility is reduced. Future improvements in numerical weather prediction and climate simulations rely on systematic observations of atmospheric parameters to characterize the vertical dimension and to improve integration of in-situ measurements and satellite observations. VOLTIGE strives to fill a niche for UAS by developing autonomous profiling capability and coordinated observations – introducing a re-usable sonde that contains a variety of sensors to address a particular science theme (e.g., fog life cycle). This project has two major objectives: 1) increase our scientific capacity to observe the atmosphere and surface of the Earth; and 2) engage students to the recent technological advances in meteorology and aeronautics. Of specific interest in VOLTIGE, the proposed project builds on existing observational capabilities to observe the major parameters related to fog cycles via an integrated network of sensors. The occurrence of fog events are of great concern for airport operators and air transport companies. However, forecasting of fog events is still a major challenge because numerical simulations lack sufficient information to predict or reproduce fog events using classical meteorological models. Most fog studies are limited to ground-based measurements that utilize remote sensing techniques to explore the vertical structure. Currently, in-situ airborne measurements of fogs are only possible with balloons and the applications of balloons for fog research have been scarce. VOLTIGE develops the tools to build an observational capability that extends beyond the specific science applications proposed here. Hence, by coupling novel technology with innovative science, this project engages a future generation of scientists and engineers at the École Nationale de Météorologie (ENM) and the INP-École Nationale de l’Aviation Civile (ENAC). The application of VOLTIGE in an operational network will be integral to the education of students at ENAC and INP-ENM. These low-cost systems may be deployed for eventual operational use for meteorological forecasts and surveillance of toxic plumes in case of industrial accident or volcanic ash plume. If successful, this project will further establish lightweight UAS as viable and cost-effective observing platforms for environmental sciences.

The semi-arid regions of the Earth are particularly susceptible to wind erosion. Low annual precipitation rates, often combined with long periods of drought during the year, lead to a sparse herbaceous vegetation, with annual density varying from one year to another, and a stand sparse woody plant cover whose density can largely vary over the years. These vegetated surfaces in the Sahel are usually dedicated to pastoral livestock but are increasingly used for agricultural purposes. As a result, a significant proportion of the land is bare or sparsely vegetated, and thus not efficiently protected from the erosive action of wind. In this region, wind erosion tends to decrease the productive capacity of the soils whose fertility is already very low. In addition, the impact of wind erosion is expected to increase significantly in the next future (1) in relation with the expected changes in climate (in the particular modifications of the precipitation and surface wind fields) and (2) in response to the increasing land use due to population increase and the related food needs. The project aims to develop an integrated modeling tool to describe the evolution of wind erosion in the Sahel in connection with climatic changes and land use, to validate this tool in the current period by making the best possible use of the numerous data sets acquired in recent years over West Africa and to test its ability to reproduce specific events (such as the drought in the Sahel) of the recent past (about the last 50 years). This project is based on a simulation approach of this recent past (hindcasts) that is justified by the need to ensure the robustness simulations under conditions with different forcings, prior to any simulation of future scenarios. The proposed strategy is (1) to develop / optimize / couple reliable modeling tools for quantifying the various terms (land use, changes in aridity ...) responsible for changes in the intensity of wind erosion ( 2) to synthesize quality-checked observations for the studied period, that can be used as direct or indirect indicators of wind erosion (precipitation time series, changes in vegetation cover, atmospheric dust load ...) (3) implement a validation strategy based on the quantification of wind erosion both locally measured on grazed and cultivated plots and at the regional and continental scale (using proxies like the dust content of the atmosphere).

