Dissertations / Theses on the topic 'Europe (satellite)'

This thesis concerns development of a communication strategy in Eastern Europe, particularly Bulgaria, as a model country, in the area of international tolling, more precisely road user charging system offered by Satellic. In this strategy the promotion mix tools such as advertising, personal selling, PR, public affairs, events and conferences are applied. A concrete target group, the key message, the goal, the message strategy and the budget are created in each of the above noted promotion mix tools.

Les nuages sont une composante majeure du système Terre-océan-atmosphère car ils couvrent en moyenne 40% de la surface du globe. Ils contribuent à refroidir la troposphère car ils réfléchissent une part importante du rayonnement solaire (effet d’albédo), mais ils contribuent également à la réchauffer car ils réémettent une partie du rayonnement infrarouge terrestre (effet de serre naturel). La détermination des effets radiatifs des nuages a été identifiée par le GIEC comme l’une des sources principales d’incertitude sur la prévision du climat. Dans ce contexte, la question se pose quant au rôle de la variabilité décennale de ces propriétés nuageuses. Plus particulièrement, on cherche à identifier une possible évolution ou variation des propriétés des nuages et à comprendre l'impact de cette variabilité sur celle du climat régional (température au sol), et inversement : ici, la région d'étude est l'Europe. On sait en effet qu'au 1er ordre le climat régional européen est contrôlé par la circulation atmosphérique de grande échelle (Cattiaux et al., ou Cassou et al., 2005) mais celle-ci ne suffit pas à expliquer certaines anomalies ou extrêmes de température. Des anomalies de propriétés nuageuses sont donc une piste importante à étudier pour expliquer ce type d’événement extrême. Durant cette thèse, nous proposons donc d'appréhender cette question à partir d'observations spatiales et de simulations. Les observations seront celles de l'Aqua-Train : (1) l'instrument MODIS à bord du satellite Aqua permet, à l'aide d'algorithmes développés à la Nasa, de caractériser le forçage radiatif des nuages depuis 9 ans (i.e. leur capacité à refroidir ou à réchauffer); (2) le lidar du satellite CALIPSO couplé au radar du satellite CloudSat nous renseigne sur la structure verticale de ces mêmes couches nuageuses, leurs propriétés précipitantes et microphysiques depuis 7 ans. Les simulations utilisées pour compléter ces observations sont déjà existantes : elles ont été réalisées avec le modèle régional WRF et couvrent l'ensemble de l'Europe sur une période suffisamment longue pour pouvoir travailler sur la variabilité interannuelle à décennale des nuages. L’objet de la thèse est d'analyser à l'échelle régionale les relations entre les anomalies nuageuses et les anomalies de température. On cherchera à comprendre si les propriétés des nuages sont perturbées pour un régime synoptique donné et si ces perturbations peuvent expliquer certaines anomalies de température via leur effet radiatif direct ou plus indirect dans le cas des nuages convectifs. La démarche suivante sera appliquée : (1) Les observations et les simulations seront analysées conjointement pour mieux caractériser les propriétés nuageuses et surtout leur variabilité spatiale et interannuelle. (2) Ce travail de caractérisation des propriétés nuageuses devra se faire pour chaque régime synoptique identifié. Les saisons d'hiver et d'été seront caractérisées grâce aux régimes de l'Oscillation Nord Atlantique (NAO) (en collaboration avec le LSCE), tandis qu'un travail sur les régimes des saisons intermédiaires sera nécessaire. (3) Nous chercherons ensuite à comprendre comment ces propriétés typiques d’un régime sont perturbées. A régime fixé, nous tenterons de relier des anomalies de couverture nuageuse à des anomalies de température, et les périodes identifiées seront étudiées en détail pour comprendre quels sont les mécanismes qui permettent de passer d’une anomalie de l’un à une anomalie de l’autre : en d’autres termes, il s’agira d’estimer si le forçage radiatif de ces « anomalies nuageuses » peut conduire à l’anomalie de température détectée. Les comparaisons entre simulations et observations seront utiles pour analyser ces liens (existent dans les 2, ou uniquement dans l'un et pourquoi). Le travail de thèse pourra alors consister à réaliser de nouvelles simulations afin de mieux comprendre ces relations<br>We characterize the seasonal and inter-annual variabilities of the clouds fraction profiles in both observations and simulation since they are critical to better assess the impact of clouds on climate variability. The spaceborne lidar onboard CALIPSO, providing cloud vertical profiles since 2006, is used together with a 23-year WRF simulation at 20 km resolution. A lidar simulator helps to compare consistently model with observations. The bias in observations due to the satellite under-sampling is first estimated. Then we examine the vertical variability of both occurrence and properties of clouds. It results that observations indicate a similar occurrence of low and high clouds over continent, and more high than low clouds over the sea except in summer. The simulation shows an overestimate (underestimate) of high (low) clouds comparing to observations, especially in summer. However the seasonal variability of the cloud vertical profiles is well captured by WRF. Concerning inter-annual variability, observations show that in winter, it is twice more important for high clouds than for low clouds, which is well simulated. In summer, the observed inter-annual variability is vertically more homogeneous while the model still simulates more variability for high clouds than for low clouds. The good behavior of the simulation in winter allows us to use the 23 years of simulation and 8 years of observations to estimate the time period required to characterize the natural variability of the cloud fraction profile in winter, i.e the time period required to detect significant anomalies and trends

Governments have funded the development and production of advanced technology in order to establish supply security and/or to achieve economic growth. The policy of government funding includes three alternatives: the two basic options of maintaining a national project or participating in international collaboration involving a number of sovereign states, and the third option of doing both in parallel. The study examines international collaboration in such a way as to assist in the selection of the appropriate policy option. Particular attention is paid to the perspective of small and large, advanced and less advanced European countries. The research problem is addressed by focusing exclusively on those results which distinguish international collaboration from a national project, summarised under the concepts of collaborative sharing and collaborative efficiency. The former identifies the sharing of funding and technology not to be found in a national project. The latter identifies the difference in efficiency between international collaboration and a national project. Efficiency, indicated by cost, quality and time, is examined under the headings of policy-making, executive management, industrial rationalisation and production volume. Furthermore, collaborative sharing and efficiency are examined in the context of parallel national projects. This focus on the differences between the policy options provides the basis for selecting the appropriate one. Previous studies fail to give convincing answers to the research problem: they concentrate on collaborative efficiency while neglecting collaborative sharing, and they disagree over whether international collaboration or a national project is more efficient. This study attempts to overcome these shortcomings by examining a major case study of international collaboration, namely the European Communication Satellite Programme. The following conclusions are established. To achieve supply security, the collaborative option is considered appropriate for the large, advanced European country, and the parallel option for the large, less advanced countries. To achieve economic growth, the national option is appropriate for the advanced European countries. The smaller, less advanced countries are seen to play only a limited role in government funding of advanced technology.

La majeure partie de mon travail de thèse a porté sur l’étude de la composition chimique de la surface d’Europe. Afin d’apporter une plus-value par rapport aux résultats de l’instrument NIMS à bord de la sonde Galileo qui orbita dans le système jovien de 1995 à 2003, une campagne d’observations depuis le sol a été menée avec le spectromètre imageur infra-rouge SINFONI au VLT. Cinq observations en optique adaptative possédant une résolution spatiale d’environ 160 km et une résolution spectrale R=1500 dans le proche infra-rouge furent acquises. Une procédure complexe de réduction des données a été mise en place afin de construire un cube hyperspectral global en réflectance de la surface. La modélisation linéaire de chacun des spectres du cube a permis d’aboutir aux premières cartes d’abondances absolues jamais obtenues pour la surface d’Europe. Ces cartes confirment la présence des deux espèces majoritaires, la glace d’eau et l’acide sulfurique hydraté. La distribution de l’acide sulfurique est centrée sur l’hémisphère orbital arrière qui est préférentiellement impacté par un flux d’ions de soufre originaires du tore de plasma produit par l’activité volcanique d’Io. Cependant, deux résultats inattendus ont été obtenus. Le premier concerne la glace d’eau, dont la forme cristalline est près de deux fois plus abondante que la forme amorphe selon les résultats de la modélisation. Ce résultat, surprenant compte tenu du taux d’irradiation très élevé auquel la surface est soumise, pourrait s’expliquer par l’existence d’un fort gradient de cristallinité au sein de la couche de glace, mais aussi par l’existence d’une activité endogène relativement soutenue qui se traduit visuellement par une surface peu cratérisée, donc jeune. La corrélation entre la distribution des grains cristallins et la géomorphologie semble accréditer la seconde hypothèse. Le second résultat concerne la détection de sels chlorés à partir de la modélisation des spectres hautement résolus de SINFONI, et non de sulfates, remettant en cause les détections marginales annoncées par les observations de l’instrument NIMS/Galileo. La distribution des sels chlorés, tout comme celle de la glace d’eau cristalline, est corrélée à la géomorphologie, ce qui confirme le rôle important des apports endogènes. Des processus tectoniques et cryovolcaniques mis en évidence récemment pourraient être à l’origine de cette distribution. L’autre versant de ma thèse a été consacré aux caractéristiques physiques des grains cométaires de 67P/C-G. L’instrument COSIMA embarqué sur l’orbiter de la sonde Rosetta a permis la collecte, l'imagerie et l'analyse chimique élémentaire des grains présents dans l’environnement proche de 67P/C-G. Une approche automatisée de la détection des grains à partir des images prises par la caméra « COSISCOPE » a été mise en place et a permis de détecter environ 35000 grains ayant une surface de plus de 100 µm2 entre août 2014 et mai 2016. La résolution de 13.7 µm/pixel a rendu possible la caractérisation en détail de la forme et de la structure des grains, et le nombre important de détections a permis d’obtenir des statistiques robustes concernant la distribution en taille et l’évolution de celle-ci au cours du temps. Deux grandes familles de grains ont été identifiées : les grains compacts, qui ne représentent qu’une faible minorité des grains et qui ont été majoritairement collectés en début de mission, et les agrégats, qui ont une structure très poreuse similaire à celle des IDPs et des micrométéorites collectées en Antarctique. La distribution en taille obtenue suit une loi de puissance intégrale en r-2.66. La comparaison avec des lois obtenues à des échelles différentes par d’autres instruments met en évidence des différences qui peuvent être interprétées par des mécanismes d’éjection dépendant de la taille associés à un biais du processus de collecte en orbite<br>The major part of my work focused on the study of the chemical composition of Europa’s surface. In order to provide additional insights in comparison to the results of the NIMS instrument onboard the Galileo spacecraft that orbited in the Jovian system from 1995 to 2003, a ground-based observations campaign was conducted with the infrared imaging spectrometer SINFONI on the VLT. Several observations using adaptive optics with a spatial resolution of about 160 km and a spectral resolution R = 1500 in the near-infrared were acquired and then combined. A specific data reduction pipeline was developed to build a global hyperspectral cube in surface reflectance. The linear modeling of each spectra of this cube leads to the first global abundance maps ever obtained for the surface of Europa. These maps confirm the presence of the two major species, namely water ice and hydrated sulfuric acid. The distribution of the hydrated sulfuric acid is centered on the trailing orbital hemisphere preferentially affected by a sulfur ion flux coming from the plasma torus produced by Io volcanic activity. Two surprising results were obtained. The first one concerns water ice, which crystalline form is about twice more abundant than the amorphous form according to the modeling results. This result, unexpected given the very high radiation rate on the surface, could be explained by a strong crystallinity gradient through the ice slab. However, it could also point out an endogenous activity possibly strong as first suggested by its poorly well-known cratered surface. The correlation between the crystalline grains distribution and the geomorphology seems in favor to the second hypothesis. The second result is related to the detection of chlorinated salts from the modeling of highly resolved spectra from SINFONI. Sulfates, first reported by several analyses of NIMS observations are marginal in the modeled composition, hence challenging their presence on the surface of Europa. The chloride distribution, as well as the one of the crystalline water ice, is correlated to geomorphology, potentially confirming significant endogenous contributions as the result of tectonic and cryovolcanic processes recently highlighted. The second part of my PhD was dedicated to the physical characteristics of the 67P/C-G’s cometary grains. The COSIMA instrument onboard the Rosetta orbiter allowed the collection, imaging and elemental chemical analysis of grains present in the immediate environment of 67P/C-G. An automated approach of the grains detection based on images taken by the camera "COSISCOPE" was set up and able to detect about 35.000 grains having an area of more than 100 µm² between August 2014 and May 2016. The resolution of 13.7 µm/pixel allowed to perform a detailed characterization of the shape and the structure of the grains, and the large number of detections permitted to obtain significant statistics on the size distribution and its evolution over the time. Two large families of grains have been identified: the compact grains, which represent only a small minority of grains mostly collected at the beginning of the mission, and aggregates, which have a very porous structure similar to those of IDPs and micrometeorites collected in Antarctica. The size distribution obtained follows an integrated power law in r-2.66. The comparison with the laws obtained at different scales by other instruments highlights differences that can be interpreted by ejection mechanisms depending on the size associated with a selection bias during the collection process in orbit

