Connaitre précisément la structure interne des corps célestes est indispensable pour, à la fois, comprendre la physique qui régit leur existence et le processus qui leur a donné naissance. La sismologie, d’abord appliquée à la Terre puis au soleil, s’est révélée être un outil très efficace pour sonder leurs intérieurs. Dans les années 70 (Vorontsov et al 1976), des premiers travaux théoriques ont étudié la possibilité d’une sismologie des planètes géantes gazeuses. Les premières tentatives de mesures d’oscillations ont eu lieu à la fin des années 80. La détection des modes d’oscillations de Jupiter s’est avérée une entreprise très délicate en raison de sa rotation rapide. Pour augmenter les chances de détection, un instrument spécifique a été construit au début des années 2000 à l’OCA. Cet instrument, appelé SYMPA, est un spectromètre imageur de type Mach-Zehnder capable de produire une carte de vitesse radiale de Jupiter. Une détection de modes d’oscillations sur Jupiter par cet instrument a été publiée par Gaulme et al en 2011. Une version améliorée de l’instrument (appelé DSI) a été proposée pour la mission spatiale JUICE à destination de Jupiter, et un nouveau prototype a été construit dans ce but. Par la suite, le projet s’est réorienté vers un programme d’observation depuis le sol sous la forme d’un réseau de trois télescopes répartis en longitude (USA, France, Japon) et financé par l’ANR à partir de 2015 (ANR JOVIAL). L’intérêt de la mise en réseau est d’assurer la continuité des données (météo mise à part). L’instrument étant capable de produire des cartes de vitesse radiales, le projet permet également l’étude de la dynamique atmosphérique des planètes géantes. Ce travail de thèse s’inscrit dans le contexte de préparation de JOVIAL, avec pour objectif de caractériser l’instrument en laboratoire et d’identifier les problèmes liés aux conditions réelles d’observation. Les mesures en laboratoires ont montré des performances conformes aux attentes, avec un bruit de mesure propre à l’instrument inférieur au bruit de photon attendu sur Jupiter. Les premières mesures sur le ciel avec un télescope ont mis en évidence une sensibilité de l’instrument au degré de polarisation de la lumière ainsi qu’une dérive de la vitesse mesurée liée aux instabilités de position de la pupille pendant les observations. Le design de l’instrument et de son interface avec le télescope a été revu pour résoudre ces problèmes. Plusieurs campagnes d’observations de Jupiter ont été réalisées, permettant de mettre sur pied une chaine complète de traitement des données, dont la validité a été vérifiée par des simulations réalistes. Les observations de Jupiter ont donné des résultats scientifiques particulièrement intéressants. L’analyse des données de deux campagnes de 2015 et 2016 a fourni des séquences temporelles de cartes de vitesses radiales de Jupiter. Une première étude a consisté à chercher dans ces cartes la signature des vents zonaux et de les comparer aux mesures réalisées par suivi des nuages sur des images résolues (cloud-tracking). Une telle mesure n’avait jamais été faite par effet Doppler. Le résultat, bien qu’affecté par des biais de mesures identifiés, montre des profils de vents stables d’une année sur l’autre et en cohérence avec les valeurs issues du cloud-tracking, sauf au niveau de la partie nord de la bande équatoriale de Jupiter. La mesure Doppler suggère en effet une vitesse de vent bien inférieure à la vitesse apparente dans cette zone, ce qui a potentiellement des implications sur les modèles de dynamique atmosphérique. Ces résultats sont très importants pour mieux comprendre les mesures de la sonde Juno, actuellement en orbite autour de Jupiter. L’analyse fréquentielle des données temporelles a été abordée en fin de thèse. Les analyses préliminaires ne semblent pas pour l’instant reproduire la détection de SYMPA. Une analyse plus poussée est nécessaire avant de conclure à une absence du signal. / To know precisely the internal structure of the celestial bodies is essential to both to understand the physics which governs their existence, and the process which gave them birth. First applied to the Earth and then to the sun, seismology has proven to be a very effective tool to sound their interiors. It has become natural and legitimate to question the possibility of seismology of gaseous giant planets. The first theoretical work was carried out in the 1970s (Vorontsov et al. 1976), and the first attempts to measure oscillations at the end of the 1980s. The detection of Jupiter's oscillating modes turned out to be very difficult (reduced flux, small apparent diameter, fast rotation ...). To increase the chances of detection, a specific instrument was built in the early 2000s at the OCA. This instrument, called SYMPA, is a Mach-Zehnder-type imaging spectrometer enable to produce radial velocity maps of Jupiter. A first detection of acoustic modes on Jupiter with this instrument was published by Gaulme et al in 2011. An improved version of the instrument (called DSI), based on the same principle, was built in the wake, with the primary objective of boarding a spacecraft to Jupiter. The project was finally reoriented towards an observation program from the ground in the form of a network of three telescopes equidistant in longitude (USA, France, Japan) and supported by the ANR fund starting in 2015 (ANR JOVIAL). The interest of the network is to ensure the continuity of data (weather apart). The instrument being able to produce radial velocity maps, the project also aims to study the atmospheric dynamics of giant planets. This thesis work is part of a