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International audience The complex vertical distribution of aerosols over coastal southern West Africa (SWA) is investigated using airborne observations and numerical simulations. Observations were gathered on 2 July 2016 offshore of Ghana and Togo, during the field phase of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa project. This was the only flight conducted over the ocean during which a downward-looking lidar was operational. The aerosol loading in the lower troposphere includes emissions from coastal cities (Accra, Lomé, Cotonou, and Lagos) as well as biomass burning aerosol and dust associated with long-range transport from central Africa and the Sahara, respectively. Our results indicate that the aerosol distribution on this day is impacted by subsidence associated with zonal and meridional regional-scale overturning circulations associated with the land–sea surface temperature contrast and orography over Ghana and Togo, as typically observed on hot, cloud-free summer days such as 2 July 2016. Furthermore, we show that the zonal circulation evidenced on 2 July is a persistent feature over the Gulf of Guinea during July 2016. Numerical tracer release experiments highlight the dominance of aged emissions from Accra on the observed pollution plume loadings over the ocean, in the area of aircraft operation. The contribution of aged emission from Lomé and Cotonou is also evident above the marine boundary layer. Given the general direction of the monsoon flow, the tracer experiments indicate no contribution from Lagos emissions to the atmospheric composition of the area west of Cotonou, where our airborne observations were gathered. The tracer plume does not extend very far south over the ocean (i.e. less than 100km from Accra), mostly because emissions are transported northeastward near the surface over land and westward above the marine atmospheric boundary layer. The latter is possible due to interactions between the monsoon flow, complex terrain, and land–sea breeze systems, which support the vertical mixing of the urban pollution. This work sheds light on the complex – and to date undocumented – mechanisms by which coastal shallow circulations can distribute atmospheric pollutants over the densely populated SWA region.

Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air-sea interactions and convective organization.

pour les membres de la Commission scientifique de la Société française de néonatalogie : O. Baud, M. Benard, O. Brissaud, C. Buffat, M.-L. Charkaluk, D. De Luca, G. Favrais, F. Flamein, G. Gascoin, P. Kuhn, E. Lopez ,N. Naassens-Laug, F.Rouget, P. Tourneux, D. Yang, E. Zana-Taieb; This review includes five randomized controlled trials, published in the Medline database in 2015, which were selected by the Scientific commission of the French society of neonatology, taking into account their influence in perinatology. This selection was presented during the specific "Top five" session in the French congress of neonatal research.

International audience; Water vapour measurements from a ground-based Raman lidar and an airborne differential absorption lidar, complemented by high resolution numerical simulations from two mesoscale models (AROME-WMED and Meso-NH), are considered to investigate three transition events from Mistral/Tramontane to southerly marine flow taking place in the Montpellier region (Southern France) in the time frame September-October 2012, during the Hydrological Cycle in the Mediterranean Experiment Special Observation Period 1. Low-level wind reversals associated with these transitions are found to have a strong impact on water vapour transport, leading to a large variability of the water vapour vertical and horizontal distributions. Water vapour mixing ratio within the boundary layer is found to vary from typical values in the range 4–8 g kg−1 during the northerly Mistral/Tramontane flows to values in the range 8–15 g kg−1 during the southerly marine flows. The increase/decrease in water vapour mixing ratio within the boundary layer may be abrupt and marked during these transition periods, with values increasing-decreasing by a factor of 2 to 4 within 1 hour. The high spatial and temporal resolutions of the lidar data allow monitoring the time evolution of the water vapour field during these transitions from predominantly northerly Mistral/Tramontane flow to a predominantly southerly flow, permitting to identify the quite sharp separation between these flows, which is also satisfactorily well captured by the mesoscale models. Water vapour measurements from the ground-based lidar are complemented by particle backscatter measurements from the same system, which allow also revealing the significant variability in the aerosol and cloud fields associated with these transition events.