The Mediterranean basin has quite a unique character that results both from physiographic and climatic conditions and historical and societal developments. Because of the latitudes it covers, the Mediterranean basin is a transition area under the influence of both mid-latitudes and tropical variability. Because in such transition area, the Mediterranean basin is very sensitive to global climate change at short (decadal) and long (millennial) time scales. Regarding on-going climate change, the Mediterranean area is considered as one major “hot-spots” with an increase in the interannual rainfall variability and strong warming and drying. The vulnerability of the Mediterranean population may thus increase with higher probability of occurrence of events conducive to floods and droughts which are among the most devastating natural hazards. In the context of global warming, sea level rise is also of major concern since the Mediterranean basin has one of the most crowded coasts in the world and demographic projections suggest that urban coastal population could reach 176 million people and the number of tourists per year could grow up to 350 million by 2025. This continuing migration towards coastal areas makes the Mediterranean one of the most vulnerable region to risks inherent to rising sea level. The motivation of the project is thus to understand and model the Mediterranean climate system and specifically the processes leading to heavy precipitation and floods, heat waves and droughts and sea-level rise, not only as separate processes within each Earth compartment, but as coupled mechanisms with feedback loops. This is indeed crucial to characterize how these processes will respond to climate change, in order to make decision on development of adaptation strategies to face risks related to changing climate. First, it relies on the analysis of a first set of simulations performed with the three French stand-alone and coupled regional climate models in the frame of HyMeX and MED-CORDEX programs (stream1 simulations) and on the quantification of the multi-model uncertainty. Second, it consists in improving the stand-alone models with new common parameterizations for precipitation and air/sea fluxes, and river routing, multi-layer soil, groundwater, vegetation, irrigation and sea-level schemes. Last, it consists in integration these improvements in regional climate system models to produce and analyse a new set of regional simulations (hindcasts and IPCC CMIP5 scenarios) for the Mediterranean climate (stream 2 simulations) which will hopefully better represents heavy precipitation and floods, heat waves and droughts and sea-level evolution. However, regional climate simulations are often biased and correction methods have to be applied to provide relevant information for end-users. Modelling the full climate systems by coupling sophisticated models of the different compartments is an a priori necessity to accurately simulate the regional climate but biases of each model can propagate and therefore affect the simulated regional climate. A last objective of the project is thus to quantify the potential added-value of fully coupled regional climate system models with respect to stand-alone regional climate models to provide relevant indicators to provide information tailored to the needs of policymakers and society actors. The REMEMBER project will make use of the new observation datasets collected in the frame of HyMeX and can be seen as the French contribution and support to the HyMeX and MED-CORDEX programs. This project is thus to be conducted in strong collaboration with European and Mediterranean partners and will benefit from the visibility of such programs for the dissemination of the results.

As pointed out by international organizations and an abundant scientific literature, water is a strategic issue in the Mediterranean region, mainly because of the rarefaction of the resources, in quantity and/or quality, facing the ever increasing demand and the problem of sharing water scarcity. Vulnerability linked with water is paramount in the semi-arid North Africa, where climatic hazards and environmental changes induced by human activities reinforce the likelihood of crises, and where the unequal distribution of resources contributes to increasing the competition between water uses and users. The AMETHYST project aims to analyze the co-evolutions of the water resources under the influence of global change (climate and anthropogenic changes) and of the water uses trajectories. We focus our work on the Maghreb because a large range of evolutions is still possible in this region, far from the extremely severe situations of coastal Spain or Israël on one side, from the reasonably comfortable situations of northern Italy or south-eastern France on the other side. Two case studies will be considered, the Merguellil catchment (near Kairouan, in central Tunisia) and the Tensift region (near Marrakech, Morocco). They are emblematic of water scarcity issues, with rich complementarities in terms of environmental context, water uses, sector competitions, hydraulic history and current water policies. They can also provide large sets of data because of previous long-term research works. We propose an inter-disciplinary project combining physical, social, economic and political sciences, with three research axes: (1) A numerical platform of the integrated functioning of the water resources evolution will be developed, based on models driven by in-situ, reanalysis or scenario data as well as satellite products and anthropogenic constraints arising from the study of the reciprocal impacts of water uses and policy regulations on water resources. (2) Based on a diachronic data analysis and a diagnostic run of this platform, we will analyze the evolution of water resources in the past fifty years in relation to many environmental social, economic, political and technological factors that have interacted. We’ll not only look at trends but also at the way the system reacts after events such as drought or social upheavals. (3) Various scenarios, based on climate and anthropogenic modifications associated with socio-economic projections, will be tested to anticipate effects on water resources trajectories in the next twenty years (extended to fifty years for climate change scenarios), by numerical modeling and by participative approaches. The high ambition of this project is to enhance exchanges between environmental and human sciences at every step of the research, from the acquisition of data to the common definition of prospective scenarios. This shared approach seems the best answer to the urgent water issues in the region, and in particular for providing concrete elements of information to water managers, authorities and stakeholders with whom we will work for the whole duration of the project.