A survey of the literature on the techniques used in and the results obtained from studies of nightglow variability is presented. Three microprocessor controlled instruments (an eight channel tilting filter spectrometer, an earlier six channel version and a CCD based low light level camera) have been constructed with the aim of studying variations in the nightglow, especially of the type associated with the passage of gravity waves through the emitting layers. The final stages of development of the eight channel spectrometer are described, including the design of automatic dark count and reference light systems, a temperature control system for the filters and an interface for transferring the spectrometer data into a computer. Calibration experiments to determine the wavelength, line shape and intensity response of this spectrometer are described. The development of suites of computer programmes for analysing the data from both spectrometers and the camera is then discussed. For the spectrometers, these perform the functions of subtraction of dark count, reduction of the calibration data to a form suitable for use in the analysis of data spectra in terms of a set of line shapes and continuum response functions, and execution of this analysis to produce plots of the emission intensities and OH rotational temperature versus time. For the camera, software was produced to allow separation of stellar images from the airglow emission; stellar image intensities were analysed in an attempt to characterise atmospheric absorption. Software was also written to correct airglow intensities for absorption and the van Rhijn effect and finally to reproject the images in the form of a map of the emitting layer. Observations made with the instruments working separately and in conjunction are described and the results are presented as an example of the performance of the instruments and the software.

This thesis deals with the development of a microprocessor controlled CCD based camera for digital imaging of the nightglow. A brief description of the techniques used to image the nightglow is given and the reasons for choosing a CCD as the detector are discussed. The fundamentals of CCD operation are then described with particular emphasis on buried channel CCD image sensors as the P8603 CCD used in the camera is of this type. A major part of the thesis is devoted to the detailed design of the camera electronics which consists of three main sections; (i) a MC6802 based microprocessor controller with 4 K of ROM and 64 K of dynamic RAM; (ii) a display interface which allows an on-line display of the images to be produced on an oscilloscope for monitoring purposes while observing; and (iii) the CCD interface which consists of the drive pulse buffers for the image, store and readout sections of the CCD, the bias voltage generators for the CCD on-chip charge amplifier, and the signal processing electronics which has a choice of four software selectable gains and uses correlated double sampling to achieve low noise levels. The design of a digital cassette system for recording the image data is also described. The system, which is based on a low cost stereo cassette recorder, accepts and produces data in the same RS232 serial format used by the camera and is capable of operating at up to 9600 baud on two channels. A further section deals with the optical, structural and cryogenic design. This includes a description of the camera optical system which is based on a commercial FI.4 CCTV lens, theoretical calculations of the expected response of the camera to a range of nightglow emissions, the design of the liquid nitrogen cryostat which is used to cool the CCD, the design of the camera chassis, and calculations to determine (i) the CCD temperature required to reduce the dark current to an acceptable level; and (ii) the capacity of the liquid nitrogen reservoir which is necessary to allow a whole night's observing without refilling. The detailed operation of the camera control program, which is written in 6800 assembly language, is then described with the aid of flowcharts. Currently the control program is set up to give a one minute integration period using half-frame imaging and a 3 x 2 pixel amalgamation. The final section of the thesis deals with the testing and performance of the camera. Several experiments were carried out including the measurement of the various possible ampilifier gains, the noise performance of the system, the angular response of the camera optics, and the calibration of the camera using a standard light to allow the absolute intensity of nightglow emissions to be calculated. Theoretical calculations of the expected noise levels and the expected response of the camera to the standard light are also included. A suite of image processing programs, written in Pascal for an Apple II microcomputer, are then described. These programs allow various operations to be performed such as scanning the images stored on tape, and correcting for the defective columns on the CCD and the angular response of the camera optics. Lastly, the performance of the camera in the field is discussed and the results of observations made locally, which include photographs of images believed to show hydroxyl airglow structure, are presented.