During Intensive Observation Period 13 (15 to 16 October 2012) of the first Special Observing Period of the Hydrological cycle in the Mediterranean Experiment (HyMeX), Southern Italy (SI) was affected by two consecutive heavy precipitation events (HPEs). Both HPEs were associated with multi-cell V-shaped retrograde regeneration mesoscale convective systems (MCSs). The life cycle of two MCSs in connection with their dynamic and thermodynamic environments were analysed using a combination of ground-based, airborne and spaceborne observations and numerical simulations. Rain gauges revealed that heavy precipitation occurred in two phases: the first one from 1300 to 1700 UTC (35 mm h-1) was caused by a V-shaped system initiating over the Tyrrhenian Sea in the early morning of 15 October. Convection was triggered by the low-level convergence between the southwesterlies ahead of an upper-level trough positioned over southeastern France and very moist southerlies from the Strait of Sicily. The convection was favoured by high convective available potential energy (1500 J kg-1) resulting from warm and moist conditions at low levels associated with high sea surface temperatures in the Strait of Sicily. In addition, humidity at mid-level was enriched by the presence of an elevated moisture plume from tropical Africa, favouring the efficiency of the convection to produce more precipitation. The second phase of heavy precipitation (2300 UTC on 15 October to 0200 UTC on 16 October, 34 mm h-1) was caused by a MCS initiating over Algeria around 1300 UTC, which subsequently travelled over the Strait of Sicily toward Sicily and SI. Convection was maintained by the combination of large low-level moisture contents and a marked convergence ahead of the cold front. Unlike other MCSs forming in the same region earlier on that day, this huge V-shaped system did affect SI because the strong upper-level flow progressively backed from southwesterly to south southwesterly.

The Hydrological Cycle in the Mediterranean Experiment (HyMeX; Drobinski et al., 2014) is a 10-year (2010-2020) GEWEX Hydroclimatology Panel (GHP) Regional Hydroclimate Project (RHP). Its objectives are to: (i) improve the understanding of the water cycle, with emphasis on extreme events, by monitoring and modeling the Mediterranean coupled system (atmosphere-land-ocean), its variability (from the event scale to the seasonal and interannual scales) and characteristics over one decade in the context of global change; and (ii) evaluate societal and economical vulnerability, and adaptation capacity to extreme meteorological and climate events.

International audience; Due to the harshness and inaccessibility of desert regions, the uncertainties concerning the processes of dust mobilization at the surface, airborne transport, and sedimentation are still considerable, limiting the ability to perform model simulations. In June 2011, a comprehensive data set of ground-based and airborne in situ measurements and remote sensing observations was acquired within the Fennec/Lagrangian Dust Source Inversion Experiment (LADUNEX) field campaign in the western Sahara region. Here we evaluate the ability of the state-of-the-art Lagrangian particle dispersion model FLEXPART, newly fitted with a dust mobilization capability, to simulate dust transport in this region. We investigate a case where a large mesoscale convective system (MCS) triggered dust emissions in central Mali, which subsequently moved as a large cold pool dust front toward northern Mauritania. Specifying dust mobilization for this case is shown to be an important obstacle to simulating dust transport during this event, since neither the MCS nor the associated cold pool-causing dust emission is represented in the meteorological analysis. Obtaining a realistic dust transport simulation for this case therefore requires an inversion approach using a manual specification of the dust sources supported by satellite imagery. When compared to in situ and remote sensing data from two aircraft, the Lagrangian dust transport simulations represent the overall shape and evolution of the dust plume well. While accumulation and coarse mode dust are well represented in the simulation, giant mode particles are considerably underestimated. Our results re-emphasize that dust emission associated with deep moist convection remains a key issue for reliable dust model simulations in northern Africa.

International audience

The Convective and Orographically-driven Precipitation Study (COPS) carried out in summer 2007 over northeastern France and southwestern Germany provided a fairly comprehensive description of the low-troposphere water-vapour field, thanks in particular to the deployment of two airborne differential absorption lidar systems. These lidar observations were assimilated using the 3D-Var assimilation system of the Application of Research to Operations at MEsoscale (AROME) numerical weather prediction mesoscale model. The assimilation was carried out for the period 4 July-3 August by running a three-hour forward intermittent assimilation cycle. First, the impact of the lidar observations was assessed by comparing the analyses with a set of more than 200 independent soundings. The lidar observations were found to have a positive impact on the analyses by reducing the dry bias in the first 500 m above ground level and by diminishing the root-mean-square error by roughly 15% in the first km. Then the impact of the lidar observations was assessed by comparing the precipitation forecasts (obtained with and without the lidar observations for the period 15 July-2 August) with the gridded precipitation observations provided by the Vienna Enhanced Resolution Analysis. In general, the impact was found to be positive but not significant for the 24 h precipitation and positive and significant for the 6 h precipitation, with an improvement lasting up to 24 h. Some selected case studies show that the improvement was obtained through a better depiction of convection initiation or through a more accurate positioning of the precipitation systems. © 2011 Royal Meteorological Society.