Europe est un corps silicaté enveloppé d'une couche d'H2O de 80 à 140 km d'épaisseur formant en surface une croûte de glace I. La dissipation de chaleur générée par l'effet des marées du système jovien maintiendrait un océan liquide sous la croûte de glace et permettrait une dynamique interne. L'analyse morphologique menée sur diverses structures « géologiques » imagées par Galileo apporte des informations sur la structure, l'état thermique et les vitesses de déformation de la croûte. La profondeur des transitions rhéologiques est très variable selon la localité et le type de structure, et donc selon le processus géologique impliqué. La lente relaxation de 2 bassins d'impact permet d'estimer des flux de chaleur inférieurs à 30 mW.m-2 impliquant une croûte conductive de 9 à 32 km d'épaisseur reposant sur un océan froid. Néanmoins, d'autres structures montrent des indices d'écoulements à la faveur d'une pente régionale et de déformations verticales à grande échelle (~100 km) peu fréquentes à la surface d'Europe. En outre, nous avons mis en évidence une disparition importante de croûte autour d'une bande décro-extensive dont l'ouverture serait liée à la rotation non synchrone d'Europe. Ces résultats pourront servir à contraindre les modèles physiques développés par ailleurs.

Europe, l'un des quatre satellites galiléens de Jupiter, fait l'objet d'une attention particulière de la communauté scientifique car il est susceptible d'abriter des conditions d'habitabilité favorables. La présence d'un océan d'eau liquide salée en sous-surface a été mise en évidence par l'analyse des observations de la sonde Galileo, combinée à des simulations numériques. Par ailleurs, des observations du télescope spatial Hubble et la réanalyse de données de la sonde Galileo, comparées à des simulations numériques ont renforcé l'hypothèse de la présence de panaches de vapeur d'eau. Traverser ces dernières pourrait permettre de comprendre la composition de l'océan sous-terrain.L'exploration des lunes galiléennes constitue l'un des principaux objectifs de la mission JUICE (JUpiter ICy moons Explorer) de l'ESA. En préparation des futures observations, un effort de modélisation a été entrepris pour caractériser le système magnétosphère de Jupiter-Europe. Pour caractériser l'interaction entre le plasma jovien, le champ magnétique et l'atmosphère d'Europe, j'ai utilisé le modèle LatHyS (LATMOS Hybrid Simulation). LatHyS est un modèle de simulation hybride 3D, multi-espèces et parallèle qui combine une description cinétique des ions avec une description fluide des électrons. Ce modèle de simulation nous permet de représenter la dynamique et la structure de l'environnement ionisé dans lequel baigne la lune.Mon travail a consisté à développer l'environnement d'Europe au sein de LatHyS. L'atmosphère et l'ionosphère en ont notamment été un aspect central. Les modèles d'interactions Europe-plasma jovien décrivent l'atmosphère de manière empirique et avec un modèle analytique. Cependant, j'ai mis en place une description issue d'un modèle d'exosphère planétaire 3D, appelé EGM, pour caractériser l'atmosphère d'Europe. En couplant EGM avec LatHyS, nous pouvons prendre en compte diverses espèces neutres majoritaires, intégrer des asymétries et obtenir une ionosphère plus proche de la réalité. En parallèle, j'ai développé une méthode d'optimisation qui permet de réduire la taille de l'environnement de la simulation, ce qui permet de réduire le temps d'exécution. Par la suite, j'ai réalisé de multiples simulations comparant diverses conditions neutres et ionosphériques (d'empirique à entièrement modélisées) avec des observations de Galileo afin d'étudier la réponse du système lors de ces variations. Puis j'ai analysé la réponse du plasma à un environnement théorique pendant les deux survols prévus d'Europe par JUICE. Pour finir, j'ai travaillé sur un programme qui calcule la propagation d'une onde radio dans un environnement magnétique. C'est un travail préliminaire qui a pour but d'intégrer l'environnement simulé par le modèle LatHyS dans ce code de tracé de rayon afin d'étudier la propagation des ondes radio émises par Jupiter lors d'une occultation observée par la sonde JUICE<br>Europe, one of Jupiter's four Galilean moons, is subject of recent interest from the scientific community due to its potential to host favorable habitable conditions. The presence of a subsurface salty liquid water ocean has been confirmed through the analysis of Galileo probe observations, combined with numerical simulations. Additionally, observations from the Hubble Space Telescope and a reanalysis of Galileo probe data, compared to numerical simulations, have strengthened the hypothesis of the existence of water vapor plumes. Passing through these plumes could provide insights into the composition of the underground ocean.Exploring the Galilean moons is one of the primary objectives of the ESA's JUpiter ICy moons Explorer (JUICE) mission. In preparation for future observations, modeling efforts have been undertaken to characterize the system jovian magnetosphere-Europa. To characterize the interaction between the jovian plasma, the magnetic field, and Europa's atmosphere, I used the LatHyS (LATMOS Hybrid Simulation) model. LatHyS is a 3D, multi-species, parallel hybrid simulation model that combines a kinetic description of ions with a fluid description of electrons. This simulation model allows us to represent the dynamics and structure of the ionized environment surrounding the moon.My work focused on developing Europa's environment within LatHyS, with a particular emphasis on the atmosphere and ionosphere. Models of the interaction between Europa and Jupiter's plasma traditionally describe the atmosphere empirically and with an analytical model. However, I implemented a description based on a 3D planetary exosphere model called EGM to characterize Europa's atmosphere. By coupling EGM with LatHyS, we can account for various major neutral species, incorporate asymmetries, and obtain an ionosphere that is closer to reality. In parallel, I developed a simulation optimization method to reduce the size of the simulation environment, which reduces runtime. Subsequently, I conducted multiple simulations comparing various neutral and ionospheric conditions (from empirical to fully modeled) with Galileo observations to study the system's response to these variations. I also analyzed the plasma's response to a theoretical environment during the two planned flybys of Europa by JUICE. Finally, I worked on a program that calculates the propagation of a radio wave in a magnetic environment. This preliminary work aims to integrate the environment simulated by the LatHyS model into this ray tracing code to study the propagation of radio waves emitted by Jupiter during an occultation observed by JUICE

Cette thèse a pour objet les chaînes de télévision paneuropéennes, celles qui se sont donné pour cible l'ensemble du continent européen. Parmi toutes les télévisions transnationales, celles-ci ont pour particularité de diffuser leurs programmes dans une aire géographique composée de nombreux pays, avec une diversité de langues et de cultures. Pour observer leur développement, il importe de retracer l'historique de la diffusion avec les différents types de satellites, et celui de la réception par les réseaux câblés ou par la réception directe. La révolution du numérique a ensuite multiplié les possibilités de diffusion, et permis la convergence des systèmes, grâce à laquelle les programmes de télévision peuvent être captés sur un ordinateur ou sur un téléphone mobile. De familiale ou collective, la réception des programmes devient progressivement plus individuelle. Quelles sont les stratégies de ces chaînes paneuropéennes et quels sont leurs programmes? Cette étude propose une typologie permettant de définir les différents types de chaînes de télévision, selon trois critères: l'aire de diffusion, le concept de la chaîne, la langue ou les langues de diffusion. Pour illustrer la méthode adoptée, certaines d'entre elles font l'objet d'une approche plus détaillée : MTV, BBC World News, Deutsche Welle, Eurosport, Euronews, Arte, Discovery et Mezzo. L'évolution de ces chaînes révèle plusieurs tendances : le phénomène de globalisation dans l'économie des médias, une volonté d'établir des règles communes en Europe.

