The Interplanetary Magnetic Field (IMF) has a controlling effect on the Magnetosphere and Ionosphere. The objective in this work is to investigate the probable effects of IMF on Ionospheric and Geomagnetic response. To fulfill the objective the concept of an event has been created based on the polarity reversals and rate of change of the interplanetary magnetic field components, Bz and By. Superposed Epoch Method (SPE) was employed with the three event definitions, which are based on IMF Bz southward turnings ranging from 6 to 11 nT in order to quantify the effects of IMF By and Bz. For the first event only IMF Bz turnings were taken into account while for the remaining, positive and negative polarity for IMF By were added. Results showed that the increase in the magnitude of IMF Bz turnings increased the drop of F layer critical frequency, f0F2. The drop was almost linear with the increase in magnitude of polarity reversals. Reversals with a positive IMF By has resulted in the continuation of geomagnetic activity more than 4 days, that is to say, the energy, that has penetrated as a consequence of reversal with a positive By polarity, was stored in outer Magnetosphere,whereas, with a negative IMF By the energy was consumed in a small time scale. At the second step of the work, although conclusions about geomagnetic activity could be done, as a consequence of data gaps for f0F2 in addition to having low numbers of events, characterization of f0F2 due to constant IMF By polarity could not be accomplished. Thus, a modeling attempt for the characterization of the response due to polarity reversals of IMF components with the Genetic Programming was carried out. Four models were constructed for different polarity reversal cases and they were used as the components of one general unique model. The model is designed in such a way that given 3 consecutive value of f0F2, IMF By and IMF Bz, the model can forecast one hour ahead value of f0F2. The overall model, GETY-IYON was successful at a normalized error of 7.3%.

viii Title: Dynamics of the bow shock and magnetopause Author: Karel Jelínek Department: Department of Surface and Plasma Science Supervisor: Prof. RNDr. Zdeněk Němeček, DrSc. Department of Surface and Plasma Science e-mail address: zdenek.nemecek@mff.cuni.cz Abstract: The interplanetary space is a unique laboratory which allows us to dis- cover (i) a behavior of the plasma under different conditions, (ii) origin of its insta- bilities, and (iii) its interaction with obstacles such as the Earth's magnetosphere. The present thesis analyzes the outer Earth's magnetosphere. The results are based on the in situ sensing by a variety of the spacecraft (e.g., IMP-8, INTERBALL-1, MAGION-4, Geotail, Cluster-II and Themis). The solar wind curently monitored by the WIND and ACE spacecraft near the La- grange point L1 affects by its dynamic pressure the Earth's magnetic field which acts as a counter-pressure and the boundary where these pressures are balanced is the magnetopause. Due to supersonic solar wind speed, the bow shock forms in front of the magnetopause and a region in between, where plasma flows around an obstacle is named the magnetosheath. The thesis contributes to a deaper understanding of the dependence of magnetopause and bow shock shapes and positions, especially, (1) on the orientation of the inter-...

Electromagnetic wave phenomena represent a crucial factor during the forma- tion of the Earth's magnetosphere, as they are responsible for the energy trans- fer in the collisionless plasma medium. Multipoint observations of such wave phenomena are particularly useful to distinguish between spatial and temporal intensity variations. Moreover, an approximate event spatial extent and prop- agation directions can be determined. The thesis is focused on the statistical study of conjugate observations of wave phenomena called quasiperiodic (QP) emissions observed by the Van Allen Probes spacecraft and ground-based Kan- nuslehto station. Altogether, 26 simultaneously observed events were analyzed. This approach is unique in the sense that most such analyses up to date were only case studies. The thesis further presents the analysis of the dependence of properties of another wave phenomena, called magnetospheric line radiation (MLR), on the geomagnetic activity indices and solar wind parameters. Geomag- netic activity effects on the event characteristics are revealed. Finally, the effect of interplanetary shocks on the overall very low frequency (VLF) wave intensity measured by the DEMETER spacecraft is studied.