Les émissions ultraviolettes des atmosphères de Vénus et de Mars, couramment appelées airglows, sont des phénomènes lumineux qui proviennent de relaxations d'atomes et de molécules passant d'un état excité à un état d'énergie inférieure. Ceux-ci nous renseignent sur les densités des constituants intervenant dans les réactions chimiques des atmosphères, ainsi que sur la dynamique des mésosphères respectives. Cette thèse traite de l'analyse détaillée de ces phénomènes dont le signal a été détecté entre 118 et 320 nm par les instruments SPICAV et SPICAM à bord des satellites Venus Express et Mars Express. Afin de bien comprendre le sujet abordé, les deux planètes, les différents airglows analysés et les instruments sont abordés dans une introduction constituant le premier chapitre de ce travail. Le chapitre 2 est consacré aux outils numériques qui servent à l'analyse et à la modélisation des airglows. Les trois chapitres suivants sont dédiés à leur caractérisation en intensité, à leur répartition en altitude et à leur localisation statistique. En particulier, nous étudions dans le chapitre 3 l'airglow de la molécule NO présent dans l'atmosphère nocturne de Mars à l'aide des données provenant de l'instrument SPICAM. Dans ce chapitre, nous utilisons un modèle chimique et diffusif unidimensionnel afin de confronter la théorie aux observations. Dans le chapitre 4, la même émission provenant de l'atmosphère de Vénus est analysée à l'aide du modèle unidimensionnel et des données enregistrées par l'instrument SPICAV. Les émissions de CO Cameron et du doublet CO2+ de l'atmosphère éclairée de Mars sont abordées dans le chapitre 5 à l'aide des données SPICAM. Ces émissions sont également comparées à un modèle stochastique afin de quantifier leurs processus de formation. Le chapitre 6 expose quelques perspectives de travail qui concernent ces phénomènes et qui permettrons à l'avenir d'acquérir de nouvelles informations à partir des données récoltées par SPICAV et SPICAM. Finalement, nous concluons en rassemblant les résultats clés des trois chapitres formant le corps principal de cette thèse.

Le rayonnement atmosphérique appelé nightglow est un phénomène se produisant à haute altitude (environ 90 km). Il consiste en l’émission d’un rayonnement suite à la désexcitation de certaines molécules et atomes (OH, Na, O2 et O). Il se répartit sur une large gamme spectrale, en particulier dans l’infrarouge et se propage jusqu’au niveau du sol. Le rayonnement nightglow constitue un marqueur important pour la haute atmosphère, permettant de remonter à la température, mais également à de nombreux phénomènes dynamiques comme les marées atmosphériques ou les ondes de gravité. Sa propagation au niveau du sol permet l’éclairage de scène terrestre et ainsi la vision nocturne à l’aide de caméras proche infrarouge. Afin de mieux connaître les fluctuations de ces émissions en fonction du temps à différentes échelles et en différents lieux sur la planète, la thèse s’est axée sur une étude observationnelle et une étude théorique. L’étude observationnelle a produit une climatologie à grande échelle par l’extraction du rayonnement issu des données de l’instrument GOMOS. Les campagnes de mesures réalisées au sol ont quant à elles mis en avant certains aspects dynamiques importants comme les marées et les ondes de gravité. Pour reproduire le rayonnement nightglow, il a été nécessaire de modéliser les réactions chimiques des nombreuses espèces présentes à haute altitude, le chauffage, la photodissociation de certaines molécules par le rayonnement solaire et la propagation du rayonnement vers le sol. Certains processus dynamiques ont été inclus comme la diffusion moléculaire, la diffusion turbulente et une paramétrisation des marées. Enfin, les résultats du modèle sont comparés aux observations satellitaires ainsi qu’au niveau du sol et des tests de sensibilité sont effectués pour estimer la réponse du rayonnement aux différents modules du modèle. / The nightglow is an atmospheric radiation which occurs at high altitude (around 90 km). It comes from the desexcitation of specific molecules and atoms (OH, Na, O2 and O). It spreads over a wide spectral band, especially in the infrared and propagates to the ground level. The nightglow emission is an important mark for the high atmosphere, as it allows the retrieval of the temperature and many dynamic processes such as atmospheric tides or gravity waves. Its propagation to the ground level allows the illumination of terrestrial scene and therefore the night vision with the use of near infrared cameras. In order to have a better knowledge of the emission fluctuations as a function of time for various scales and at various locations, the work is focused on an observational and theoretical study. The observational study produced large scale climatology with the extraction of nightglow emission from GOMOS data. On the other hand, ground measurements highlighted some dynamical aspects such as tides and gravity waves. To model the nightglow emission, it has been necessary to take into account the chemical reactions of the species available at high altitude, the heating, the photodissociation process and the propagation of the emission to the ground. Selected dynamical processes have been included, such as the molecular and turbulent diffusion, and a tide parameterization. Finally, the results of the model are compared to the satellite and ground observations and sensitivity tests are run to estimate the response of the emission to the various modules of the model.

The Earth's mesosphere and lower thermosphere in the altitude range 50-130 km is a fascinating part of our atmosphere. Complex interactions between radiative, dynamical, microphysical and chemical processes give rise to several prominent phenomena, many of those centred around the mesopause region (80-100 km). These phenomena include noctilucent clouds, polar mesosphere summer echoes, the ablation and transformation of meteoric material, and the Earth’s airglow. Strong stratification and small scale interactions are common features of both these phenomena and the mesopause region in general. In order to study interactions on the relevant spatial scales, in situ measurements from sounding rockets are essential for mesospheric research. This thesis presents new measurement techniques and analysis methods for sounding rockets, thus helping to improve our understanding of this remote part of the atmosphere. Considering the need to perform measurements at typical rocket speeds of 1 km/s, particular challenges arise both from the design of selective, sensitive, well-calibrated instruments and from perturbations due to aerodynamic influences. This thesis includes a quantitative aerodynamic analysis of impact and sampling techniques for meteoric particles, revealing a distinct size discrimination due to the particle flow. Optical techniques are investigated for mesospheric ice particle populations, resulting in instrument concepts for accessing smaller particles based on Mie scattering at short ultraviolet wavelengths. Rocket-borne resonance fluorescence measurements of atomic oxygen are critically re-assessed, leading to new calibration concepts based on photometry of O2 airglow emissions. The work presented here also provides important pre-studies for the upcoming PHOCUS rocket campaign from Esrange in July 2010. PHOCUS will address the interaction between three major mesospheric players: meteoric smoke, noctilucent clouds and gas-phase chemistry.