The impact of mineral dust upon climate, ecosystems and air quality represents a major scientific and societal issue. The aim goals of the present Ph.D. Thesis are to evaluate the behaviour and to improve the forecasting skills of a regional dust model and to characterize the desert dust content in Northern Africa, Europe and Middle East. An aerosol characterization was performed using long-term series of aerosol optical depth (AOD) from AERONET sun photometers. The results showed that mineral dust was the most important constituent in Northern Africa and Arabia. Small particles were abundant in sites close to urban and industrial areas of Continental and Eastern Europe and Middle East, and important contributions of biomass burning were observed in the sub-Sahel region in winter. Desert dust transport to Southern Europe was observed from spring to autumn and decreasing with latitude with contributions above 40% to the aerosol column load. Dust models are essential to complement dust-related observations, understand the dust processes and predict the impact of dust on air quality. Despite that the BSC-DREAM8b model has reached a level of delivering reliable operational dust forecasts, it is necessary to conduct an extensive evaluation of its behaviour. The BSC-DREAM8b and the original DREAM models and different research model versions were evaluated over Northern Africa, Mediterranean and Middle East using AERONET measurements and seasonal averages from satellite aerosol products. The model evaluation highlighted that BSC-DREAM8b and DREAM strongly underestimated the dust fields in the Sahel during winter and overestimated dust concentrations during spring rainy events in the Mediterranean. The introduction of new dry deposition scheme and an updates in the wet deposition scheme improved the long-range transport, although significant underestimation remained in the Sahel in winter. The inclusion of a preferential source mask improved the localization of the main North African sources and the long-range dust transport to Europe and Atlantic regions. The inclusion of a more physically-based dust emission scheme with a new soil texture database led to reasonably good results at source areas and subsequent long-range transport. In this case, the use of a preferential source mask didn¿t introduce significant improvements. The long-range dust transport over Europe was evaluated and analysed with an annual simulation of the CALIOPE air quality modelling system. CALIOPE includes CMAQ which calculates biogenic, anthropogenic and sea salt aerosol; and BSC-DREAM8b which provides desert dust. For the evaluation, we used daily PM10, PM2.5 and aerosol components from the EMEP/CREATE network; total, coarse and fine AOD from AERONET and seasonal averages from satellite aerosol products. Overall CALIOPE could reproduce reasonably well the daily variability of the main components and the seasonal aerosol patterns in Europe. However, the PM and AOD levels were underestimated. The most underestimated aerosol components were carbonaceous matter and secondary inorganic aerosols (SIA). A simple model bias correction based on the chemical composition observations was applied to the model simulation to provide an estimation of the spatial and seasonal distribution of aerosols over Europe. The simulated aerosol concentrations presented maximum values over the industrialized and populated areas of the Po Valley and the Benelux regions. SIA were dominant in the fine fractions representing up to 80% of the aerosol budget in latitudes beyond 40ºN. A second maximum was detected over Eastern and Southern Europe. High values in Southern Europe were linked to Saharan dust transport which contributed up to 40% of the total aerosol mass. Maxima dust seasonal concentrations were found between spring and early autumn. These results showed that desert dust is the main responsible of the exceedances of the PM10 EU air quality threshold in large areas south of 45ºN.<br>Una gran quantitat de pols que és mobilitzada en les regions àrides del planeta, és injectada a l’atmosfera sota condicions meteorològiques favorables. A partir de mesures terrestres i de satèl·lit, a més a més d’estimacions obtingudes a partir de models, es calcula que en tot el planeta s’emeten entre centenars i milers de megatones de pols per any. L’impacte que té la pols mineral en el clima, els ecosistemes i la qualitat de l’aire, i per tant, en la salut humana i les activitats econòmiques, representa una qüestió social i científica de gran rellevància. La font més important d’emissió de pols mineral a nivell global és la regió del Sàhara. Els principals objectius de la present tesi doctoral són el d'avaluar el comportament i el de millorar les capacitats de predicció d'un model regional de pols així com el de caracteritzar el contingut de pols desèrtica en el nord d'Àfrica, Orient Mitjà i Europa. En aquest marc de treball, el model regional de pols BSC-DREAM8b i els fotòmetres de la xarxa internacional AERONET són les principals eines que seràn utilitzades en el transcurs de la present investigació. La comparació entre valors observats i simulats no pot ser adequadament entesa si les mesures no estan separades en els seus components fonamentals. Així, es va dur a terme una caracterització d'aerosols per al nord d'Àfrica, Europa i Orient Mitjà. Aquesta caracterització està basada en sèries d'espessor òptic d'aerosols (AOD; Aerosol Optical Depth en anglès) dels fotòmetres de la xarxa AERONET. L'anàlisi d'aquesta base de dades es va realitzar aplicant el mètode de Gobbi i co-autors. Aquest mètode gràfic permet deduir diferents propietats òptiques i físiques dels aerosols (com són el radi efectiu del mode fi i la contribució de les fraccions fines i gruixudes a l’AOD), a més a més, de diferenciar entre diferents processos que fan augmentar el valor de l’AOD com són la humidificació i/o coagulació de les fraccions fines o l'increment de partícules més gruixudes a causa de la presència de núvols. Els resultats van mostrar que la pols mineral és l'aerosol més important al nord d'Àfrica i Aràbia. En estacions properes a zones urbanes i industrials de regions continentals i de l'est d'Europa i Orient Mitjà es van observar partícules fines associades a fonts antropogèniques. També es van detectar importants contribucions en les fraccions fines degudes a la crema de biomassa a la zona del sub-Sahel durant l'hivern. El transport de pols desèrtica cap al sud d'Europa està associat a determinats patrons meteorològics estacionals. Com a resultat, en zones del sud d'Europa, la pols desèrtica es va observar entre primavera i tardor, i la seva contribució (que va arribar superar el 40%) decreixia cap a latituds més al nord. En aquest darrer cas, la pols desèrtica acostumava a trobar-se barrejada amb altres tipus d'aerosols d'origen antropogènic Els models de pols són essencials per complementar les observacions, entendre els processos associats al cicle de la pols i predir el seu impacte en les concentracions en superfície del material particulat (PM; Particulate Matter en anglès). En particular, els models regionals són adequats per a la simulació d'episodis individuals d’instrusió de pols desèrtica. Actualment, el model de pols BSC-DREAM8b és mantingut i desenvolupat en el Barcelona Supercomputing Center – Centre Nacional de Supercomputació (BSC-CNS). En els darrers anys, el model ha proporcionat prediccions diàries de concentracions de pols desèrtica en dos dominis: Nord d'Àfrica-Europa – Europa - Orient Mitjà i Àsia. A pesar que el BSCDREAM8b ha arribat a aconseguir una qualitat de pronòstic operacional capaç de reproduir els episodis d'intrusió saharians més importants que afecten al Mediterrani i Europa, és necessari avaluar el seu comportament en regions font de pols. En aquest context, el model BSC-DREAM8b i la seva versió original, DREAM, així com diferents versions experimentals, van ser avaluats per a un cicle estacional complet utilitzant les dades de la xarxa AERONET i promitjos estacionals de productes d'aerosols de diferents satèl·lits pel Nord d'Àfrica, Orient Mitjà i Europa. Els resultats de l'avaluació del model van mostrar que tant el BSC-DREAM8b com el DREAM subestimaven les concentracions de pols a la regió del Sahel durant l'estació hivernal del Harmattan. Per contra, importants sobreestimacions en l'oest del Mediterrani es van detectar coincidint amb episodis plujosos a la primavera. L’inclusió d'un nou esquema de deposició seca a més de l'actualització de la relació de rentat en l'esquema de deposició humida del model, van aconseguir millores en el transport a llarga distància, en particular sobre el Mediterrani malgrat que les subestimacions a la zona del Sahel van continuar sent persistents a l'hivern. La introducció d'una màscara de fonts preferents basada en la topografia del terreny en l'esquema d'emissió va millorar la localització de les principals regions font en el Nord d'Àfrica. Com a conseqüència, es van observar millores en el transport de llarga distància cap a Europa i les regions Atlàntiques. La inclusió d'un nou esquema d'emissió (que inclou parametritzacions físiques més complexes) a més d'una nova base de dades de textura de sòls va aconseguir bons resultats en regions font així com en regions afectades pel transport de pols a llarga distància. En aquest cas, l’introducció d'una màscara de fonts preferents en l'esquema d'emissió no va mostrar significants millores en comparació dels valors observats. A Europa, es poden trobar diferents tipus d'aerosols associats a diferents fonts d'emissió (tant naturals com antropogèniques) que s’han de tenir en compte quan s'analitzen les contribucions dels aerosols sobre el continent europeu. El transport de pols sahariana cap a sud d'Europa va ser avaluat i analitzat mitjançant una simulació del sistema de modelització de qualitat de l'aire CALIOPE. El sistema de modelització CALIOPE integra un conjunt de models dels quals el BSC-DREAM8b i el model fotoquímic CMAQ proporcionen les estimacions d'aerosols. Per a l'avaluació de CALIOPE es van utilitzar diverses fonts de dades de xarxes en superfície (com la xarxa europea de qualitat de l'aire EMEP/CREATE i la xarxa de AERONET) i mitjanes estacionals de productes d'aerosols de satèl.lits. L'avaluació va mostrar que malgrat subestimar les concentracions d'aerosols, CALIOPE va ser capaç de capturar les variabilitats diàries observades en les estacions en superfície així com reproduir els patrons estacionals observats en els productes de satèl·lit. L'avaluació dels aerosols per components va mostrar que les espècies químiques amb major subestimació pel que fa a les observacions estaven associades a les fraccions fines de carbó elemental i orgànic així com els aerosols secundaris inorgànics (nitrats, sulfats i amoni). Com a resultat, es va aplicar un senzill mètode de correcció de l’error als resultats de la simulació basat en les observacions de la composició química per tal de mostrar una estimació espaial i temporal de la distribució dels diferents aerosols presents a Europa. L'anàlisi de d’aquesta simulació va mostrar que les màximes concentracions d'aerosols es localitzen a les zones poblades i industrialitzades del Benelux i de la Vall del Po. Aquests màxims estan associats a les fraccions fines compostes d'aerosols secundaris inorgànics (observant-se contribucions de més del 80%). Màxims secundaris es van detectar a l'est i sud d'Europa. Les altes concentracions en el sud d'Europa s’associaven al transport de pols sahariana que contribuïa en més d'un 40% al total de la massa en columna. Prop de la superfície, les màximes concentracions estacionals associades al transport de pols (> 30 microg/m3) van ser observades entre primavera i estiu. A més a més, els resultats de la simulació anual d'aerosols per Europa va mostrar que el transport de pols sahariana és el principal responsable de la superació del límit diari de PM10 establert per la Unió Europea (50 microg/m3) en extenses àrees al sud dels 45ºN.

The research activity presented in this manuscript deals with the implementation of a methodology to merge in an optimal way atmospheric modelling and observations at different spatial scales. In particular, we approached the problem of assimilation of ground measurements and satellite columnar data and how the Data Assimilation (DA) could improve the chemical transport model (CTMs) and correct biases and errors in the chemical species forecast. The work focused on tropospheric ozone and the species linked to its formation, since they play a crucial role in chemical processes during photochemical pollution events. The study was carried out implementing and applying an Optimal Interpolation (OI) DA technique in the air quality model BOLCHEM and the CHIMERE CTM. The OI routine was chosen because it has given satisfactory results in air quality modelling and because it is relatively simple and computationally inexpensive. In the first part of the study we evaluated the improvement in the capability of regional model BOLCHEM to reproduce the distribution of tropospheric pollutants, using the assimilation of surface chemical observations. Among the many causes of uncertainties of CTMs simulations, a particular focus is given by uncertainties in emissions, that are known to be high. The scientific purpose was to analyse the efficacy of DA in correcting the biases due to perturbed emission. The work was performed using an Observing System Simulation Experiment (OSSE), which allowed the quantification of assimilation impact, through comparison with a reference state. Different sensitivity tests were carried out in order to identify how assimilation can correct perturbations on O3, induced by NOx emissions biased in flux intensity and time. Tests were performed assimilating different species, varying assimilation time window length and starting hour of assimilation. Emissions were biased quantitatively up to ± 50% and shifted temporally up to ± 2 hours. The analysis brought to the conclusions that NO2 assimilation significantly improves O3 maxima during the assimilation, making it almost independent on different emission scenarios. The assimilation impact lasts up to 36-40 hours after the end of the assimilation window. This is a considerable result, especially when it is taken into account that DA generally yields significantly better forecasts in the 6-12 hours range, but improvements vanish afterwards. The NO2 night-time chemistry has the role of maintaining the correction of O3 due to assimilation also in the following day. Assimilating NO2 and O3 simultaneously bring to rather better results, although the benefit lasts only a few hours after the end of the assimilation window. It was found that the best results are achieved assimilating observations during the photochemically active period (06-18 UTC). It was also found that temporally biased NOx emissions only slightly perturb O3 concentration during the photochemically active regime, while the perturbation is larger during night-time. Assimilation has a very low impact during the assimilation window and a negligible impact after its end. The second part of PhD research activity dealt with the evaluation of the impact of assimilation of satellite NO2 tropospheric columns on the distribution of pollutants at the ground level during photochemical pollution events at continental scale. In particular, we focused on the assimilation of observations from SCIAMACHY and from OMI, and its effect on ozone in the lowermost troposphere in Europe. For an effective improvement in assimilated fields it is particularly important the consistency between satellite and model resolution. SCIAMACHY and OMI have a considerable difference in spatial and temporal resolution, allowing to test the role of data resolution on the effectiveness of assimilation. The role of data resolution on the effectiveness of assimilation was investigated also changing the model resolutions. It was found the perturbation on NO2 field due to assimilation causes a modification on ozone field that appears more spatially variable and higher in some photochemical polluted areas. Similar effects are detected both for SCIAMACHY and OMI assimilation. Significative effects of assimilation on ozone can be appreciate in polluted areas at local scale. Focusing on specific subdomains, it was found that the effect of assimilation lasts, in general, 8 hours and in few cases until the reactivation of active photochemical period in the following day. This is a strong impact, considering that assimilation is performed at most once a day and it is probably linked to the model underestimate of ozone and its precursors in polluted areas with respect to those measured by SCIAMACHY and OMI. In wide and highly polluted areas assimilation achieves satisfactory results, comparing simulated ground ozone with independent ground measurements. In that region where OMI assimilation in the coarse and fine resolution simulations and SCIAMACHY assimilation were confronted, we could conclude that these different assimilation set-up are almost similar. Whereas, in more localised polluted areas (i.e. comparable to model and satellite resolution), OMI assimilation in the finer resolution simulation performs better with respect to OMI assimilation in the coarse resolution simulation and SCIAMACHY assimilation. As a general conclusive statement, assimilation can be an important tool to make the spatial and temporal distribution of pollutants more realistic and closer to the specific local differences with the caveat of horizontal resolution of the assimilated columns and model simulations.