This project aims to investigate the orientation of plasma jet fronts in Earth's magnetotail using multi-spacecraft measurement data. The orientations are estimated by applying minimum variance analysis (MVA) and multi-spacecraft timing analysis for finding normal vectors to the jet fronts as they pass over the spacecraft. An agreement between the two analysis methods is found when applied to a data set of fronts. The obtained results are compared to measurements of the ion bulk velocities of the fronts, where a discrepancy is found. Limitations of the analysis are addressed and alternative approaches are presented. / I detta projekt undersöks riktningen hos fronter till plasma-jetstrålar i jordens magnetsvans genom analysering av mätdata från en samling rymdfarkoster. Riktningarna uppskattas genom att applicera minimum variance analysis (MVA) samt multi-spacecraft timing för att hitta normalvektorer till fronterna som passerar rymdfarkosterna. De två metoderna uppnår liknande resultat när de tillämpas på en uppsättning fronter. De erhållna normalvektorerna jämförs även med riktningen av uppmätta jonhastigheter från rymdfarkosterna där en tydlig skillnad förekommer. Begränsningar av analysmetoden påpekas och förslag på alternativa tillvägagångssätt läggs fram.

Data visualization is a field dedicated to effectively showing large amounts of collected data. A field where data visualization has shown promising results in its ways to effectively answer questions is the fundamental research of the universe. This thesis describes how to visualize the Earth’s magnetosphere as it interacts with the solar wind, using numerical methods, semi-transparent surfaces, and contours in OpenSpace. A magnetosphere module was implemented into OpenSpace, and the OpenSpace GUI was extended to give the user a possibility to interact with the visualization. The implemented algorithm in the magnetosphere module was measured in terms of speed, robustness, and user understanding. The implementation made it possible to visualize a simple model of the Earth’s magnetosphere, both when it interacts and when it does not interact with the solar wind. The measured speed showed a trend of a linear increase when more magnetic field lines were added to the visualization, where the run time was low for all tests. The algorithm was shown to be robust in its creation of the magnetosphere. When asked about what the users thought of the implemented visualization, a majority were positive and thought it to be a good complement to learning about the Earth’s magnetosphere. For a realistic model, there is a possibility that the speed and robustness may get worse, but the results are good for a simple model. To make the visualization itself more informative, more highlights are needed for important parts of the structure, as well as different colors that differ on which surfaces belong to which geographical pole. / Creative Exploration of the Atmosphere

