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The Ma&iuml, do high-altitude observatory located in Reunion Island (21 ∘ S, 55.5 ∘ E) is equipped with the Lidar1200, an innovative Raman lidar designed to measure the water vapor mixing ratio in the troposphere and the lower stratosphere, to perform long-term survey and processes studies in the vicinity of the tropopause. The calibration methodology is based on a GNSS (Global Navigation Satellite System) IWV (Integrated Water Vapor) dataset. The lidar water vapor measurements from November 2013 to October 2015 have been calibrated according to this methodology and used to evaluate the performance of the lidar. The 2-year operation shows that the calibration uncertainty using the GNSS technique is in good agreement with the calibration derived using radiosondes. During the MORGANE (Ma&iuml, do ObservatoRy Gaz and Aerosols NDACC Experiment) campaign (Reunion Island, May 2015), CFH (Cryogenic Frost point Hygrometer) radiosonde and Raman lidar profiles are compared and show good agreement up to 22 km asl, no significant biases are detected and mean differences are smaller than 9% up to 22 km asl.

International audience

After 43 years of inactivity, the Calbuco volcano, which is located in the southern part of Chile, erupted on 22 April 2015. The space-time evolutions (distribution and transport) of its aerosol plume are investigated by combining satellite (CALIOP, IASI, OMPS), in situ aerosol counting (LOAC OPC) and lidar observations, and the MIMOSA advection model. The Calbuco aerosol plume reached the Indian Ocean 1 week after the eruption. Over the Reunion Island site (21 S, 55.5 E), the aerosol signal was unambiguously enhanced in comparison with "background" conditions, with a volcanic aerosol layer extending from 18 to 21 km during the May-July period. All the data reveal an increase by a factor of 2 in the SAOD (stratospheric aerosol optical depth) with respect to values observed before the eruption. The aerosol mass e-folding time is approximately 90 days, which is rather close to the value (80 days) reported for the Sarychev eruption. Microphysical measurements obtained before, during, and after the eruption reflecting the impact of the Calbuco eruption on the lower stratospheric aerosol content have been analyzed over the Reunion Island site. During the passage of the plume, the volcanic aerosol was characterized by an effective radius of 0.160.02 μm with a unimodal size distribution for particles above 0.2 μm in diameter. Particle concentrations for sizes larger than 1 μm are too low to be properly detected by the LOAC OPC. The aerosol number concentration was 20 times higher that observed before and 1 year after the eruption. According to OMPS and lidar observations, a tendency toward conditions before the eruption was observed by April 2016. The volcanic aerosol plume is advected eastward in the Southern Hemisphere and its latitudinal extent is clearly bounded by the subtropical barrier and the polar vortex. The transient behavior of the aerosol layers observed above Reunion Island between May and July 2015 reflects an inhomogeneous spatio-temporal distribution of the plume, which is controlled by the localization of these dynamical barriers., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; L'histoire de l'Europe dans la Grande Guerre reste à écrire dans sa dimension policière, en dépit de la fréquente invocation de la « contrainte » dans l'historiographie du conflit. Césure par excellence entre XIXè et XXè siècle, la Première Guerre mondiale fait plus que séparer deux périodes ; c'est une profonde vacance historiographique, au niveau national comme européen. À l'échelle de l'Europe, tandis que l'approche comparative et féconde menée par Jonas Campion, confrontant les cas des gendarmeries belge, française et néerlandaise porte sur la sortie de la Seconde Guerre mondiale , le volume dirigé par G. H. Blaney s'intéresse à l'entre-deux-guerres ; portant notamment sur le premier conflit mondial, l'étude récente des justices militaires , quoique essentielle, ne constitue qu'un élément d'un ensemble bien plus large, de même que l'important recueil sur le crime et la violence à l'époque contemporaine . Dans l'histoire française des gendarmeries, les ouvrages se concentrant sur le XIXè siècle s'arrêtent souvent en 1914, quand la grande majorité des travaux sur le XXè siècle s'intéresse surtout à la Seconde Guerre mondiale, et ce n'est que très récemment que des travaux pionniers, ceux d'Olivier Buchbinder sur la gendarmerie prévôtale , de Soazig Delebecque sur la Garde républicaine , de Cécile Blanchemanche sur la gendarmerie en Algérie , d'Isabelle Roy sur l'expédition de Macédoine , et surtout l'étude d'ensemble de Louis-Napoléon Panel , se sont intéressés à cette césure pour elle-même, comme à