L'insolation est étudiée, à l'échelle synoptique (la France) à l'aide d'un ensemble de mesures de la durée quotidienne d'insolation réalisées au sol et par télédétection satellitaire. L'objectif poursuivi est d'analyser une série de données suffi* samment longue pour caractériser de manière statistique le comportement climatologique de l'insolation dans l'espace. Les données sont fournies par 88 héliographes du réseau synoptique français ainsi que par le programme " Cactus " de la Météorologie Nationale, qui utilise les images visibles du satellite Météosat. L'étude porte sur une année de données. La similarité de la structure spatiale des mesures du sol et du satellite est montrée par analyse objective, et par analyse en composantes principales de processus. La fine perception de la variabilité spatiale du satellite est alors utilisée pour optimiser un réseau de mesures au sol. Les performances du programme Cactus sont comparées avec celles de méthodes d'interpolation classiques (basées sur 23 héliographes), pour l'estimation du rapport d'insolation. Elles se sont révélées plus performantes en terme de cofluctuation. Il apparaît cependant une tendance du satellite à exagérer les valeurs extrêmes. L'étalonnage des mesures satellitaires par des mesures sol a pour but de conjuguer les qualités de précision des hélio* graphes, et la définition spatiale du satellite. Une approche géostatistique est proposée. L'effet recherché est observé à partir d'une certaine densité du réseau d'étalonnage

Nous avons mis en oeuvre une méthode statistique déjà existante (Cano, 1982) d'évaluation du rayonnement global à 1' aide des mesures du satellite Météosat. Cette méthode a été testée sur environ 1800 données : 11 mois de l'année 1983, 11 mois de l'année 1984 et 7 mois de l'année 1985. Les grands points de cette méthode statistique sont les suivants : 1) la construction d'une carte d'albédo planétaire par ciel clair d'après une série temporelle d'images sous conditions ciel clair, 2) l'évaluation d'un indice d'ennuagement, n, représentant le pourcentage du pixel recouvert par les nuages, par comparaison avec la carte d'albédo planétaire (albédo référence), 3) l'évaluation de la relation statistique entre la transmittance atmosphérique horaire (K), définie comme le rapport entre le rayonnement global et le rayonnement hors atmosphère (G0h), et n (l'indice d'ennuagement). Cette relation est du type : K = -a n + b ou Gh / G0h = -a n + b, où a et b > 0. Les coefficients de régression de cette relation ont été établis à partir des données du réseau de la Météorologie Nationale (Gh) et des données quotidiennes du canal visible de Météosat (n). En conclusion, nous pouvons dire que cette méthode est satisfaisante, elle permet 1) d'affiner ou de compléter (océans) les atlas du rayonnement déjà existants, en mettant en évidence des micro-climats (précision à 5 km près) peu connus ou inconnus, 2) l'évaluation du rayonnement global horaire moyen mensuel avec une précision de l'ordre de 0,1 kWh/m2, 3) un grand nombre d'application dites solaires (précision de rentabilité, méthode de conception architecturale assistée par micro-ordinateur, dimensionnement ...).

This thesis provides a new space-time statistical rain model and a novel space-time interpolation approach for planning and dimensioning wide area high frequency satellite communication networks. Key characteristics of rainfall rate fields are modelled. These include detailed description of: (i) the first order statistical distribution, (ii) the spatial and temporal correlation functions of rainfall rate and, and (iii) the probability of rain/no-rain. With a focus on their relevance to satellite and terrestrial microwave network design, the key contribution of this study is the assessment of the impact of varying spatial and temporal integration lengths on these quantities. The issue of how these key characteristics of rainfall rate field change with different area sizes are analysed in this thesis and it is novel. A simple but accurate interpolation approach of the key characteristic parameters is presented in this thesis. The novelty of the proposed technique is that it does not rely directly on the radar/raingauge derived rainfall rate data like traditional models do but rather on fitted coefficients and computed rain characteristics. This thesis proposes rain parameter contour maps and databases covering the whole of Western Europe from which users can conveniently obtain the key rain characteristic parameters at any location within the studied area. More speculatively, the space-time interpolation approach can extrapolate to rain parameters at space-time resolutions shorter than those in the NIMROD databases. The results have been validated by comparing them with those from ITU Rec model and measurements by NIMROD rain radar. In addition, a Graphical User Interface (GUI) software has been provided that allows users to interact with the proposed model. The user can easily obtain the information of the key rain characteristics at different space-time scales by simply inputting the longitude, latitude, space resolution and time resolution of the location of interest. The detailed results are then automatically calculated and displayed by the software significantly facilitating rain rate study.

In 1979, the IRIS infrared spectrometers on the two Voyager spacecraft obtained over 1000 disk-resolved thermal emission spectra of Europa, Ganymede, and Callisto, Jupiter's three large icy satellites. This dissertation describes the first detailed analysis of this data set. Ganymede and Callisto subsolar temperatures are 10°K and 5°K respectively below equilibrium values. Equatorial nighttime temperatures are between 100°K and 75°K, Callisto and Europa being colder than Ganymede. The diurnal temperature profiles can be matched by 2-layer surfaces that are also consistent with the eclipse cooling observed from earth, though previous eclipse models underestimated thermal inertias by about 50%. Substrate thermal inertias in the 2-layer models are a factor of several lower than for solid ice. These are 'cold spots' on Ganymede and Callisto that are not high-albedo regions, which may indicate large thermal inertia anomalies. All spectra show a slope of increasing brightness temperature with decreasing wavelength, indicating local temperature contrasts of 10-50°K. Callisto spectra steepen dramatically towards the terminator, a trend largely matched with a laterally-homogeneous model surface having lunar-like roughness, though some lateral variation in albedo and/or thermal inertia may also be required. Subsolar Ganymede spectra are steeper than those on Callisto, but there is no steepening towards the terminator, indicating a much smoother surface than Callisto's. The spectrum slopes on Ganymede may indicate large lateral variations in albedo and thermal inertia. A surface with similar areal coverage of dark, very low thermal inertia material, and bright material with thermal inertia a factor of 2-3 below solid ice, fits the diurnal and eclipse curves, and (less accurately) the IRIS spectrum slopes. Europa spectra have very small slopes, indicating a smooth and homogeneous surface. Modelling of surface water ice migration gives a possible explanation for the inferred lateral inhomogeneities on Ganymede. Dirty ice surfaces at Jupiter are subject to segregation into high-albedo ice-rich cold spots and ice-free regions covered in lag deposits, on decade timescales. Ion sputtering and micrometeorite bombardment are generally insufficient to prevent the segregation. The reflectance spectra of Ganymede and Callisto may be consistent with this type of segregated surface.

Cette thèse aborde l’histoire des activités spatiales françaises en parcourant leur évolution depuis les premières recherches scientifiques dans la haute atmosphère entreprises après la fin de la deuxième guerre mondiale jusqu’à la création de l’Agence spatiale européenne (ESA), au milieu des années 1970. Née dans la guerre froide, la politique spatiale française constitue sous la présidence du général de Gaulle, un des éléments de la politique d’indépendance nationale puis, sous l’ère du Président Pompidou, elle accentue son caractère industriel ouvert à la coopération avant de devenir européenne au début du septennat du Président Giscard d’Estaing. Centrée sur le Centre national d’études spatiales (CNES) l’étude souligne le rôle de l’État dans un secteur de hautes technologies où la politique est soumise à l’interaction entre des facteurs nationaux et internationaux comportant des enjeux géopolitiques et géostratégiques. Privilégiant les aspects institutionnels, elle analyse le processus d’élaboration de la politique mise en œuvre à partir des années 1960. D’abord, perçue comme élément de prestige au service du rayonnement de la France dans le monde, la politique spatiale interagit avec l’évolution du système technique pour répondre aux enjeux économiques et industriels que comportent les applications spatiales. L’étude met en évidence l’impérieuse nécessité d’un dialogue permanent entre les acteurs, techniciens et politiques, dont l’interdépendance participe à la formation du processus décisionnel<br>The subject of this thesis is the history of space activities in France, evolving from the first scientific atmospheric research programmes undertaken after the Second World War up to the creation of the European Space Agency (ESA) in the 1970s.A by-product of the Cold War, the French Space Policy was one of the pillars of national independence under the presidency of General De Gaulle. Under President Pompidou, it becomes more industrial and opens up to cooperation, only to become European in the beginning of President Giscard d’Estaing 7-year mandate.Focused on the French space agency (Centre national d’etudes spatiales (CNES)), this study emphasizes the role of the state in the high technology sector where policy is submitted to the interaction of national and international factors, taking into account geopolitical and geostrategic stakes. Highlighting the institutional aspects, the study analyses the elaborative process of the policy implemented in the 1960s. First of all perceived as a way of putting France in the spotlight at global level, space policy evolves with technology to face the economic and industrial challenges of space applications. The study highlights the vital necessity of a permanent dialogue between technological and political actors

The Global Navigation Satellite System (GNSS) is the main element of the CNS/ATM system elaborated by the International Civil Aviation Organization (ICAO).<br>The US GPS and Russian GLONASS are the two existing systems. Both of them were created by the military.<br>Europe is currently developing a civil navigation satellite system: Galileo.<br>This thesis will present some legal issues of the GNSS discussed in the framework of ICAO: sovereignty of States, universal accessibility, continuity and quality of the service, cost recovery and financing, certification and liability.<br>It will also present some legal issues due to the creation of the European Galileo program. The financing, organizational framework, certification and liability will be examined. Finally, ICAO's Charter on the Rights and Obligations of States Relating to GNSS Services will be considered.

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 143-148).<br>The European Satellite Navigation Program is a case study that combines Technical / Public / Private aspects in an integrative way. Therefore, it is a sound case for a TPP thesis candidate. This thesis analyzes the European Union policies for the Galileo program, Europe's bid to have its own Global Navigation Satellite System (GNSS). Galileo is the Europe's first major attempt to develop a complex, Pan-European infrastructure project, to be owned by the European Union. It challenges its capability to gather strength and achieve the political capability to deal with major technology policy projects to lead in world affairs. It is a unique case that serves as a precedent for further infrastructure/technical projects to be managed by European Union institutions in the future. Such a major technology policy project involves the interrelation of a complex structure of multinational political and industrial organizations, and the interrelation of leading edge technical, economic, commercial and social concerns in the heart of the European Communities. During the last two decades Europe has committed to maintain a remarkable long-term vision and a strong political determination to developing Galileo. On the downside, the EU hashad difficulties in establishing a coherent financing program and a punctual manufacturer deployment. On the basis of the Galileo endeavor,this thesis assesses the use of Public Private Partnerships in large pan-European infrastructure projects in the complex political framework of the European Union. This analysis is performed upon the perspective of a theory of how to devise a strategy, a tactical plan, and a way to implement a technology policy effectively, developed by the guidelines set forth by the MIT Technology and Policy Program. It reviews the history of the European Union's policies attempting to develop Galileo, evaluates the strengths and weaknesses of such policies, and delivers a plan and a guide to help implement future projects more effectively. Finally, it aims to provide a set of recommendations for the future policymaking the European Union will face in the next decades with regard to the operation and exploitation of the system.<br>by Laura Escudero San José.<br>S.M.in Technology and Policy

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California<br>Free-space optical communications offer the technology breakthrough required by future Earth Exploration Satellites for their High Rate Payload Telemetry, while they required clear sky propagation conditions leading to locate receiving optical ground stations on favorable sites in terms of atmospheric propagation and to use site diversity to reach classical system availability requirements. This paper presents a methodology that can be used to optimize such a network relying on experimental meteorological satellite data. It also presents quantitative results in terms of link availability over a European ground network and the associated downlink capacity considering possible future Low Earth Orbit satellites.

La microstructure des surfaces planétaires glacées évolue sous l'influence d'une interaction complexe de processus physiques couplés. Cette thèse consiste en la construction d'un modèle de simulation multiphysique "LunaIcy", qui intègre une calcul précis du flux solaire, un solveur thermique stable et rapide, un modèle raffiné de métamorphisme de la glace, ainsi qu'un modèle de cristallisation par température et d'amorphisation par jardinage spatial. L'ensemble de ces processus sont interdépendants, et ce travail représente la première tentative en sciences planétaires d'étudier leur interaction couplée sur une échelle de temps du million d'année, avec une application spécifique à Europe, lune de Jupiter.Tout comme les modèles de circulation générale (GCMs) sont devenus des outils essentiels pour étudier l'évolution des atmosphères planétaires, nous anticipons un développement de ces outils de simulation multiphysique pour l'étude des surfaces planétaires. Simuler ces processus hautement couplés contribue notamment à améliorer l'estimation des contraintes sur la taille des grains ou le taux de cristallisation de la glace. Ces avancées permettront d'affiner l'interprétation des mesures de surface telles que la spectroscopie et la spectro-photométrie, ce qui est essentiel pour l'analyse des observations passées et pour les futures missions telles que JUICE et Europa Clipper<br>The microstructure of icy planetary surfaces evolves under the influence of a complex interplay of coupled physical processes. This thesis consists in the construction of a multiphysics simulation model "LunaIcy", which integrates an accurate solar flux calculation, a stable and fast thermal solver, a model of ice metamorphism/sintering, as well as a model of crystallization by temperature and amorphization by irradiation. These processes are interdependent, and this work represents the first attempt in planetary science to study their coupled interactions on a million-year timescale, with a specific application to Europa, a satellite of Jupiter.Similar to how General Circulation Models (GCMs) have become essential tools for studying the evolution of planetary atmospheres, we anticipate further development of these multiphysics simulation tools for studying planetary surfaces. Simulating these highly coupled processes allows for better estimation of constraints on grain size or ice crystallization rates. These advancements will help refining the interpration of surface measurements such as spectroscopy and spectro-photometry, which is essential for analyzing past observations and for future missions such as JUICE and Europa Clipper