The purpose of this study is two-fold. The first is to determine the dependence of the molecular ion profiles on the various ionospheric and atmospheric parameters that affect their distributions. The second is to demonstrate the correlation of specific ionospheric parameters with 6300 Å nightglow intensity during periods of magnetically quiet and disturbed conditions.

Nous retraçons la vie et le parcours professionnel de Jean Dufay, et ce fil directeur permet d'étudier en même temps le développement des observations et des recherches astrophysiques dans les Observatoires de Lyon et de Haute-Provence. Jean Dufay nait à Blois en 1896. Après son engagement militaire pendant la première guerre mondiale, il entre à l'ENS et obtient l'agrégation de physique en 1921. Il enseigne pendant sept ans dans des lycées, tout en préparant une thèse de doctorat, qu'il soutient en 1928 : Recherches sur la lumière du ciel nocturne.Il choisit alors une nouvelle carrière et entre en 1929 à l'Observatoire de Lyon, comme aide-astronome. Il devient directeur de l'établissement en 1933 et oriente son équipe vers des recherches d'astrophysique stellaire. D'autre part, Jean Dufay fait partie dès 1932 de la commission ministérielle qui étudie la création d'un observatoire d'astrophysique. Il est nommé en 1937 directeur de ce futur établissement, qui deviendra l'Observatoire de Haute-Provence (OHP). Tout en gardant la direction de l'Observatoire de Lyon, il coordonne la construction et l'équipement de l'OHP, qui devient en 1959 l'un des plus modernes d'Europe avec un télescope de 193 cm associé à un grand spectrographe.Jean Dufay dirige les deux observatoires jusqu'à sa retraite en 1966, tout en enseignant à la Faculté des Sciences et en continuant ses recherches astrophysiques. Il publie de nombreux articles et plusieurs livres. Il préside une commission de l'UAI. Il acquiert une notoriété certaine dans la communauté scientifique internationale de son époque.Jean Dufay est l'un des acteurs du renouveau de l'astronomie en France, dans le deuxième tiers du XXe siècle. À son arrivée à Lyon, l'observatoire travaille surtout pour l'astronomie de position, avec des méthodes qui n'ont pas changé depuis 1880. En moins de dix ans, ce type de recherche est abandonné, et remplacé par la photométrie de précision et la spectrophotométrie. Après la seconde guerre mondiale, les pratiques de l'astrophysique sont définitivement intégrées à l'Observatoire de Lyon, qui travaille alors en synergie avec l'OHP / We trace the life and career of Jean Dufay, and at the same time, this allows us to study the development of observations and astrophysical research in the Lyon and Haute-Provence Observatories.Jean Dufay was born in Blois in 1896. After his military involvement in the First World War, he joined the ENS and passed the agrégation in physics in 1921. He taught for seven years in high schools, while preparing a PhD thesis, presented in 1928 : Research on Light in the Night Sky.He then chose a new career and entered the Lyon Observatory in 1929, as an assistant astronomer. He became director of the institution in 1933 and directed his team’s work towards research in stellar astrophysics. Besides, in 1932, Jean Dufay joined the ministerial commission studying the creation of an astrophysics observatory. In 1937 he was appointed director of this future institution, which would later become the Haute-Provence Observatory (OHP). While keeping his post of manager of the Lyon Observatory, he coordinated the construction and equipment of the OHP, which in 1959 became one of the most modern ones in Europe, with a 193 cm telescope associated with a large spectrograph.Jean Dufay was at the helm of the two observatories until his retirement in 1966, while teaching at the Faculty of Sciences and keeping up his astrophysical research. He published numerous articles and several books. He chaired a commission of the IAU, and gained genuine recognition in the international scientific community of his time.Jean Dufay was one of the actors of the renewal of astronomy in France, in the second third of the twentieth century. When he arrived in Lyon, the observatory mainly worked for positional astronomy, with methods that had been unchanged since 1880. In less than ten years, this kind of research fell into disuse and was replaced by precision photometry and spectrophotometry. After the Second World War, astrophysical practices were integrated for good into Lyon Observatory, which then works in synergy with OHP