une période brève mais intense et foncièrement différente de celle qui l'a précédée autant que de celle qui l'a suivie. En dépit de leur apport substantiel, ces recherches ne peuvent épuiser une thématique si riche et complexe, d'autant moins qu'elles ne s'insèrent pas dans le cadre plus général de la pluralité des polices dont l’action conjointe demeure encore rarement envisagée . L'histoire comparée de l'ensemble des polices dans la Première Guerre mondiale reste donc à écrire. De même que l’économie de paix se mue en système productif de guerre, les forces de l’ordre dans leur ensemble doivent s’adapter à de nouvelles conditions, comme le manifeste de façon emblématique Jules Sébille : chef des brigades mobiles avant 1914, il est attaché au généralissime Joffre pendant le conflit puis devient directeur des services généraux de police d’Alsace et de Lorraine pour les réorganiser et les franciser après la victoire. La démarche comparative s'impose non seulement parce que la Première Guerre mondiale a imposé des conditions d'activité comparables aux pays européens belligérants et dans une certaine mesure, aussi aux neutres, mais également parce que les similarités entre leurs systèmes policiers étaient grandes, en raison de la circulation et de l’adaptation du modèle français de gendarmerie, qui se retrouve notamment en Allemagne, en Belgique ou en Italie, mais également du fait que les forces de police tendent à s’observer, s’hybrider et s’influencer les unes les autres par le biais de « circulations policières » récemment étudiées sous la direction de Catherine Denys . L'approche comparée, large, dans une perspective européenne, destinée à établir des caractéristiques transnationales, ne peut atteindre sa fin qu'en restant soucieuse des singularités, qui existent entre plusieurs pays (ainsi, alors que les prévôtaux sont issus de la gendarmerie en France, en Belgique et en Allemagne, ils constituent une force autonome au Royaume-Uni, celle de la Royal Military Police), mais également en un même État, par exemple au sein même de la gendarmerie française, entre gendarmeries départementale, prévôtale, maritime, Garde républicaine, dont les corps et les conditions d'emploi au sein de la guerre diffèrent. En outre, l'examen des polices et des gendarmeries européennes ne doit pas limiter le regard à la seule Europe : le conflit est mondial, comme le sont certaines puissances belligérantes, dotées d'empires coloniaux, sur lesquels le conflit retentit d'une manière ou d'une autre – cette incorporation de l'espace colonial est d'autant plus intéressante qu'elle correspond à l'essor des études sur les polices coloniales dans les historiographies européennes dont Sven Schepp témoigne pour la partie allemande avec la police territoriale en Afrique allemande du Sud-Ouest . Enfin, à ce cadre géographique large, destiné à prendre toute la dimension du conflit, correspond un cadre temporel de même ambition : on s'intéressera non seulement aux polices et aux gendarmeries lors du conflit lui-même, mais on inclura également sa préparation et surtout ses suites, car la Grande Guerre ne s'est pas arrêtée brutalement en 1918 avec l'armistice : il importe donc d'étudier non seulement la mémoire de l'action des polices et des gendarmeries dans le conflit, mais également de les voir face aux démobilisations, à l'éventuelle hausse de la violence , aux transformations sociales et politiques, au redécoupage des frontières, aux mouvements de protestation ou de révolution de l'immédiat après-guerre, à l'application du traité de Versailles en Allemagne comme au Levant ou dans les colonies, aux opérations militaires illégales comme à Fiume ou à Memel. Ce colloque veut ouvrir de nouvelles perspectives plutôt que d'apporter des réponses complètes et définitives sur un champ historiographique particulièrement vaste, complexe, nouveau. Parmi les axes de réflexion sur ce thème, on pourra se demander : en quoi la guerre changea-t-elle l’organisation, l'activité et les priorités policières ? Quelle fut la part prise par les policiers et les gendarmes européens ex officio, comme les carabiniers italiens , ou individuellement, comme de nombreux gendarmes français, aux combats de la Première Guerre mondiale ? Quelle part polices et gendarmeries prirent-elles aux désordres, aux contestations (ainsi de la grève de la police au Royaume-Uni ) ou aux crimes de la période (participation au génocide arménien ) ? Dans quelle mesure gendarmes et policiers furent-ils plus militarisés à la fin du conflit, comme le suggère l'exemple des carabiniers italiens ? Jusqu'à quel point la guerre, par les contacts entre alliés ou entre occupants et occupés, favorisa-t-elle les circulations policières ? En quoi la guerre fut-elle un accélérateur des tendances à l'œuvre avant-guerre, ou, au contraire, les contraria-t-elle ?