The magnetopause is an important feature in near-Earth space, where the continuously emitted solar wind from the sun meets the magnetic field of the Earth. This boundary region between the so-called magnetosheath on the outside and magnetosphere on the inside is a constantly back-and-forth moving discontinuity upheld by a pressure balance on both sides, upon which an important process in mass and energy transportation through the universe called magnetic reconnection occurs. To gain further understanding about the magnetopause, this study aimed to produce additional statistical scientific material concerning the discontinuity, including the total pressure difference across it, pressure values and total pressure contributions in the magnetosheath and magnetosphere bordering it, and velocity of the magnetopause related to pressure difference. This was done by analysing data from the MMS-project during crossings of the magnetopause in late 2017 and throughout 2018 at the subsolar point and dawn-/dusk flanks. While the results show in general good agreement with previous studies, some intriguing features were noted, including a pressure difference bias towards higher mean total pressures in the magnetosheath in all regions, as well as shift in dominating pressure in the magnetosphere from magnetic pressure at the subsolar point to thermal pressure on the flanks. Further study to confirm these features ought to be conducted. Finally, no clear connection was revealed between magnetopause velocity and pressure imbalance. / Magnetopausen är en viktig struktur i den jordnära rymden, där den ständigt utskickade solvinden från solen möter jordens magnetfält. Detta gränsområde mellan det så kallade magnetosheath på utsidan och magnetosfären på insidan är en diskontinuitet i ständig rörelse fram och tillbaka, upprätthållen av en tryckbalans på båda sidor, på vars yta en mycket viktig process för mass- och energitransport i universum sker kallad magnetisk rekonnektion. För att öka förståelsen för magnetopausen, har denna studie haft som mål att skapa ytterligare statistiskt material gällande diskontinuiteten. Detta inkluderar den totala tryckskillnaden över den, tryckvärden och deras bidrag till det totala trycket i magnetosheath och magnetosfären som gränsar den, samt magnetosfärens hastighet kopplat till tryckskillnaden över den. Detta gjordes genom analys av data från MMS-projektet, specifikt korsningar av magnetopausen i slutet av 2017 och under 2018 vid subsolar point och morgon- /kvällsflankerna. Om än resultaten visar på generellt sätt god överensstämmelse med tidigare studier, noterades en del intressanta resultat. Främst av dessa var en tydlig tendens för högre totalt tryck i magnetosheath jämfört med magnetosfären i alla undersökta regioner, samt ett oväntat skifte av dominerande tryck i magnetosfären från magnetiskt tryck vid subsolar point till termiskt tryck vid flankerna. Fortsatta studier för att bekräfta dessa resultat bör genomföras. Gällande magnetopaushastighet kopplat till tryckskillnad kunde ingen klar koppling ses från resultaten.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Les ceintures de radiation correspondent à la région de la magnétosphère dans laquelle se trouvent les particules de hautes énergies. Le couplage entre le vent solaire et la magnétosphère donne lieu à des variations des flux de particules sur plusieurs ordres de grandeurs. L’objectif de cette thèse est d’observer et caractériser ces variations de flux d’électrons au passage de différents types d’événements tels que les régions d’interaction en co-rotation (CIRs) et les éjections de masse coronale interplanétaires (ICMEs). Pour cela, nous avons traité et analysé les données de plusieurs types: paramètres du vent solaire, indices géomagnétiques et flux d’électrons dans les ceintures de radiation. Dans les trois premiers chapitres, nous rendons compte de la complexité de l’environnement spatial Terrestre et présentons les différentes données utilisées. Les travaux de thèse sont ensuite organisés en quatre chapitres. Premièrement, nous utilisons les mesures des satellites NOAA-POES afin de caractériser les flux d’électrons dans les ceintures. Nous étudions ensuite les différences de variations de flux causées par les CIRs et les ICMEs en fonction de l’énergie des électrons et du paramètre L*. Après avoir montré le fort lien entre les intensités d’orages magnétiques et les variations de flux, nous nous focalisons sur les ICMEs et la variabilité des orages qu’elles causent. Enfin, nous insistons sur l’importance des enchaînements d’événements. Après avoir quantifié la forte tendance qu’ont les ICMEs à former des séquences, nous réalisons une étude statistique sur les orages qu’elles causent, puis trois études de cas afin d’illustrer leurs effets sur les ceintures. / The radiation belts are the toroidal region within the inner magnetosphere where high energetic particles are located. The coupling between the solar wind and the magnetosphere leads to strong variations of particle fluxes that can therefore increase or decrease over several orders of magnitude. The aim of this thesis is to observe and characterize the variations of fluxes during the crossing of several types of events originating from the sun such as Corotating Interaction Regions (CIRs) and Interplanetary Coronal Mass Ejections (ICMEs). To do so, we processed and analyzed the data of various types : solar wind parameters, geomagnetic indices, and electron fluxes within the radiation belts. In the three first chapters, we report on the complexity of the Terrestrial space environment and we present the Solar-Terrestrial system and the data used. Then, our work is organized around four chapters. First, we characterized the electron fluxes within the radiation belts as measured by the NOAA-POES spacecrafts. Then, we studied the difference between the variations of fluxes caused by the CIRs and the ICMEs depending on the energy and the L* parameter. After establishing strong links between the intensity of magnetic storms and the variations of fluxes, we focused on the ICMEs and the variability of the related magnetic storms. Eventually, we emphasized the importance of the sequences of events. After quantifying the trend of the ICMEs to form sequences, we performed a statistical study on the magnetic storms caused by such sequences. Finally three study cases were performed in order to illustrate the various possible effects on the radiation belts.

