CIRENE Air-Sea Interactions in the Seychelles-Chagos Thermocline Ridge Region

A field experiment in the southwestern Indian Ocean provides new insights into ocean-atmosphere interactions in a key climatic region

EUREC⁴A

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC⁴A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC⁴A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement

EUREC⁴A

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or the life cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso- (200 km) and larger (500 km) scales, roughly 400 h of flight time by four heavily instrumented research aircraft; four global-class research vessels; an advanced ground-based cloud observatory; scores of autonomous observing platforms operating in the upper ocean (nearly 10 000 profiles), lower atmosphere (continuous profiling), and along the air–sea interface; a network of water stable isotopologue measurements; targeted tasking of satellite remote sensing; and modeling with a new generation of weather and climate models. In addition to providing an outline of the novel measurements and their composition into a unified and coordinated campaign, the six distinct scientific facets that EUREC⁴A explored – from North Brazil Current rings to turbulence-induced clustering of cloud droplets and its influence on warm-rain formation – are presented along with an overview of EUREC⁴A's outreach activities, environmental impact, and guidelines for scientific practice. Track data for all platforms are standardized and accessible at https://doi.org/10.25326/165 (Stevens, 2021), and a film documenting the campaign is provided as a video supplement

Exchanges of Kinetic Energy at the Ocean-Atmosphere Interface: A closer look at the Wave-influenced Boundary Layer (WBL) from wind-wave tank data and from a wave-following platform Thirteenth

International audienceRecent investigation of the Turbulent Kinetic Energy (TKE) budget in the Wave-influenced atmospheric Boundary Layer (WBL) from in situ measurements, numerical modelling, and wind-wave tank data.Basic concepts, experimental facility and sea-platform, as well as numerical model abilities are discussed from the point of view of momentum exchange across the air/sea interface, and the value of the imbalance term of the TKE budget due to the wind-wave effect is quantified

Exchanges of Kinetic Energy at the Ocean-Atmosphere Interface: A closer look at the Wave-influenced Boundary Layer (WBL) from wind-wave tank data and from a wave-following platform Thirteenth

International audienceRecent investigation of the Turbulent Kinetic Energy (TKE) budget in the Wave-influenced atmospheric Boundary Layer (WBL) from in situ measurements, numerical modelling, and wind-wave tank data.Basic concepts, experimental facility and sea-platform, as well as numerical model abilities are discussed from the point of view of momentum exchange across the air/sea interface, and the value of the imbalance term of the TKE budget due to the wind-wave effect is quantified

Cereal powdery mildew effectors: a complex toolbox for an obligate pathogen

Highlights • Cereal powdery mildews have evolved a large repertoire of candidate effector proteins. • These effectors are encoded within size variable and highly diversified gene families. • Mildew effectors can act as virulence factors, Avr genes and Avr suppressors. • Their mode of action provides a molecular basis for the Zig-Zag evolutionary model

Design of an offshore three-bladed vertical axis wind turbine for wind tunnel experiments

© 2017 ASME. The rapid shrinkage of fossil fuel sources and contrary fast-growing energy needs of social, industrial and technological enhancements, necessitate the need of different approaches to exploit the various renewable energy sources. Among the several technological alternatives, wind energy is one of the most emerging prospective because of its renewable, sustainable and environment friendly nature, especially at its offshore locations. The recent growth of the offshore wind energy market has significantly increased the technological importance of the offshore vertical axis wind turbines, both as floating or fixed installations. Particularly, the class of liftdriven vertical axis wind turbines is very promising; however, the existing design and technology is not competent enough to meet the global need of offshore wind energy. In this context, the project AEROPITCH co-investigated by EOLFI, CORETI and IRPHE aims at the development of a robust and sophisticated offshore vertical axis wind turbine, which would bring decisive competitive advantage in the offshore wind energy market. In this paper, simulations have been performed on the various airfoils of NACA 4-series, 5-series and Selig profiles at different chord Reynolds numbers of 60000, 100000 and 140000 using double multiple streamtube model with tip loss correction. Based on the power coefficient, the best suitable airfoil S1046 has been selected for a 3-bladed vertical axis wind turbine. Besides the blade profile, the turbine design parameters such as aspect ratio and solidity ratio have also been investigated by varying the diameter and chord of the blade. Further, a series of wind tunnel experiments will be performed on the developed wind turbine, and the implementation of active pitch control in the developed turbine will be investigated in future research

ETUDE D’UN CONTROLE-COMMANDE DE CALAGE DE PALE POUR UNE EOLIENNE OFFSHORE A AXE DE ROTATION VERTICAL

International audienceIn the framework of the PACA Region AEROPITCH contract and the EOLFI project SpinFloat, we have studied the potential benefits of pitching the blades for an offshore vertical axis wind turbine. We built an experimental scale model with a system of three servomotors able to change continuously the angle of wind attack of the three blades continuously during the turbine rotation. Experiments were conducted in the large air-sea wind tunnel of Pytheas Institute in Luminy-Marseille. We have measured the forces, moments, and the rotational speed. We used a particle imaging system (PIV) to characterize the air flow around the blades by a particle imaging system (PIV) with a large seeding particles system. We succeeded to optimize the pitch-control laws to achieve maximum rotational speeds by using a loop optimizer based on genetic algorithm. We then developed CFD numerical simulations taking into account the blade pitching. Numerical results are discussed in comparison with PIV measurements.Dans le cadre du contrat Région PACA AEROPITCH et du projet SpinFloat porté par EOLFI, nous avons étudié les effets que pourraient apporter le contrôle-commande du calage des pales (pitch) pour une éolienne à axe de rotation verticale, à trois pales, destinée à terme à être posée en mer sur un support flottant. Nous avons construit une maquette à l’échelle que nous avons testéedans la grande soufflerie air-mer de l’Institut Pythéas sur Luminy à Marseille. Nous avons conçu un système de servomoteurs permettant de tourner de façon indépendante les trois pales de l’éolienne pour ajuster au mieux l’angle d’attaque des pales par rapport au vent incident à chaque instant de la rotation. Nous avons mesuré les efforts, les vitesses de rotation, et l’écoulement d’air autour des pales par un système d’imagerie de particules (PIV) avec un large système d’ensemencement de particules. Nous avons optimisé des lois de pitch pour atteindre des vitesses de rotation maximales en utilisant une boucle automatique d’optimisation de paramètres par algorithme génétique. Nous avons ensuite développé des simulations numériques CFD prenant en compte le pitchage des pales pendant la rotation. Les résultats numériques sont discutés par comparaison aux mesures PIV