International audience; « La guerre en somme c’était tout ce qu’on ne comprenait pas. Ça ne pouvait pas continuer » , comme s’en effare le héros célinien, Ferdinand Bardamu. En ce centenaire de la Première Guerre mondiale, il convient précisément de mieux comprendre le conflit par un de ses aspects qui ne pouvait continuer d’être largement ignoré dans son Histoire. Il s'agit de la part prise par les agents de l'ordre (policiers et les gendarmes, dans la diversité de leurs statuts et situations) dans les sociétés en guerre, ce théâtre de violence paroxystique qui, de prime abord, laisse penser que les force de l’ordre du temps de paix n’ont (plus) aucun rôle à y jouer. Les potentialités de cette problématique sont plurielles. Un tel champ de recherches donne en effet à voir par le biais de l'évolution des systèmes, des pratiques et des acteurs de la régulation policière – les titulaires légitimes du monopole de la violence étatique pour reprendre la définition wéberienne classique – les tranformations conjointes des sociétés, de leur rapport à la violence mais également de leurs déviances, face aux pressions induites par le conflit sur les communautés locales ou nationales.

International audience; After 43 years of inactivity, the Calbuco volcano which is located in the southern part of Chile erupted on 22 April 2015. The space-time evolutions (distribution and transport) of its aerosol plume are investigated by combining satellite (CALIOP, IASI, OMPS), in situ aerosol counting (LOAC OPC) and lidar observations, and the MIMOSA advection model. The Calbuco aerosol plume reached the Indian Ocean 1 week after the eruption. Over the Reunion Island site (21° S; 55.5° E), the aerosol signal was unambiguously enhanced in comparison with "background" conditions with a volcanic aerosol layer extending from 18 km to 21 km during the May–July period. All the data reveal an increase by a factor of ~ 2 in the SAOD (Stratospheric Aerosol Optical Depth) with respect to values observed before the eruption. The aerosol e-folding time is approximately 90 days. Microphysical measurements obtained before, during and after the eruption reflecting the impact of the Calbuco eruption on the lower stratospheric aerosol content have been analyzed over Reunion site. During the passage of the plume, the volcanic aerosol was characterized by an effective radius of 0.16 ± 0.02 µm with an unimodal lognormal size distribution and the aerosol number concentration appears 20 times higher than before and one year after the eruption. A tendency toward "background" conditions has been observed about one year after the eruption, by April 2016. The volcanic aerosol plume is advected eastward in the Southern Hemisphere and its latitudinal extent is clearly bounded by the subtropical barrier and the polar vortex. The transient behavior of the aerosol layers observed above Reunion Island between May and July 2015 reflects an inhomogeneous geographical distribution of the plume which is controlled by the latitudinal motion of these dynamical barriers.