Les ceintures de radiation de la planète géante Jupiter sont constituées d’électrons, de protons et d’ions lourds de très haute énergie. Ces particules chargées représentent un risque majeur pour les satellites artificiels cherchant à explorer Jupiter. Dans le même temps, comprendre l’origine et la répartition de ces particules est une problématique fondamentale du domaine de la Physique de l’Espace.Le modèle physique Salammbô de l’ONERA répond aux deux enjeux précédents. Il a été développé pour le cas de la planète géante au cours de deux thèses successives qui se sont terminées en 2004 [Santos-Costa, 2001 ; Sicard, 2004]. Les travaux précédents ont permis de mettre en place un modèle d’électron qui s’étend de l’atmosphère de Jupiter jusqu’à l’orbite d’Europe (9 Rj) et un modèle de proton jusqu’à l’orbite de la lune volcanique Io (6 Rj). Depuis cette date, la mission américaine Galileo, qui fut en orbite autour de Jupiter jusqu’en 2003, a livré de nombreuses informations sur les ceintures de radiation et sur l’environnement qui influence celles-ci.Cette thèse revisite le modèle électron et étend le modèle proton jusqu’à l’orbite d’Europe. Cela permet, en particulier, de montrer que les ondes électromagnétiques se propageant entre les orbites des lunes Io et Europe induisent des pertes significatives de particules, celles-ci étant précipitées dans l’atmosphère de Jupiter. Les modèles proposés au cours de cette thèse sont également mieux à même de prédire l’environnement extrême et limitant des ceintures de radiation que les précédents travaux. / The radiation belts of the giant planet Jupiter are populated by very energetic electrons, protons and heavy ions. On one hand, these charged particles represent a major threat to exploration missions. On the other hand, understanding the radiation belt particles origin and distribution is a fundamental question of the broad Space Physics research domain.The physical model Salammbô of ONERA addresses the two previous challenges. It has been developed during two successive previous PhD thesis that ended in 2004 [Santos-Costa, 2001; Sicard, 2004]. Previous work has enabled to predict and study the electrons inward of Europa’s orbit (9 Rj) and the protons inward of the volcanic moon Io (6 Rj). Since 2004, the Galileo mission that was in orbit around Jupiter until 2003 has provided many inputs regarding the Jovian radiation belts and the environment that shape them.This PhD thesis revisits the electron model and expands the proton’s one up to Europa’s orbit. Our modeling effort shows that, in particular, electromagnetic waves propagating between the orbits of the moons Io and Europa create strong particle losses within the radiation belts, as the charged particles are precipitated in the Jovian atmosphere. In addition, our models are better suited than what has been proposed by previous work to predict the harsh radiative environment near Jupiter.STAR

<p>This thesis deals with the development and calibrations of sensors to measure energetic neutral atoms (ENAs) at Mars, Venus, and the Earth. ENAs are formed in charge exchange processes between energetic, singly--charged ions and a cold neutral gas. Since ENAs can travel in long straight trajectories, unaffected by electric or magnetic fields, they can be used to remotely image plasma interactions with neutral atmospheres. ENA instrument techniques have matured over the last decade and ENA images of the Earth's ring current for example, have successfully been analyzed to extract ion distributions and characterize plasma flows and currents in the inner magnetosphere.</p><p>Three different ENA sensors have been developed to image ENAs at Mars, Venus, and the Earth. Two of them, the nearly identical Neutral Particle imagers (NPIs) are on-board the Mars Express and Venus Express spacecraft as a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3 and 4) instruments. The third is the Neutral Atom Detector Unit, NUADU, aboard the TC-2 spacecraft of the Double Star mission. The NPI design is based on a surface reflection technique to measure low energy (~0.3-60 keV) ENAs, while the NUADU instrument is based on a simple design with large geometrical factor and solid state detectors to measure high energy ENAs (~20-300 keV).</p><p>The calibration approach of both NPI sensors were to define the detailed response, including properties such as the angular response function and efficiency of one reference sensor direction then find the relative response of the other sensor directions. Because of the simple geometry of the NUADU instrument, the calibration strategy involved simulations to find the cutoff energy, geometrical factor and angular response. The NUADU sensor head was then calibrated to find the response to particles of different mass and energy. The NPI sensor for the Mars Express mission revealed a so-called priority effect in the sensor that lowers the angular resolution at high detector bias. During the calibration of the Venus Express NPI sensor tests were made which showed that the priority effect is a result of low amplitude (noise) pulses generated in the detector system. The conclusion is that the effect is caused by capacitive couplings between different anode sectors of the sensor. The thresholds on the preamplifiers were set higher on the Venus Express NPI, which removed the priority effect.</p><p>Two of the three ENA experiments, the Double Star NUADU instrument and the Mars Express NPI sensor, have successfully measured ENAs that are briefly described in the thesis. The first ENA measurements at Mars were performed with Mars Express. Initial results from the NPI include measurements of ENAs formed in the Martian magnetosheath and solar wind ENAs penetrating to the nightside of Mars. The first results from NUADU in Earth orbit show the expected ENA emissions from a storm time ring current. Also, together with the HENA instrument on the IMAGE spacecraft, NUADU have produced the first multi-point ENA image of the ring current.</p>