During summer 2006. the intensity of the thermal depression over the Sahara. derived from European Centre for Medium-range Weather Forecast analyses. exhibited a strong decrease during the first couple of weeks of September Simultaneously. widespread convective activity over the Sahel was detected. The aims of this study are to identify the reasons for this decrease of the West African Heat Low (WAHL) activity, to discuss the possible relationship with convection and to assess the representativity of such an event at the climatological tune-scale. From spectral analysis of the daily WAHL thickness during summer 2006. two period bands of significant intraseasonal pulsations were identified. and confirmed using the ERA-40 reanalysis. namely 3-10d and 10-30d In both the 2006 case-study and the climatological composite study. we find that detrimental conditions in the 3-10d period band are associated with moist and cool advections in the lower troposphere linked to the southerly sector of African easterly waves (AEWs) which increase convective activity over the Sahel These humid and cold advections from the south are more pronounced when the AEW interacts with a midlatitude depression In the 10-30d period band. the impact of midlatitude circulation is demonstrated During the collapsing period of the 10-30d pulsations of the WAHL thickness, an upper-level trough is seen over northern West Africa This situation generates a surge of 700 hPa cold air from Libya into the Sahara. an increase of the 925 hPa anticyclonic circulation and a significant increase of convective activity over the Sahel Copyright (C) 2010 Royal Meteorological Society

Background: While cardiovascular risks associated with high level of ionizing radiation are well-established, long-term effects of low and medium levels of exposure, between 0 and 5 gray (Gy), on the cardiovascular system are debated. Methods: Available literature was reviewed considering various populations, such as survivors of atomic bombs, nuclear workers, Chernobyl liquidators, radiologists and radiological technologists and patients exposed for medical reasons. Results: A significant increased risk of cardiovascular diseases associated with low doses of ionizing radiation was observed in 13 studies among the 27 analyzed. The ischemic heart diseases risk was detailed in 16 studies and seven of them showed a significant increase. The cerebrovascular risk was significantly increased in five studies among the 12 considered. Conclusion: Some epidemiological and experimental data are clearly in favour of an increased cardiovascular risk associated with exposure to low doses. However, given the multifactorial origin of cardiovascular diseases and the lack of a clear pathophysiologic mechanism, epidemiological results have to be carefully interpreted. Further research should be conducted in this area. © 2009 Elsevier Masson SAS. All rights reserved.; Position du problème Si les effets cardiovasculaires des irradiations à fortes doses sont bien établis, les effets à long terme des irradiations à faibles et moyennes doses entre 0 et 5 gray (Gy) sur le système cardiovasculaire restent débattus. Des publications récentes doivent être prises en compte dans cette problématique nécessitant une synthèse des résultats épidémiologiques disponibles à ce jour. Méthodes Cette revue concerne des populations variées, telles que les survivants des explosions atomiques, travailleurs du nucléaire, liquidateurs de Tchernobyl, médecins, personnels navigants et personnes soumises aux rayonnements ionisants d’origine médicale. Résultats Parmi les 27 études analysant globalement le risque cardiovasculaire, un excès lié aux radiations a pu être mis en évidence pour 13 d’entre elles. Les études étudiant le risque cardiaque ischémique retrouvaient une association avec la dose dans sept études sur les 16 analysées. Le risque cérébrovasculaire était significativement augmenté dans cinq études sur les 12 considérées. Conclusion Certaines données épidémiologiques et expérimentales sont clairement en faveur d’un risque cardiovasculaire lié aux irradiations à des faibles doses. Cependant, en raison du caractère multifactoriel des pathologies cardiovasculaires et en l’absence de mécanisme physiopathologique patent, il est nécessaire d’interpréter les résultats épidémiologiques avec prudence et de poursuivre les recherches dans ce domaine.