The study aims to offer a clarification and a recognition of the general international and European regulation of remote sensing and, meanwhile, to point out the special regime applicable to remote sensing programs carried out for the prevention, mitigation and management of natural disasters, and to the sensed images relevant in the same field. This hermeneutic method guides the analysis, which aims to propose a fair balance between two opposite demands: on the one hand the promotion of the development of the remote sensing sector through private investment, and on the other hand the proper protection of the public interest in the field of disaster management lato sensu, with the corollary of the prevalence of the logic of solidarity with the one of profit. After introducing fundamental concepts such as remote sensing, natural disaster, outer space, taking into account the relevant regulation, the legal questions arising from the launch of the satellite to the diffusion and use of sensed images are identified and analysed in depth, using the general principles of international space law and international environmental law and examining the praxis shaped by space operators and humanitarian organizations. The research focuses on the unique international instrument specifically dedicated to remote sensing, the General Assembly Resolution 41/65 of 1986. Therefore its correspondence to general international law is scrutinized principle by principle. Next the research explores the international cooperation that has developed in the field of natural disaster management through remote sensing and in particular the system created by the International Charter on Space and Major Disasters on the global level and by the European Union on the regional level. Furthermore, concerning the rules applicable to the access of sensed data, the study analyses how the restrictions to access and diffusion foreseen by national space legislations, even the recently adopted ones, can be conciliated with the unconditioned duty of early warning and of the assistance that international law provides for natural disasters. The conclusion is in a sense that, whenever sensed data are relevant in the sector of natural disasters, all the imposed exceptions and restrictions fall down. Finally, with regard to the legal instruments of protection of remote sensing satellites and of sensed data, during the downlink phase and on fixed support, their gaps and the need of clarification are stressed. Even if it is necessary to guarantee an adequate degree of protection of intellectual property for sensed data, whatever their level of elaboration is, the study supports the thesis that protection should be ignored if data are relevant for natural disaster management, in order to increase their diffusion. In short in the study the access to data relevant for natural disaster management is treated as a public service (servizio pubblico, offentiche Aufgaben, service public) of the international community and as an essential element of a gradually evolving system founded in solidarity among all States participating in the remote sensing chain and on the principle of common benefit for which the exploration and use of outer space shall be carried out according to art. I of the Outer Space Treaty.<br>Il presente lavoro mira ad offrire una chiarificazione e ricognizione della disciplina generale internazionale ed europea del remote sensing e nel contempo ad individuare il regime speciale applicabile ai programmi di remote sensing condotti per la prevenzione, la mitigazione e la gestione dei disastri naturali e alle immagini telerilevate rilevanti nello stesso ambito. Tale opera ermeneutica, che ne costituisce il filo conduttore ed unificante le varie parti, è animata dall’obiettivo di proporre un equo bilanciamento fra due esigenze contrapposte: quella di promuovere lo sviluppo del settore del remote sensing stimolando l’investimento privato e quella di tutelare adeguatamente l’interesse pubblico in materia di gestione, in senso lato, dei disastri naturali con il corollario della prevalenza, in tale ambito, della logica della solidarietà su quella del profitto. Dopo una parte introduttiva dedicata alla definizione, alla stregua della normativa rilevante, di alcuni concetti fondamentali come telerilevamento, disastro naturale, spazio extra-atmosferico, vengono enucleate e sviscerate le questioni giuridiche che il remote sensing pone durante tutto il suo svolgimento, dal lancio del satellite da telerilevamento fino al momento della diffusione e dell’utilizzo delle immagini telerilevate, facendo ampio appello ai principi generali di diritto internazionale spaziale e dell’ambiente ed esaminando la prassi che si sta sviluppando ad opera degli operatori spaziali e delle organizzazioni di carattere umanitario. In questa parte viene dedicata particolare attenzione all’unico strumento internazionale dedicato in modo specifico al remote sensing, la risoluzione dell’Assemblea Generale 41/65 del 1986, la cui corrispondenza al diritto internazionale generale viene pertanto vagliata principio per principio. L’indagine si concentra poi sulla cooperazione internazionale che si è sviluppata nel settore della gestione tramite remote sensing dei disastri naturali, prendendo in esame più da vicino il sistema messo a punto a livello globale dall’International Charter on Space and Major Disasters e, a livello regionale, dall’Unione Europea. E’apparso poi necessario analizzare la disciplina applicabile all’accesso ai dati telerilevati in particolare per verificare come le restrizioni all’accesso e alla diffusione previste da tutte le legislazioni spaziali nazionali, anche di recente adozione, interagiscono e possono essere conciliate con l’incondizionato obbligo di avviso (early warning) e di soccorso che il diritto internazionale pone in caso di disastri naturali concludendo nel senso che, quando i dati telerilevati sono rilevanti nel settore dei disastri naturali, cadono tutte le eccezioni e le restrizioni eventualmente imposte. Passando infine a considerare gli strumenti utilizzabili a protezione dei satelliti da telerilevamento e degli stessi dati telerilevati, nella fase di downlink o su supporto fisso, ne vengono messe in evidenza le lacune e viene sottolineata l’esigenza di chiarificazione che permea la materia. Ferma la necessità di garantire una adeguata protezione della proprietà intellettuale ai dati telerilevati, quale sia il loro livello di elaborazione, si ritene che tale protezione dovrebbe venir meno se i dati sono rilevanti nella gestione dei disastri naturali, a tutto vantaggio della loro più ampia condivisione. In sintesi nel presente lavoro l’accesso ai dati telerilevati rilevanti nella gestione dei disastri naturali viene configurato come un servizio pubblico (public service, offentiche Aufgaben, service public) della comunità internazionale e si pone come elemento essenziale di un sistema in corso di progressiva definizione fondato sulla solidarietà fra tutti gli Stati partecipanti alla catena della attività telerilevanti e sul principio del beneficio comune cui debbono essere finalizzate, ai sensi dell’art. I del Trattato sullo spazio, l’esplorazione e l’utilizzazione dello spazio extra-atmosferico.

The Great Cormorant (Phalacrocorax carbo), actually in expansion is a large colonial piscivorous migrating waterbird. In Europe, two sub-species, carbo and sinensis, are distinguished according to morphological, ecological and geographical criteria. This work has focused on the evolutionary history of populations, the validity of the subdivision in two sub-species, and the ecological specialisation. The main results are: (i) the phylogeographical study shows the existence of a third sub-species in Europe and the convergence of the populations to the western part of Europe; (ii) the analysis of the population structure (microsatellites) show pattern of isolation by distance, with an effect of long-dispersal distance linked to the migratory axis; (iii) the monitoring of the breeding success show that the sinensis subspecies is better adapted to the inland habitat than carbo subspecies<br>Le Grand Cormoran (Phalacrocorax carbo), est un oiseau colonial piscivore migrateur de grande taille, actuellement en expansion. En Europe, deux sous-espèces, carbo et sinensis, sont distinguées : critères morphologiques, écologiques et géographiques. Ce travail visait à étudier l'histoire évolutive des populations, à tester la pertinence de la sub-division en deux sous-espèces et à vérifier l'hypothèse de spécialisation écologique, grâce à des méthodes moléculaire et de suivi sur le terrain. Les résultats majeurs sont : (i) l'étude phylogéographique (ADNmt) montre l'existence d'une 3^ème sous-espèce européenne et la convergence des populations vers l'ouest de l'Europe ; (ii) l'analyse de la structure de population (microsatellites) montre une isolation par la distance, avec un effet de dispersion longue-distance, en lien avec la migration ; (iii) l'étude du succès reproducteur montre que la sous-espèce sinensis est mieux adaptée au milieu continental que carbo (spécialisation écologique)

In the recent years small satellites technology is growing up very fast. The use of a small sized spacecraft allows to reduce the costs of construction and launch without make particular compromise in terms of scientific objectives. Recently the small satellites have been used also as complement in a deep space mission and so new engineering challenges have born. The purpose of this master thesis rely on a particular small satellites mission concept that would improve the gravity investigations accuracy of a target body but with a lower cost. This mission case is based on the employment of a pair of small satellites that use the Satellite-to-Satellite Tracking technique to generates the observable quantities used for the orbit determination process and for the scientific analysis. These observables are two-way Doppler data obtained from the frequency shift of a stable microwave carrier transmitted between the two spacecrafts. Through these measurements it is possible to determine the static and dynamic gravity field of a body. The utilization of the SST, together with the small satellites technology, would certainly reduce the complexity and the costs, with an increment of estimation accuracy, but with the introduction of new potential engineering problems. The targets of the proposed SST mission concept are Titan, Enceladus and Europa. In each of these mission cases the two smallsats are placed on the same orbit, with a given angular separation. The objectives of this thesis were focused on the analysis of the SST technique, the numerical simulation of the orbit determination of the spacecrafts and the obtainable accuracy of the moon's gravity field estimation. Following these targets different orbital geometries were studied, to identify the most promising configurations. All the numerical evaluations have been conducted with the astro available at the Radio Science and Planetary Exploration Laboratory of the University of Bologna.

L'objectif de la thèse est de développer des méthodes de cartographie et de suivi des cultures basées sur des données de télédétection, radar et optique. Les résultats pourront être combinés avec d'autres techniques, notamment avec des modèles de croissance des cultures, pour améliorer la prévision des récoltes. Quatre instruments différents, 3 sur satellite (LANDSAT-TM, ENVISAT-MERIS, ENVISAT-ASAR) et 1 aéroporté (AIRSAR) sont utilisés dans trois régions d'étude en Europe (Barrax, Toulouse et Flevoland). Les travaux sont présentés en deux parties, optique et radar. Dans la première partie, les données LANDSAT sont utilisées pour l'inversion du LAI à Barrax (Castilla-La Mancha) à l'aide du modèle de transfert radiatif PROSPECT+SAIL. Les résultats sont validés avec des mesures expérimentales acquises au cours de la campagne sur le terrain ESA SPARC-2003, montrant une bonne corrélation. Une méthode est ensuite proposée pour inverser le LAI et la chlorophylle à partir de données MERIS. La méthode implique une inversion du modèle, PROSPECT+SAIL avec une contrainte temporelle (une courbe pour l'ensemble du cycle de culture est inversée). Les résultats montrent que cette méthode fonctionne mieux que les inversions date par date. Toutefois, l'inversion de la chlorophylle nécessite encore une étude plus approfondie. Dans la partie radar, une méthode de classification basée sur les connaissances des mécanismes de rétrodifusion est proposée. Elle utilise des données polarimétriques en bande C de l'instrument AIRSAR. La méthode est appliquée à des images dans le Flevoland (Pays-Bas). Les résultats indiquent que ces méthodes peuvent être plus robustes que les méthodes statistiques usuelles. .<br>El aumento de la población mundial, así como la importancia social y económica que el sector agrícola tiene en muchas regiones del mundo, hace que sea muy importante desarrollar métodos que permitan hacer un seguimiento del estado de los cultivos, mejorar la gestión de los mismos, así como poder realizar una estimación temprana de la producción. La principal causa de incertidumbre en la producción de las cosechas es debida a las condiciones meteorológicas, por ejemplo, en las regiones áridas y semiáridas del mundo los períodos de sequía generan grandes pérdidas en la producción agrícola, la cuales se traducen en hambrunas. Así, la FAO, durante su cumbre de Junio 2008, insistió en la necesidad de aumentar a producción agrícola como una medida para reforzar la seguridad alimentaria y reducir la desnutrición en el mundo. La preocupación por aumentar la producción de cultivos, ha generado, durante las últimas décadas, importantes cambios en las técnicas agrícolas. Por ejemplo, se ha producido un uso generalizado de productos fitosanirios, de cultivos modificados genéticamente, así como un aumento de la agricultura intensiva. A su vez, la rotación de cultivos está cada vez más influenciada por el mercado, siendo los cambios en la distribución espacial de los cultivos muy frecuentes. Por lo tanto, para poder hacer estimaciones de la producción agrícola, es necesario producir eriódicamente mapas de cultivos, así como cartografiar su estado de desarrollo. La presente tesis doctoral tiene como objetivo desarrollar métodos basados en datos de teledetección, en la región del óptico y en la región del radar, que permitan realizar un seguimiento de los cultivos, así como una cartografía de los mismos. Los resultados de esta tesis pueden combinarse con otras técnicas, especialmente con los modelos de crecimiento de cultivo, para mejorar la predicción de las cosechas. Los métodos de teledetección para la clasificación y la cartografía de cultivos utilizando datos en la región del óptico están bien establecidos y pueden considerarse casi operacionales. La desventaja de estos estudios basados en datos ópticos es que no pueden aplicarse a regiones donde la cobertura nubosa es frecuente. En esos casos, la utilización de datos radar es más recomendable. Sin embargo, los métodos de clasificación utilizando datos radar no están tan bien establecidos y es necesario realizar más estudios científicos en este campo. Es por ello, que esta tesis se centra en la clasificación de cultivos mediante datos radar, concretamente datos aerotransportados AIRSAR y datos ASAR del satélite ENVISAT. El seguimiento de los cultivos mediante teledetección se basa en la estimación de parámetros biofísicos y su evolución en el tiempo. Estos parámetros son, entre otros, LAI (índice de área foliar), clorofila y biomasa. En esta tesis se han utilizado datos del satélite LANSAT-TM para la inversión de LAI, y datos ENVISAT-MERIS para la estimación de LAI y clorofila