In order to recognize the importance of ozone (O3) in the troposphere and lower stratosphere in the tropics, a DIAL (differential absorption lidar) tropospheric O3 lidar system (LIO3TUR) was developed and installed at the Université de la Réunion campus site (close to the sea) on Reunion Island (southern tropics) in 1998. From 1998 to 2010, it acquired 427 O3 profiles from the low to the upper troposphere and has been central to several studies. In 2012, the system was moved up to the new Maïdo Observatory facility (2160-l. - metres above mean sea level) where it started operation in February 2013. The current system (LIO3T) configuration generates a 266 beam obtained with the fourth harmonic of a Nd:YAG laser sent into a Raman cell filled up with deuterium (using helium as buffer gas), generating the 289 and 316 beams to enable the use of the DIAL method for O3 profile measurements. The optimal range for the actual system is 6-19ga.m.s.l. depending on the instrumental and atmospheric conditions. For a 1gh integration time, vertical resolution varies from 0.7gkm at 6ga.m.s.l. to 1.3gkm at 19ga.m.s.l. and mean uncertainty within the 6-19gkm range is between 6 and 13g%. Comparisons with eight electrochemical concentration cell (ECC) sondes simultaneously launched from the Maïdo Observatory show good agreement between data sets with a 6.8g% mean absolute relative difference (D) between 6 and 17ga.m.s.l. (LIO3T lower than ECC). Comparisons with 37 ECC sondes launched from the nearby Gillot site during the daytime in a ±24gh window around lidar shooting result in a 9.4g% D between 6 and 19ga.m.s.l. (LIO3T lower than ECC). Comparisons with 11 ground-based Network for Detection of Atmospheric Composition Change (NDACC) Fourier transform infrared (FTIR) spectrometer measurements acquired during the daytime in a ±24gh window around lidar shooting show good agreement between data sets with a D of 11.8g% for the 8.5-16gkm partial column (LIO3T higher than FTIR), and comparisons with 39 simultaneous Infrared Atmospheric Sounding Interferometer (IASI) observations over Reunion Island show good agreement between data sets with a D of 11.3g% for the 6-16gkm partial column (LIO3T higher than IASI). ECC, LIO3TUR and LIO3T O3 monthly climatologies all exhibit the same range of values and patterns. In particular, the Southern Hemisphere biomass burning seasonal enhancement and the ozonopause altitude decrease in late austral winter-spring, as well as the sign of deep convection bringing boundary layer O3-poor air masses up to the middle-upper troposphere in late austral summer, are clearly visible in all data sets., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; Standardized definitions of vertical resolution and a standardized approach for the definition, propagation and reporting of uncertainty in the ozone lidar profiles contributing to the Network for the Detection for Atmospheric Composition Change (NDACC) database were recently developed.Two standardized definitions that describe homogeneously and unequivocally the impact of vertical filtering were recommended. The first definition is based on the width of the response to a Finite Impulse-type perturbation. The second definition relates to the cut-off frequency of a digital filter. Both definitions yield approximately the same values. Numerical tools (routines written in several programming languages) were developed and distributed to lidar investigators in order to implement these standardized definitions within the entire network NDACC, as well as across the tropospheric ozone network TOLNet.The proposed approach for the introduction and propagation of uncertainty in the NDACC ozone DIAL algorithms relies on the careful selection of independent uncertainty components propagated in parallel through the data processing chain before being combined together into an ozone combined standard uncertainty. The uncertainty sources contributing to the uncertainty budget include detection noise, saturation correction, background noise extraction, the absorption cross-sections of ozone, NO2, SO2, and O2, the molecular extinction cross-sections, and the number densities of the air, NO2, and SO2.The network-wide implementation of the proposed standardized definitions and approaches now allows a clear interpretation of the effective vertical resolution of lidar profiles when compared to profiles measured by other instruments/techniques, and allows a clear understanding and interpretation of the quality and limitations of the lidar measurements within NDACC and TOLNet. A review of these definitions and approaches and the implication for future data intercomparisons will be presented at the Symposium.

International audience; Raman water vapor Lidar start to investigated 20 years ago on existing lidars in the frame of the NDACC network located in South of France (44°N, 6°E) and in Reunion Island (21°S, 55°E) with elasting scatter to register simultaneously cristal particules. From this experiment, a nex system have been designed to monitor the water vapor in the whole troposphere up to the lower stratosphere. Measurements have been validated with CFH and Vaisala radiosondes. Measuring quantities of a few ppmv in the lower stratosphere is achiveded. Calibration methodology have been developped and tested during the campaign MALICCA (MAïdo LIdar Calibration CAmpaign). The lidar water vapor profiles are calibrated with water vapor columns obtained from a collocated GNSS receiver. New methodologies of data averaging have been developped, for a long-term monitoring and studies of water transport around the tropopause. Few cases studies are presented to illustrated lidar capabilities.