preparation for JOVIAL, with the aim of characterizing the instrument and identifying the problems related to real observations conditions. Laboratory measurements showed expected performances with an instrumental noise level (related to thermal fluctuations) lower than expected photon noise on Jupiter. The first measurements on the sky with a telescope showed a sensitivity of the instrument to the degree of polarization of the light as well as drifts of the velocity measurements due the motions of the pupil position. Some adjustments of the design of the instrument and its interface with the telescope were necessary to solve these issues. Several Jupiter observation campaigns were carried out during the thesis, allowing the development of full data processing software. The complete procedure was tested against simulated data and validated. Two observations runs in 2015 and 2016 were analyzed to produce time sequences of radial velocity maps of Jupiter, providing very interesting scientific results. First, the maps were analyzed to look for the signature of the zonal winds and to compare them with the measurements made by cloud-tracking. Such measurements by Doppler effect were never made before. The result, albeit affected by measurement biases, showed stable year-to-year wind patterns and coherent results with cloud-tracking measurements, except at the northern part of the Jovian’s equatorial band. The Doppler measurement indeed suggests a wind speed well below the apparent speed in this area, which potentially has implications for the theory of atmospheric dynamics and will be helpful to interpret the Juno (a spacecraft presently orbiting Jupiter) measurements. Frequency analysis of temporal data was undertaken at the end of the thesis. The preliminary results do not seem for the moment to reproduce the SYMPA detection. Further analysis is necessary before concluding if the signal is absent or attenuated.

Equatorial plasma bubbles (EPBs) are large structures consisting of depleted plasma that generally form on the nightside of Earth's ionosphere along magnetic field lines in the upper thermosphere/ionosphere. While referred to as `bubbles', EPBs tend to be longer along magnetic latitudes and narrower along magnetic longitudes which are on the order of thousands and hundreds of kilometers, respectively. EPBs are a well documented occurrence with observations spanning many decades. As such, much is known about their general behavior, seasonal variation of occurrences, increasing/decreasing occurrences with increasing/decreasing solar activity, and their ability to interact and interfere with radio waves such as GPS. This dissertation expands on this understanding by focusing on the detection and tracking of EPBs in the upper thermosphere/ionosphere along equatorial to low latitudes. To do this, far ultraviolet (FUV) emission observations of the recombination of O$^+$ with electrons via the Global-Scale Observations of the Limb and Disk (GOLD) mission are analyzed. GOLD provides consistent data from geostationary orbit with the eastern region of the Americas, Atlantic, and western Africa. The optical data can be used to pick out gradients in brightness along the 135.6 nm wavelength which correlate with the location of EPBs in the nightside ionosphere. The dissertation provides a novel method to look at and analyze 2-dimensional data with inconsistent time-steps for EPB detection and tracking. During development, preprocessing of large scale (multiple years) data proved to be the largest time sync. To that end, this dissertation tests the possibility of using convolution neural networks for detection of EPBs with the end goal of reducing the amount of preprocessing necessary. Further, data from the Ionospheric Connection Explorer's (ICON's) ion velocity meter (IVM) are compared to EPBs detected via GOLD to understand how the ambient plasma around the EPBs behave. Along with the ambient plasma, zonal and meridional thermospheric winds observed by ICON's Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument are analyzed in conjunction with the same EPBs to understand how winds coincident with EPBs behave. An analysis of winds before EPBs form is also done to observe the potential for both zonal and meridional winds' ability to suppress and amplify EPB formation. / Doctor of Philosophy / Equatorial plasma bubbles (EPBs) are large structures that generally form during post- sunset along Earth's magnetic equator. While referred to as `bubbles', EPBs tend to be thousands of kilometers from north to south and hundreds of kilometers from east to west and well over a thousands kilometers in altitude. EPBs are a well documented occurrence with observations spanning many decades. This includes their ability to interfere with radar and GPS. This dissertation expands on the scientific community's understanding by focusing on the detection and tracking of EPBs along the magnetic equator. To do this, observations from the NASA Global-Scale Observations of the Limb and Disk (GOLD) mission are analyzed. GOLD provides consistent observations looking over the eastern region of the Americas, Atlantic, and western Africa. A unique method to look at and analyze this data for EPB detection and tracking is developed. This dissertation also tests the possibility of using machine learning for detection of EPBs. Further, data from the NASA Ionospheric Connection Explorer (ICON) mission is compared to EPBs detected via GOLD to understand how the behavior of the upper atmosphere and the conductive region therein, known as the ionosphere, interact with the EBPs themselves.