Europa is one of the most interesting satellites in the solar system in the search ofextra-terrestrial life, as it harbours an interior water ocean under its icy surface. Watervapour in Europa’s atmosphere has been previously observed, suggesting water plumeeruptions from the surface. These plumes could potentially originate from the subsurfaceocean, and as such contain ocean constituents that can be examined in orbit. Twoobservations of Europa’s far-ultraviolet shadow on Jupiter were made by the HubbleSpace Telescope in 2018 and 2019. It was observed in Lyman-α (1 216 Å), a spectral lineof hydrogen. This study investigates the imaged Lyman-α shadow in search of potentialplumes at the shadow limb. Examining the shadow instead of the moon itself is a newmethod of remotely studying the Europan atmosphere. Forward modelling is applied tocreate artificial images that are compared to the observations. Any anomalies aroundthe shadow limb are then analysed and evaluated for their statistical significance. Twonoteworthy outliers are found at the limb (one on each occasion) corresponding to H2Oline of sight column densities of 3.07×1017 cm−2 and 4.72×1016 cm−2, for the 2018 and2019 observation, respectively. They are not significant however, as they lie within threestandard deviations from the expected value (&lt; 3σ). An upper limit on what columndensity is detectable in the data is computed, yielding 6.71×1016 cm−2 (using only 2019data due to a weak signal on the 2018 occasion). A constraint on the maximum possibleH2O column density at Europa is thus provided. The new method is shown to be usefulfor the intended purpose and could potentially be applied on other icy moons.<br>Europa är ett av solsystemets mest intressanta objekt i jakten på utomjordiskt liv, dådet finns ett hav av vatten under månens isiga yta. Vattenånga har tidigare observeratsi Europas atmosfär, vilket kan tyda på vattenplymer som skjuts ut från ytan i kraftigautbrott. Dessa plymer kan möjligtvis ha sitt ursprung i månens inre hav, de kandärför möjliggöra en analys av havsvattnets beståndsdelar i omloppsbana. Europasultravioletta skugga på Jupiter observerades vid två tillfällen 2018 och 2019, av HubbleSpace Telescope. Observationerna gjordes i Lyman-α (1 216 Å), en spektrallinje hos väte.Denna studie undersöker den avbildade skuggan i Lyman-α för att söka efter potentiellavattenplymer vid skuggans rand. Att undersöka skuggan istället för själva månen är en nymetod för att studera Europas atmosfär genom fjärranalys. Metoden forward modellinganvänds för att skapa artificiella bilder, som jämförs med observationerna. Eventuellaavvikelser som hittas runt skuggans rand analyseras sedan och deras statistiska signifikansutvärderas. Två anmärkningsvärda avvikelser kan hittas vid randen (en vid varjeobservationstillfälle), som motsvarar H2O-kolumndensiteter på 3.07 × 1017 cm−2 och4.72 × 1016 cm−2, för 2018-observationen respektive 2019-observationen. Densiteternaär dock inte signifikanta, då de ligger inom tre standardavvikelser från deras förväntadevärden (&lt; 3σ). Istället beräknas en övre gräns för vilken kolumndensitet som kandetekteras i datan, vilket ger 6.71 × 1016 cm−2 (där endast 2019-data används på grundav en svag signal hos 2018-observationen). Den högsta möjliga H2O-kolumndensitetenkan således begränsas. Den nya metoden visar sig vara användbar för det tänkta syftetoch kan eventuellt appliceras på andra ismånar.

Mestrado em Economia e Políticas Públicas<br>Uma Conta Satélite do Desporto (CSD) apura agregados macroeconómicos referentes ao Desporto. A CSD portuguesa, no seu processo de compilação, utilizou os princípios subjacentes às Contas Nacionais (CN), como as atividades, nomenclaturas, etc. O processo de estimação do peso do Desporto, consistiu em considerar os dados disponíveis e convertê-los em informação económica agregada por atividades, modalidades e agentes. Recorrendo à aplicação dos algoritmos utilizados pelas CN a dados contabilísticos de unidades estatísticas selecionadas e/ou à aplicação de coeficientes determinados a partir de outras fontes. A construção de políticas públicas recomenda que o papel da função de avaliação deve ser claramente definido e distinto dos papéis de outras funções, como a monitorização, o controle e a auditoria. A avaliação ex-ante correspondeu ao Estudo de viabilidade (avaliação inicial), onde foram avaliadas as condições de exequibilidade da CSD. A deteção de possíveis dificuldades levou à inclusão, de algumas recomendações, no âmbito da criação de uma estrutura de informação direcionada para as federações, os clubes e as empresas de Desportos. Pode dizer-se que esta política pública está a ser implementada com sucesso. A Fase I (Estudo Viabilidade) foi cumprida, de acordo com o previsto, estando neste momento, a ser elaborado o relatório final, sendo posteriormente divulgado. Os principais resultados previstos, serão estimativas, para as seguintes variáveis: Produção; Consumo Intermédio; Valor Acrescentado Bruto; Excedente Bruto de Exploração; etc. A divulgação destes dados permitirá conhecer com maior profundidade a realidade económica do Desporto em Portugal, oferecendo uma melhor fundamentação para futuras políticas públicas, na matéria.<br>The Portuguese Sports Satellite Account (SSA) used the principles of the National Accounts (NA), such as activities, classifications, etc. The estimation process of the Sports weight consisted on, gathering the available data and convert them into economic information for aggregate activities, modalities and agents. By applying the algorithms used by NA to accounting data of statistical unit selected and/or the application of coefficients determined from other sources. The construction of public policy recommends that the evaluation function must be clearly defined and distinct of other functions, such as monitoring, control and audit. In this case, the initial evaluation matched the feasibility study (baseline), in which the conditions of feasibility of the SSA where evaluated. The detection of possible difficulties led to the inclusion of some recommendations within initial evaluation such as, the creation of an information structure directed to the federations, clubs and sports companies. This public policy is being implemented with success. Phase I has been fulfilled, according to plan, and currently, is being prepared the final report. The main results expected are estimates for the following variables: production; Intermediate consumption; Gross Value Added; Gross Operating Surplus; Employment; Compensation of employees; Other subsidies on production; Other taxes on production; Import and Export of goods and sports services; Financing of sport; Final consumption expenditure (households, non-profit institutions, companies and public administration). The disclosure of this data will reveal, in greater depth the economic reality of sport in Portugal, providing a better foundation for future public policy in this area.

Le Alpi sono state colpite dall'intensificarsi della siccità meteorologica negli ultimi anni. A causa delle mutevoli condizioni climatiche, la regione è vulnerabile alle deviazioni nel ciclo dell'acqua, che possono essere osservate nel contesto delle anomalie dell'evapotraspirazione (ET). La temperatura della superficie terrestre (LST) è un fattore chiave nella regolazione dello scambio di acqua ed energia tra terra e atmosfera, che la mette in relazione direttamente con ET. Lo sviluppo di modelli di bilancio energetico a due fonti (TSEB) guidati da dati di telerilevamento termico ha dato un contributo significativo alla stima dell'ET su larga scala. Tuttavia, la loro risoluzione spaziale grossolana e la sensibilità degli strumenti TIR alle condizioni del cielo nuvoloso li rendono insufficienti per ecosistemi complessi, come le regioni di montagna. Per superare queste limitazioni, questa tesi è servita per sviluppare un nuovo prodotto della temperatura della superficie terrestre in cielo sereno con una risoluzione spaziale di 250 m, in alternativa ai dati MODIS LST di 1 km, per la stima dei flussi TSEB a risoluzione fine. Nella prima parte della tesi, lo squilibrio tra la risoluzione spaziale dei dati MODIS LST di 1 km è stato risolto applicando una procedura di sharpening per ottenere LST giornaliero a una risoluzione spaziale di 250 m. A causa delle ridotte capacità dei modelli statistici LST-VNIR in ecosistemi complessi, sono stati utilizzati predittori multi-sorgente, tra cui l'indice di NDVI e il DEM. Ispirato dalla superiorità dell'apprendimento automatico per problemi non lineari, sono state sfruttate le relazioni tra LST a risoluzione grossolana e predittori di 250 m con algoritmo a foresta casuale (RF). I risultati ottenuti indicano un miglioramento del 20% nell'accordo tra Landsat e l'affilato LST rispetto alle statistiche per il set di dati MODIS originale. I modelli LST hanno determinato un RMSE medio di 2,3°C e un MAE di 1,8°C. Al fine di ricostruire gli LST mancanti sotto le nuvole, l'autore ha proposto un nuovo approccio per prevedere i pixel non validi sfruttando la correlazione tra LST a terra e temperatura dell'aria in combinazione con variabili ausiliarie, ad esempio radiazione solare discendente, albedo e LAI sotto cieli nuvolosi a lungo termine. Considerando un'elevata dipendenza del sito determinata da diversi tipi di copertura del suolo, la ricostruzione LST è stata eseguita per stazioni aggregate che rappresentano tre gruppi di vegetazione: praterie, foreste e colture permanenti. Il gap-filling è stato eseguito con due passaggi: modellazione LST basata sul sito da variabili derivate dal suolo sotto cieli nuvolosi e quindi applicazione dei modelli adattati a predittori a griglia a livello di subpixel corrispondenti all'output ridotto. La ricostruzione ha ottenuto prestazioni affidabili con dati locali che producono R2 di 0,84 e RMSE di 2,12°C. Nell'ultima parte della tesi, le mappe LST risultanti sono state incorporate nel modello di bilancio energetico a due fonti di Priestley-Taylor per la stima dei flussi energetici a una risoluzione spaziale di 250 m. Innanzitutto, le prestazioni del modello forzato dalle temperature locali sono state valutate con flussi misurati da torri di eddy covariance. Le simulazioni di riferimento per il calore latente (LE) e sensibile (H) hanno prodotto un RMSE medio di 57 Wm-2 e un bias assoluto medio (MB) di 26 Wm-2. Successivamente, le stime del modello guidate da LST basati su satellite, ovvero il prodotto LST MODIS originale di 1 km e le mappe ridimensionate, sono state convalidate rispetto ai dati in situ. Flussi turbolenti modellati con LST di 250 m hanno portato a RMSE di 86 Wm-2 e MB di 55 Wm-2, che si sono tradotti in una diminuzione dell'8% e del 15% nei rispettivi errori rispetto alle stime TSEB combinate con l'LST MODIS originale.<br>The European Alps have been affected by intensification of meteorological droughts in recent years. Due to changing climatic conditions, the region is vulnerable to deviations in water cycling, which can be observed in the context of evapotranspiration (ET) anomalies. Land surface temperature (LST) is a key factor in regulating the exchange of water and energy between land and atmosphere, which directly relates it to ET. Development of two-source energy balance (TSEB) models driven by thermal remote sensing data has made a significant contribution to estimate ET at large scale. However, their coarse spatial resolution and sensitivity of TIR instruments to cloudy-sky conditions make them insufficient for complex ecosystems, such as mountain regions. To overcome these limitations, this thesis served to develop a new clear-sky land surface temperature product at 250 m spatial resolution, as an alternative to 1-km MODIS LST data, for estimating fine-resolution TSEB fluxes. In the first part of the thesis, imbalance between spatial resolution of 1-km MODIS LST data was solved by applying a sharpening procedure to obtain daily LST at 250-m spatial resolution. Due to reduced capabilities of LST–VNIR statistical models in complex ecosystems, multi-source predictors, including normalized difference vegetation index (NDVI) and digital elevation model (DEM) were used. Inspired by superiority of machine learning for non-linear problems, relationships between coarse resolution LSTs and 250-m predictors with random forest (RF) algorithm were exploited. The obtained results indicate an improvement of 20% in the agreement between Landsat and the sharpened LST compared to statistics for the original MODIS dataset. The LST models determined averaged RMSE of 2.3°C and MAE of 1.8°C. In order to reconstruct missing LSTs beneath the clouds, the author proposed a novel approach to predict invalid pixels by exploiting correlation between ground-based LST and air temperature in conjunction with auxiliary variables, e.g., downwelling solar radiation, albedo- and LAI-derived products under long-term cloudy-skies. Considering a high site dependency driven by different land-cover types, LST reconstruction was performed for aggregated stations that represent three vegetation groups: grassland, forest and permanent crops. The gap-filling was performed with two steps: site-based LST modelling from ground-derived variables under cloudy skies, and then applying the fitted models to gridded predictors at subpixel level corresponding to the downscaled output. The reconstruction achieved reliable performance with local data yielding R2 of 0.84 and RMSE of 2.12°C. In the last part of the thesis, the resulting LST maps were incorporated into two-source energy balance model of Priestley-Taylor for estimating energy fluxes at 250-m spatial resolution. First, the performance of the model forced by local temperatures was evaluated with measured fluxes from eddy covariance towers. The benchmark simulations for latent (LE) and sensible heat (H) yielded an averaged RMSE of 57 Wm-2 and mean absolute bias (MB) of 26 Wm-2. Next, the model estimates driven by satellite-based LSTs, i.e., original 1-km MODIS LST product and downscaled maps, were validated against in-situ data. Turbulent fluxes modelled with 250-m LSTs resulted in RMSE of 86 Wm-2 and MB of 55 Wm-2, which translated to 8% and 15% decrease in the respective errors when compared to TSEB estimates combined with original MODIS LST.