International audience; Observatories of the climate system are essential to assess future climate predictions that are central and fundamental requirements for determining future mitigation strategies. such observing platforms are very few ones in the tropical southern hemisphere. Cnrs, Université de la réunion, région réunion and the european FeDer program support together the construction of a high- altitude observatory which is operational since October 2012 in La Réunion (South West Indian Ocean, 2160 m asl, latitude 21°S, longitude 55°E). The Maïdo observatory takes over from its predecessor programs at sea level over the island who started long-term observation data of atmospheric chemical composition since 1994. the Maïdo observatory is an ideal platform to sample the atmosphere with different techniques (in-situ analysers, radiosounding, passive and active remote sensing) and to record surface measurements and vertical profiles from ground to the mesosphere over a subtropical latitude band poorly sampled by other international programs. The Maïdo observatory hosts lidars, one UV spectrometer, one radiosonding station, Ftir spectrometers, microwave radiometers, one lightning antenna, cameras, one Gnss station, microbarometers, etc. these devices sample many atmospheric parameters (e.g., meteorological parameters, reactive and greenhouse gases, aerosols, lightning and transient luminous events, infrasounds, etc). part of this very extensive range of instruments is approved and belongs to international networks like nDaCC (network for the Detection of atmospheric Composition Change), sHaDOZ (southern Hemisphere aDditional OZonesondes), tCCOn (total Carbon Column Observing network), and WWLLN (World Wide Lightning Location Network). in-situ analysers regroup measurements of reactive and greenhouse gases, and aerosols measurements approved by or applying to networks like GAW/WMO (Global Atmospheric Watching / World Meteorological Organization), iCOs (integrated Carbon Observing system). The Maïdo observatory is currently the only way to provide regular remote and in-situ atmospheric observations at subtropical latitudes and at high resolutions (seconds in time, few tenths of meters vertically) over a marine-remote region poorly sampled by other programs. it provides data for users in science and policy including air quality forecasting, verification of CO2 emissions and Kyoto monitoring, numerical weather prediction, and validation of global chemical transport model, global climate chemical model and satellite products. since its participation in on-going european projects (nOrs, aCtris-2, arise-2), and thanks to the start of delivery of data in near real time, the Maïdo observatory will largely contribute to the Copernicus atmosphere Monitoring services (CaMs). the Maïdo observatory is open to transnational access thanks to its participation in european programmes like aCtris-2 and enVriplus. this presentation will give an overview of results achieved so far and a number of highlights to illustrate the promise Maïdo observatory data hold for the future, allowing new applications and analysis for a broad community of users.

International audience; We present a Rayleigh-Mie-Raman LIDAR system in operation at Clermont-Ferrand (France) since 2008. The system provides continuous vertical tropospheric profiles of aerosols, cirrus optical properties and water vapour mixing ratio. Located in proximity to the high altitude Puy de Dôme station, labelled as the GAW global station PUY since August 2014, it is a useful tool to describe the boundary layer dynamics and hence interpret in situ measurements. This LIDAR has been upgraded with specific hardware/software developments and laboratory calibrations in order to improve the quality of the profiles, calibrate the depolarization ratio, and increase the automation of OPEN ACCESS Sensors 2015, 15 3042 operation. As a result, we provide a climatological water vapour profile analysis for the 2009–2013 period, showing an annual cycle with a winter minimum and a summer maximum, consistent with in-situ observations at the PUY station. An overview of a preliminary climatology of cirrus clouds frequency shows that in 2014, more than 30% of days present cirrus events. Finally, the backscatter coefficient profile observed on 27 September 2014 shows the capacity of the system to detect cirrus clouds at 13 km altitude, in presence of aerosols below the 5 km altitude.

The international Network for the Detection of Atmospheric Composition Change (NDACC) is a global network of high-quality, remote-sensing research stations for observing and understanding the physical and chemical state of the Earth atmosphere. As part of NDACC, over 20 ground-based lidar instruments are dedicated to the long-term monitoring of atmospheric composition and to the validation of space-borne measurements of the atmosphere from environmental satellites such as Aura and ENVISAT. One caveat of large networks such as NDACC is the difficulty to archive measurement and analysis information consistently from one research group (or instrument) to another. Yet the need for consistent definitions has strengthened as datasets of various origin (e.g., satellite and ground-based) are increasingly used for inter- comparisons, validation, and ingested together in global assimilation systems. In the framework of the 2010 Call for Proposals by the International Space Science Institute (ISSI) located in Bern, Switzerland, a Team of lidar experts was created to address existing issues in three critical aspects of the NDACC lidar ozone and temperature data retrievals: signal filtering and the vertical filtering of the retrieved profiles, the quantification and propagation of the uncertainties, and the consistent definition and reporting of filtering and uncertainties in the NDACC-archived products. Additional experts from the satellite and global data standards communities complement the team to help address issues specific to the latter aspect.