L'étude des précipitations convectives induites par l'orographie (Cops selon l'acronyme anglais) est un projet international coordonné qui comprend une campagne d'observations de terrain et un programme scientifique et qui vise à améliorer la qualité des prévisions des précipitations orographiques convectives à la fois par l'observation quadridimensionnelle et la modélisation de leur cycle de vie. La campagne de terrain s'est déroulée en juin-juillet-août 2007 sur l'est de la France et le sud-ouest de l'Allemagne. Son objectif majeur était de fournir un jeu d'observations météorologiques, in situ et à distance, aussi complet que possible et sur toute la profondeur de la colonne troposphérique. Après une brève revue d?ensemble du projet, l'article se concentre sur la contribution française à la campagne Cops, décrit le dispositif expérimental mis en oeuvre et met en valeur quelques observations clés. The Convective and Orographicallyinduced Precipitation Study (COPS) is a coordinated international project, comprised of an observational field campaign and a research programme aiming to advance the quality of forecasts of orographically-induced precipitation by four-dimensional observations and modelling of its life cycle. The COPS field campaign took place during June-July-August 2007 over eastern France and south-western Germany. Its main objective was to provide an unprecedented comprehensive set of in situ and remotely-sensed meteorological observations of the entire depth of the troposphere. After a short overview of the project, the paper focuses on the French contribution to the COPS field phase, describes the experimental setup and highlights some key observations.

Purpose of the study: To analyze the effects of external radiation exposure on mortality of French nuclear workers. Method: A cohort of 29,204 workers employed between 1950 and 1994 at the French Atomic Energy Commission (Commissariat à l'énergie atomique: CEA) or at the General Company of Nuclear Fuel (Compagnie Générale des Matières nucléaires: COGEMA, now Areva NC) was followed up for an average of 17.8 years. Standardized Mortality Ratios (SMRs) were computed with reference to French mortality rates. Dose-effect relationships were analyzed through trend tests and Poisson regressions. Results: The mean exposure to X and gamma radiation was 8.3 mSv (16.9 mSv for exposed worker population). A total of 1,842 deaths occurred between 1968 and 1994, for 3,117 expected from the national mortality statistics. Among the 21 main cancer sites studied, a statistically significant excess was observed for skin melanoma, and an excess of borderline statistical significance was observed for multiple myeloma. A dose-effect relationship was observed for leukaemia after exclusion of chronic lymphoid leukaemia (CLL). The relative risk observed for non CLL leukaemia, n = 20, at 100 mSv was 2.2, CI90% = [1.2; 3.3]. Significant dose-effect relationships were also observed for causes of deaths associated with alcohol consumption: mouth and pharynx cancer, cirrhosis and alcoholic psychosis and external causes of death. Conclusion: The risk of leukaemia increases with increasing exposure to external radiation; this is consistent with published results on other nuclear workers cohorts. © 2007. Elsevier Masson SAS.; Objectif Analyser les effets de l’exposition aux rayonnements ionisants sur la mortalité des travailleurs de l’industrie nucléaire. Méthode Une cohorte de 29 204 travailleurs employés entre 1950 et 1994 au Commissariat à l’énergie atomique (CEA) ou à la Compagnie Générale des Matières nucléaires (Cogema, devenue Areva NC) a été suivie pendant 17,8 ans en moyenne. La mortalité de la population a été comparée à celle de la population française par la méthode des rapports de mortalité standardisés (SMR : Standardized Mortality Ratio). L’association entre l’exposition aux rayonnements ionisants et le risque de décès a été analysée par des tests de tendance et par des régressions de Poisson. Résultats L’exposition moyenne cumulée aux rayons X et gamma a été de 8,3 mSv sur la période (16,9 mSv pour la population exposée). Un total de 1 842 décès est survenu entre 1968 et 1994, pour 3 117 décès attendus d’après les statistiques de mortalité nationales. Parmi les 21 localisations de cancer étudiées, il a été observé un excès statistiquement significatif de mélanome malin et un excès de myélome multiple à la limite de la significativité. Une association entre l’exposition aux rayons X et gamma et le risque de leucémie (hors leucémie lymphoïde chronique) a été observée sur la base de 20 décès par leucémie. Le risque relatif estimé pour une exposition de 100 mSv comparé à une exposition nulle était de 2,2, IC90 % = [1,2 ;3,3]. Des relations dose-effet statistiquement significatives ont également été observées pour des causes de décès associées à la consommation d’alcool : cancer de la cavité buccale et du pharynx, cirrhose et psychose alcoolique, et causes externes de décès. Conclusion Le risque de leucémie croît avec la dose de rayons X et gamma au sein de la cohorte. Ceci est cohérent avec les résultats déjà publiés sur l’épidémiologie des travailleurs du nucléaire.