This thesis studies hydrated oxygen and hydroxyl radicals as a basis for understanding the species formed in the icy surfaces of outer solar system bodies. Infrared spectroscopy is used to identify the species water-oxygen (H2O·O2) and water-hydroxyl (H2O·HO) complexes in inert gas matrices and presents a new mechanism for O2 formation in irradiated ices. The H2O·O2 Complex -- The H2O·O2 complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of H2O⁄O2⁄Ar matrices. Absorption bands at 3731.6, 3638.3, 1590.2⁄1593.6 and 1551.9⁄1548.8 cm-1 were respectively assigned to asymmetric OH water stretching, symmetric OH water stretching, H2O bending, and the O2 stretching vibrations. This experimental data was in good agreement with the results of quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·O2. These calculations gave a binding energy of 0.72 kcal mol-1 for the complex. The H2O·HO Complex -- The H2O·HO complex was identified in solid argon matrices at 11 K by measuring the infrared spectra of OH⁄H2O⁄Ar matrices. The OH was formed in a Tesla coil discharge of an H2O⁄Ar gas stream. This gas stream also provided the source of H2O and Ar needed for the experiments. Three absorption bands were assigned to the OH stretch of the hydroxyl group in the complex. These three bands were caused by the occupancy of three different lattice sites. This experimental data was in good agreement with quantum mechanical calculations that predict the vibrational frequencies and intensities for H2O·HO. These calculations gave a binding energy of 5.69 kcal mol-1 for the complex. O2 Formation in Irradiated Ice -- A new mechanism for O2 formation in irradiated ice is presented. This mechanism draws on experimental evidence in the literature to explain the observations of solid O2 on or near the surface of the icy Galilean satellites, Europa and Ganymede. It is proposed that on these bodies, hydrogen peroxide, formed from the radiolysis and photolysis of the ice, is present in highly localized aggregates that hinder O2 diffusion out of the icy surface into the tenuous atmosphere. Further radiolysis and photolysis of these hydrogen peroxide aggregates can then lead to O2 formation via the formation of a short lived water-oxygen atom complex, H2O·O. The O atoms of a pair of these complexes then react rapidly to form O2

La qualité de l'air est un enjeu sociétal important et son évolution en lien avec le changement climatique reste mal évaluée. Sa surveillance est donc un objectif principal des prochaines années pour la santé publique et des écosystèmes. L'ozone, qui est un produit secondaire, lorsqu'il est présent en trop grande concentration dans la basse troposphère, a des conséquences délétères sur la santé et la végétation, il est donc important de surveiller sa concentration et de disposer des outils les mieux adaptés pour prévoir au mieux les épisodes de pollution à l'ozone. Pour surveiller et prévoir la qualité de l'air aux échelles régionales et continentales, les réseaux de surface s'avèrent insuffisants, l'information sur la distribution verticale de l'ozone devenant un élément important à prendre en compte à ces échelles. Les observations satellitaires de la composition chimique de la troposphère, qui se sont fortement développées ces dernières années, commencent à apporter une information pertinente sur l'ozone troposphérique en donnant cette composante verticale. Cependant, l'accès aux plus basses couches de la troposphère reste encore limité. Il est donc important de s'interroger et d'évaluer l'apport des futures missions satellitaires dans ce domaine. L'objectif de cette thèse porte donc sur l'évaluation du futur instrument IASI-NG, qui sera embarqué sur la plateforme MetOp-SG d'EUMETSAT aux environs 2020, pour la surveillance de la qualité de l'air en Europe. Nous nous sommes en particulier focalisés sur l'évaluation des performances de cet instrument pour mesurer l'ozone dans la basse troposphère et son impact sur les systèmes d'analyse et de prévision de la qualité de l'air. Cette évaluation a été faite en comparaison avec les performances de l'instrument IASI. Dans un premier temps, nous avons cherché à amliorer l'algorithme de restitution de l'ozone troposphérique en optimisant la sélection des fenêtres spectrales ou canaux spectraux. Nous avons élaboré une méthode permettant de sélectionner les meilleurs canaux pour la restitution de l'ozone dans la basse troposphère, c'est-à-dire contenant le maximum d'information sur l'ozone et les moins contaminés par les espèces ou paramètres interférents. Cette méthode a été appliquée à plusieurs configurations instrumentales actuelles ou futures (IASI, IASI-NG et MAGEAQ). Dans un second temps, nous nous sommes attachés à quantifier l'apport d'IASI-NG pour la caractérisation de la qualité de l'air à l'échelle européenne. Nous avons pour cela mis en oeuvre des expériences de simulation de systèmes d'observation (OSSE). Une première étape a consisté à évaluer les améliorations en termes de restitution de l'ozone troposphérique en comparaison avec IASI. On a en particulier montré qu'avec IASI-NG il sera possible de distinguer l'ozone de la basse et la haute troposphère quelque soient les conditions atmosphériques. Une deuxième étape a consisté à l'analyse des résultats des OSSEs. Le travail de thèse a en particulier montré toute l'importance de la calibration de l'OSSE pour une bonne réalisation et analyse des résultats. Nous avons montré que les observations IASI-NG, si elles sont assimilées dans des modèles de qualité de l'air, devraient améliorer la représentation des champs d'ozone simulés notamment en termes de corrélation<br>Air quality is a major societal issue with severe implications on human health and ecosystems and its evolution in the climate change context is not well known. Then, monitoring of air quality is an important objective for the following years. Ozone, secondarily produced in the atmosphere, is a harmful pollutant when its concentrations in the lower troposphere become larger than some exposure thresholds. It is then important to monitor its concentrations and to have the best adapted tools to forecast pollution events. In order to monitor and forecast air quality at the regional and continental scales, surface networks are insufficient because the vertical distribution of ozone becomes a key parameter to understand its distribution even in the lowermost troposphere. Satellite observations of the tropospheric composition have been largely developed since the last decade and start to bring useful information on tropospheric ozone given the vertical component of its distribution. However, the access to the lowermost troposphere remains limited. It is then important to quantify the improvement expected with future satellite missions. The main objective of this thesis is to evaluate the future instrument IASI-NG, which will be aboard the EUMETSAT MetOp-SG platform around 2020, for the air quality monitoring in Europe. We focused on the quantification of the performances of IASI-NG to measure ozone in the lower troposphere and the impact of this future instrument on the analysis and forecast systems of air quality. This evaluation has been done in comparison with the current performances of the IASI instrument. Firstly, we worked on the improvement of the retrieval algorithm of tropospheric ozone by optimizing the spectral window selection. We developed a method that allows the selections of the best spectral channels for the retrieval of ozone in the lower tropospher, i. E. Including the maximum of information on ozone and the least contamined by interfering species or variables. This method has been applied to several instrumental configurations (IASI, IASI-NG and MAGEAQ). Secondly, we quantified the impact of IASI-NG for the characterization of air quality at the European scale. For this, we implemented Observating System Simulation Experiments (OSSEs). A first step was to evaluate the improvements of IASI-NG for the retrieval of tropospheric ozone in comparison with IASI. We show in particular, that it will be possible to separate information on ozone from the lower ant the upper troposphere with IASI-NG whatever the atmospheric conditions. A second step was the analysis of the OSSEs results. This work showed the necessity of good calibration of the OSSE in order to correctly analyze the results. We showed that the IASI-NG observations, when assimilated in air quality modelsl, should improve the description of simulated ozone fields especially in terms of correlation

On se propose dans un premier temps d'étudier des jeux de données topographiques sur la lune glacée de Jupiter Ganymède et d'estimer l'impact de la topographie sur les performances du futur radar sondeur. Les principaux résultats sont présentés dans [1]. Une seconde partie est dédiée à l'expression mathématique du problème direct du sondage radar planétaire (physique et instrumentation). On rappelle ainsi comment dériver à partir des formulations de Stratton-Chu les formulations volumiques classiques et surfaciques (i.e. Huygens-Fresnel). On s'attache ensuite à détailler un algorithme performant basé sur la formulation surfacique pour simuler des échos radar à partir d'une surface planétaire maillée. Cette approche est largement inspirée par le travail de J.-F. Nouvel [2]. Une troisième partie s'intéresse à l'inversion des paramètres géophysiques de surface à partir des mesures radar. On écrit ainsi le problème dans un cadre probabiliste (c.f. [3]) et on présente trois grandes familles d'algorithmes : (i) une approche avec une linéarisation du problème, (ii) une approche itérative basée sur une méthode de gradient et (iii) une approche statistique pour estimer les densités de probabilités a posteriori. Ces algorithmes sont appliqués à des jeux de données synthétiques pour illustrer leurs performances. [1] Y. Berquin, W. Kofman, A. Herique, G. Alberti, and P. Beck. A study on ganymede's surface topography: Perspectives for radar sounding. Planetary and Space Science, (0), 2012. [2] J.-F. Nouvel, A. Herique, W. Kofman, and A. Safaeinili. Radar signal simulation: Surface modeling with the Facet Method. Radio Science, 39:RS1013, February 2004. [3] A. Tarantola. Inverse problem theory and methods for model parameter estimation. SIAM, 2005<br>The manuscript details the work performed in the course of my PhD on planetary sounding radar. The main goal of the study is to help designing and assessing the sounding radar performances. This instrument will be embarked on the ac{ESA}'s large class mission ac{JUICE} to probe Jupiter's environment and Jupiter's icy moons Callisto, Ganymede and Europa. As an introduction to the problem, a study on Ganymede's surface ac{DEM} and its implications with regard to the radar performances was performed. The results of this work put forward issues due to a hostile environment with important surface clutter which eventually lead to a decrease in the radar signal bandwidth to 8--10 MHz. A first section is then dedicated to the formulation of the direct problem of sounding radar with a focus on surface formulations. This section eventually leads to a novel algorithm for radar surface echo computation from meshed surfaces which proves to be both efficient and accurate. A second section studies the possibility to use surface formulation to recover geophysical surface parameters from sounding radar data. For that purpose, three main approaches are discussed namely (i) a linear approach, (ii) a gradient-based approach and (iii) a statistical approach. These techniques rely on a probabilistic view of the inverse problem at hand and yield good result with different setups. Although we mainly focus on surface reflectivity, we also discuss surface topography inversion. Finally, a last section discusses the work presented in the manuscript and provides perspectives for future work

This PhD thesis focuses on the analysis of different high energetic processes that affect the surface of planets, satellites and minor bodies as well as modify their surrounding environment. Specifically, this work concerns three main topics: (i) the simulation and analysis of one of the most geological energetic process, i.e. impact cratering; (ii) the investigation of the fragmentation processes that could have generated boulders on comet Churyumov-Gerasimenko 67P; (iii) the analysis of a possible transient plume originating from cryovolcanic events on Europa, the Jovian icy satellite, combined with an accurate characterisation of its exospheric background. The first topic addresses the investigation of the impact formation process through numerical modelling. Shocks code represent the most feasible method for studying impact craters, as they can simulate a large span of conditions beyond the reach of experiments (e.g., velocity, size). The iSALE hydrocode was used to simulate two different impact structures located on Mercury and Mars. On Mercury, the simulation allows to determine the genesis of a particular landform, i.e. a steep-sided cone with associated pyroclastic deposits, which was revealed by images acquired by MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. On Mars, the simulation of the Firsoff crater in Arabia Terra permits a better understanding the subsequent geologic processes that led to crater post modification, defining which rheological structure is more likely in that region. In both cases, we conclude that the numerical modelling of impact process is a powerful tool to improve the comprehension of the Solar System. The second topic of the thesis has been developed after the Rosetta mission got inserted around the comet Churyumov-Gerasimenko 67P. We investigated the surface of comet Churyumov-Gerasimenko 67P focusing on the possible energetic events that lead to the formation of boulders; i.e. blocks that are ubiquitous on the surface of the comet. Different energetic formation processes were invoked to explain the presence of boulders, such as sublimation, fragmentation, outbursts and gravitational falls. Using images acquired by OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) and CIVA (Comet Infrared and Visible Analyser) cameras on board the spacecraft and the lander respectively, a quantitative analysis of different-size boulders has been performed in order to understand if the same energetic formation processes occur equally on different scales on the comet (m, cm and mm). Specifically, by means of different resolution images, we obtained several size-frequency distribution for: (i) boulders larger than 7 m, (ii) boulders larger than 1 m from higher resolution images used to analyse the Abydos site, the location where Philae is supposed to be, and (iii) pebbles (mm-scale structures) visible on CIVA images. The third topic is the icy satellite Europa in view of the future ESA/JUICE mission and because of our involvement in JANUS (Jovis, Amorum ac Natorum Undique Scrutator) visible camera. The presence of a subsurface ocean is a primary topic on Europa, in addition the recent discovery of a transient plume at the south pole by HST observations has raised many questions regarding the interaction between the subsurface/surface and the outer environment of Europa in terms of active processes affecting the icy surface. In this context, a possible plume deposit originating from cryovolcanic events was simulated to understand its detectability by JANUS camera during the Europa flyby phase of the JUICE mission. In addition, since the study of transient plumes has as a mandatory prerequisite an accurate characterisation of the exospheric background, a detailed study of the loss rates of Europa's tenuous atmosphere was performed. In particular, loss rates for electron impact dissociation and ionization processes, for charge-exchange (considering plasma torus, pick up and ionosphere ions) and for photo processes (for both cases of quite and active Sun) were calculated.<br>Il lavoro di tesi è focalizzato sull'analisi di processi fortemente energetici che agiscono e caratterizzano le superfici dei corpi del Sistema Solare (pianeti, satelliti e corpi minori), influenzandone anche l'ambiente circostante. Gli argomenti principali sviluppati in questo lavoro sono i seguenti: (i) simulazione e analisi della fisica dell'impatto su superfici planetarie, (ii) lo studio dei processi di frammentazione responsabili dell'origine dei molteplici massi presenti sulla superficie della cometa Churyumov-Gerasimenko 67P, e (iii) la caratterizzazione di fenomeni transienti che si manifestano sul satellite gioviano Europa, in particolare l'analisi di possibili "plumes'' generati da fenomeni criovulcanici e lo studio accurato dell'ambiente esosferico. Il primo tema affrontato è l'analisi del processo di craterizzazione da impatto tramite simulazioni numeriche, in quanto gli shock code rappresentano il miglior mezzo per esplorare condizioni non raggiungibili in laboratorio e capire quali siano le variabili maggiormente responsabili agenti della formazione del cratere. In questa tesi l'hydrocode iSALE è stato utilizzato per simulare due strutture di impatto presenti su due pianeti del Sistema Solare, Mercurio e Marte. Nel primo caso, la simulazione e analisi del cratere ha permesso di ottenere maggiori informazioni riguardo l'origine di una struttura conica circondata da materiale piroclastico, identificata dalle immagini acquisite dalla sonda MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging). Nel caso Marziano, invece, la simulazione numerica del cratere Firsoff, localizzato in Arabia Terra, ha permesso di capire quali siano i processi post-impatto che hanno determinato l'attuale morfologia del cratere e quale sia la struttura reologica caratterizzante quella regione. Dai risultati provenienti da entrambe le applicazioni emerge che la simulazione numerica dei crateri di impatto sia un importante e potente strumento per migliorare la conoscenza del Sistema Solare. Il secondo argomento è stato sviluppato dopo l'inserimento in orbita di Rosetta attorno alla cometa 67P. Diversi processi energetici, come la sublimazione, frammentazione, outburts e crolli gravitazionali, sono stati considerati al fine di spiegare la genesi dei massi cometari, che si trovano ovunque sulla superficie. Per uno studio dettagliato dell'argomento sono state utilizzate le immagini acquisite dagli strumenti OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) e CIVA (Comet Infrared and Visible Analyser), che sono le camere a bordo della sonda e del lander rispettivamente. I massi presenti sulle immagini sono stati analizzati quantitativamente, in termini di distribuzione in dimensioni, per comprendere quali siano i processi energetici che li generano e, in particolare, per determinare se tali processi avvengano ugualmente sulla cometa indipendentemente dalla scala spaziale considerata (m, cm, mm). A tale scopo, sono state ottenute le varie distribuzioni per i seguenti massi: (i) massi con un diametro maggiore di 7 m, (ii) massi con un diametro maggiore di 1 m (dall'analisi del sito Abydos, che è il luogo dove si suppone sia Philae) e (iii) grani (strutture su scala del mm-cm) presenti sulle immagini di CIVA. Nell'ambito della missione futura ESA/JUICE e del nostro forte coinvolgimento nella camera JANUS (Jovis, Amorum ac Natorum Undique Scrutator), l'ultimo tema affrontato è incentrato sul satellite ghiacciato Europa. La presenza di un oceano subsuperficiale all'interno di Europa è un argomento di primaria importanza e, in aggiunta, la recente osservazione del plume al polo sud tramite le osservazioni di HST, ha alimentato le domande riguardanti l'interazione tra la subsuperficie, la superficie e l'ambiente circostante. In questo contesto, il primo obiettivo è stato quello di generare una simulazione che rappresentasse un possibile deposito di un plume generato da fenomeni criovulcanici, in modo da definire in quali condizioni l'evento sarebbe osservabile da JANUS durante i flybys di Europa. Inoltre, dato che lo studio dei ``plume'' necessita di un'accurata caratterizzazione dell'esosfera, è stato realizzato un dettagliato calcolo dei tassi di perdita dell'esosfera di Europa in relazione ai processi di ionizzazione e dissociazione per impatto di elettroni, di scambio di carica e di fotoionizzazione.

L'analyse de la technique cassante met en evidence plusieurs regimes compressifs et distensifs depuis la periode tardi-hercynienne, et en particulier au tertiaire. Les accidents majeurs hercyniens de direction sud armoricaine (nw-se) structurent la region; ils regissent la fracturation tertiaire. La confrontation des donnees satellites hcmm et aeroportees aries, avec les observations de terrain montre que: -1) les images hcmm infrarouge thermique de nuit permettent de reconnaitre les structures majeures d'une region et sont un bon support a l'analyse regionale. -2) les donnees aries de haute resolution presentent un apport important a la cartographie de detail dans les zones a fort couvert vegetal

La problématique des espaces périurbains se trouve depuis une trentaine d'années au premier plan des réflexions sur les villes européennes. Leur caractérisation et leur comparaison focalisent les interrogations des chercheurs mais aussi des décideurs.<br />Cette thèse est centrée sur la question de l'identification des limites du périurbain et de sa structure spatiale, non pour tenter de le définir comme une catégorie de l'urbain, mais pour comprendre les processus en jeu dans cet espace périphérique. Elle développe une analyse comparative en intégrant les espaces périurbains de sept métropoles du sud-ouest de l'Europe (Barcelone, Lisbonne, Madrid, Porto, Bordeaux, Toulouse et Montpellier) et elle se fonde sur des observations renouvelées par l'utilisation de la télédétection. <br />Par la valorisation d'une nouvelle technique de lecture des images satellites et grâce à la précision permise par SPOT 5, la recherche précise les modalités des structurations spatiales et la nature des activités installées dans cette partie des villes, considérée jusqu'alors comme une périphérie essentiellement résidentielle. Elle met particulièrement en évidence le rôle de la distance au centre de la métropole et des grands axes routiers dans l'urbanisation de ces espaces. Elle montre également leur grande diversité.

Installée au cœur du quartier Latin, la station TCCON-Paris est le premier site du réseau TCCON exploité dans une mégapole européenne. TCCON est un réseau international de spectromètres FTIR qui surveillent l’abondance de gaz à effet de serre de l’atmosphère par spectroscopie d'absorption solaire directe. Le manuscrit décrit d'abord l'instrument FTS-Paris et la caractérisation de ses performances: détermination de la fonction d'appareil et étude de la stabilité de l'instrument par l'approche de variance Allan. Les résultats TCCON obtenus par GGG (code de transfert radiatif utilisé par le réseau TCCON) sont présentés, ainsi que les études réalisées pour améliorer la précision des mesures de la TCCON-Paris, notamment, l’étude des profils a prioiri de CO2 fournis par GGG (sans prendre en compte les émissions anthropogéniques) dans le cas de Paris. La méthode développée dans le cadre de ce doctorat s’appuie sur les conditions locales et réelles (mesures in situ et Lidar) pour modéliser des profils a priori de CO2 plus adaptés à Paris. Une description détaillée et illustrée est présentée, ainsi que l’étude de sensibilité de cette méthode et les corrections introduites. Le manuscrit termine sur l’utilisation de spectromètre mobiles FTIR à basse résolution (EM27/SUN) pour étudier l’inter-calibration des instruments entre les sites TCCON. Deux campagnes de mesures ont été réalisées pour caractériser les différences possibles entre les sites TCCON-Paris et TCCON-Orléans afin de transférer le standard WMO sur le site de Paris (survol d’avion interdit). Les résultats sont présentées et discutées<br>Total Carbon Column Observing Network (TCCON) is a global network of ground-based Fourier transform spectrometers which monitor column-averaged abundances (Xgas) of atmospheric gases by direct solar absorption spectroscopy. TCCON-Paris is the first European TCCON site operated in a megacity, located in the centre of Paris. The manuscript first describes the instrument and the characterisation of its performance. The instrumental line shape is investigated by using low-pressure HCl gas cell measurements. The instrument stability is determined by using the Allan variance approach. We have participated in a blind intercomparison test of measuring N2O gas columns in low-pressure cells. The results of our analysis have helped to identify an error in the référencé measurements. An overview of the GGG software package used by TCCON is given. Quality control procedure and biult-in filters are discussed. Different acquisition setups are compared in order to improve the precision of TCCON-Paris measurements. We investigate, as much CO2 a priori profiles provided by GGG are suited to retrieve CO2 abundances in Paris. From complementary CO2 in-situ and LIDAR measurements at the TCCON-Paris station, we construct improved CO2 a priori profiles that comply with the local ground conditions. An overview of the method and discussion of the sensitivity and biases of the retrieved XCO2 are given. Mobile, low-resolution instruments (EM27/SUN) used to allow the intercalibration of distant TCCON instruments. EM27/SUN was used as a transferable reference between the TCCON-Orleans and TCCON-Paris sites. Differences in retrieved XCO2 between EM27/SUN and TCCON are discussed