OBJECTIVES: To assess the prognosis of newborn infants with refractory hypoxemia who required extracorporeal membrane oxygenation (ECMO). METHODS: Eighty-nine newborn infants treated by ECMO during more than 24 hours over a 8-year period (1996-2003) were included in this observational cohort study with a 9-month and 24-month evaluation. RESULTS: Respiratory failure mainly resulted from meconium aspiration syndrome (MAS, 43%), congenital diaphragmatic hernia (CDH, 15%) and sepsis (15%). Overall survival at hospital discharge was 67%. Infants with MAS had the best survival rate (82%) and those with CDH had the worst (46%). Of the remaining 60 survivors, 53% remained oxygen dependent at 28 days and 33% at 45 days. At the age of 2 years, only 1 infant remained oxygen dependent (but did not required oxygen at 3 years) and only 3 infants had significant neurodevelopmental problems. CDH group was associated with a prolonged duration in supplementary oxygen (P

The "flux, etat de la mer, et tele'de'tection en conditions de fetch variable'' (FETCH) was aimed at studying the physical processes associated with air-sea exchanges and mesoscale oceanic circulation in a coastal region dominated by frequent strong offshore winds. The experiment took place in March-April 1998 in the northwestern Mediterranean Sea (Gulf of Lion). Observations were collected with the R/V L'Atalante, with an air-sea interaction spar (ASIS) buoy, with waverider buoys, and with research aircraft equipped for in situ and remote sensing measurements. The present paper is an introduction to the following special section, which groups 12 papers (including this one) presenting results on turbulent flux measurements at the ocean surface, on the behavior of the marine atmospheric boundary layer, on the ocean waves characteristics, on the ocean circulation, and on remote sensing of surface parameters. This overview presents the background and objectives of FETCH, the experimental setup and operations, and the dominant atmospheric and oceanic conditions and introduces the different papers of the special section.

[1] The Special Sensor Microwave Imager (SSM/I) integrated water vapor content (IWVC) estimates in a coastal region during nonstationary cold-air outbreak conditions are analyzed using IWVC retrievals obtained from shipborne microwave radiometry (DRAKKAR), water vapor differential absorption laser remote sensing (LEANDRE 2), radiosonde measurements, and numerical weather prediction (NWP) model ALADIN of Meteo-France. The study focuses on the 24 March 1998 Tramontane/Mistral event, which occurred over the Gulf of Lion (GoL) (western Mediterranean) in the framework of the flux, etat de mer et teledetection en condition de fetch variable (FETCH) experiment. Comparisons of SSM/I and ALADIN IWVCs with collocated shipborne microwave radiometry, at distances from the coast between 50 and 100 km, were carried out on a full diurnal cycle. In the morning, when moister conditions prevailed, the agreement between SSM/I (one passage) and DRAKKAR was good while the bias observed in the afternoon (three passages) was larger (i.e., 2 kg m(2)). Reasons for this are investigated. We show that this is due to the fact that the sensitivity limit of the algorithm has been reached during very dry Mistral conditions. This bias is not explained by effects of land contamination, which is shown to remain below 0.2 kg m(-2). No systematic bias was observed between ALADIN and DRAKKAR. Nevertheless, the trend observed on the DRAKKAR data between 1430 and 2030 UT was best captured by SSM/I despite the sensitivity issue. SSM/I and ALADIN IWVC estimates were also found to be in good agreement with collocated airborne lidar measurements, thereby reproducing the spatial evolution of the IWVC with the distance to the coast.

The time course of the unfolding characteristics of the protein moiety and of the thermotropic behavior of the core-located apolar lipids of highly homogeneous low-density lipoprotein (LDL) subspecies (d 1.030-1.040 g/mL) have been evaluated during transition metal- and azo radical-induced oxidation using differential scanning calorimetry. Apolipoprotein B100 (apo-B100) structure was highly sensitive to oxidative modification; indeed, a significant loss of thermal stability was observed at initial stages irrespective of whether oxidation was mediated by site-specific binding of copper ions or by free radicals generated during decomposition of azo compounds. Subsequently, thermal protein integrity was destroyed, as a result of potentially irreversible protein unfolding, cross-linking reactions, and aggregation. Our results suggest that even minimal oxidative modification of apo-B100 has a major impact on the stability of this large monomeric protein. By contrast, the core lipids, which consist primarily of cholesteryl esters and triglycerides and play a determinant role in the thermal transition occurring near physiological temperature, preserved features of an ordered arrangement even during propagation of lipid peroxidation.