WINDMI is a low dimensional plasma physics-based model of the coupled magnetosphere-ionosphere system. The nonlinear system of ordinary differential equations describes the energy balance between the basic nightside components of the system using the solar wind driving voltage as input. Of the eight dynamical variables determined by the model, the region 1 field aligned current and ring current energy is compared to the westward auroral electrojet AL index and equatorial geomagnetic disturbance storm time Dst index. The WINDMI model is used to analyze the magnetosphere-ionosphere system during major geomagnetic storms and substorms which are community campaign events. Numerical experiments using the WINDMI model are also used to assess the question of how much interplanetary shock events contribute to the geoeffectiveness of solar wind drivers. For two major geomagnetic storm intervals, it is found that the magnetic field compressional jump is important to producing the changes in the AL index. Further, the WINDMI model is implemented to compute model AL and Dst predictions every ten minutes using real-time solar wind data from the ACE satellite as input. Real-Time WINDMI has been capturing substorm and storm activity, as characterized by the AL and Dst indices, reliably since February 2006 and is validated by comparison with ground-based measurements of the indices. Model results are compared for three different candidate input solar wind driving voltage formulas. Modeling of the Dst index is further developed to include the additional physical processes of tail current increases and sudden commencement. A new model, based on WINDMI, is developed using the dayside magnetopause and magnetosphere current systems to model the magnetopause boundary motion and the dayside region 1 field aligned current which is comparable to the auroral upper AU index. / text

<p>This thesis treats interaction between electromagnetic waves and localized plasma oscillations. Two specific physical systems are considered, namely artificially excited magnetic field-aligned irregularities (striations) and naturally excited lower hybrid solitary structures (LHSS). Striations are mainly density depletions of a few percent that are observed when a powerful electromagnetic wave, a pump wave, is launched into the ionosphere. The striations are formed by upper hybrid (UH) oscillations that are localized in the depletion where they are generated by the linear conversion of the pump field on the density gradients. However, the localization is not complete as the UH oscillation can convert to a propagating electromagnetic Z mode wave. This process, termed Z mode leakage, causes damping of the localized UH oscillation. The Z mode leakage is investigated and the theory predicts non-Lorentzian skewed shapes of the resonances for the emitted Z mode radiation. Further, the interaction between individual striations facilitated by the Z mode leakage is investigated. The LHSS are observed by spacecraft in the ionosphere and magnetosphere as localized waves in the lower hybrid (LH) frequency range that coincides with density cavities. The localized waves are immersed in non-localized wave activity. The excitation of localized waves with frequencies below LH frequency is modelled by scattering of electromagnetic magnetosonic (MS) waves off a preexisting density cavity. It is shown analytically that an incident MS wave with frequency less than the minimum LH frequency inside the cavity is focused to localized waves with left-handed rotating wave front. In addition, the theory is shown to be consistent with observations by the Freja satellite. For frequencies between the minimum LH frequency inside the cavity and the ambient LH frequency, the MS wave is instead mode converted and excites pressure driven LH oscillations. This process is studied in a simplified geometry.</p>

This thesis treats interaction between electromagnetic waves and localized plasma oscillations. Two specific physical systems are considered, namely artificially excited magnetic field-aligned irregularities (striations) and naturally excited lower hybrid solitary structures (LHSS). Striations are mainly density depletions of a few percent that are observed when a powerful electromagnetic wave, a pump wave, is launched into the ionosphere. The striations are formed by upper hybrid (UH) oscillations that are localized in the depletion where they are generated by the linear conversion of the pump field on the density gradients. However, the localization is not complete as the UH oscillation can convert to a propagating electromagnetic Z mode wave. This process, termed Z mode leakage, causes damping of the localized UH oscillation. The Z mode leakage is investigated and the theory predicts non-Lorentzian skewed shapes of the resonances for the emitted Z mode radiation. Further, the interaction between individual striations facilitated by the Z mode leakage is investigated. The LHSS are observed by spacecraft in the ionosphere and magnetosphere as localized waves in the lower hybrid (LH) frequency range that coincides with density cavities. The localized waves are immersed in non-localized wave activity. The excitation of localized waves with frequencies below LH frequency is modelled by scattering of electromagnetic magnetosonic (MS) waves off a preexisting density cavity. It is shown analytically that an incident MS wave with frequency less than the minimum LH frequency inside the cavity is focused to localized waves with left-handed rotating wave front. In addition, the theory is shown to be consistent with observations by the Freja satellite. For frequencies between the minimum LH frequency inside the cavity and the ambient LH frequency, the MS wave is instead mode converted and excites pressure driven LH oscillations. This process is studied in a simplified geometry.

Idag finns det omkring 5 000 operativa satelliter i omloppsbana runt jorden. Bland dessa finns MATS, DMSP-17/18 och Swarm-A/B/C. De tre satellitprogrammen ger olika data från jordens övre atmosfär där MATS bland annat observerar infraröd emission, DMSP mäter elektron- och jonnedfall från rymden och Swarm bland annat mäter variationer i jordens geomagnetiska fält. Dessa data ger möjlighet att analysera aurora. Aurora, även känt som polarsken, är ett fantastiskt ljusfenomen som kan urskiljas i olika färger och som har forskats på under flera decennier. Till följd av detta finns även möjligheten att göra gymnasieelever mer intresserade av rymden. När elever deltar i autentiskt lärande kan det bidra till ökat intresse inom naturvetenskap. Studien syftar till att undersöka auroraregionerna och jämföra data mellan MATS, DMSP och Swarm för att skapa en helhetsbild av fenomenet. Dessutom utvecklas ett lektionsmaterial som syftar till att öka intresset för rymden och fysik i allmänhet bland gymnasieelever. Metoden för den tekniska delen innefattade att finna konjunktioner mellan MATS och en annan satellit eftersom satelliterna ska ge data för samma fenomen. Under en konjunktion behövde banorna stämma överens samtidigt som satelliterna skulle ha tillgänglig data vid tidpunkten. För den pedagogiska delen har en enkätstudie använts för att samla in lärares åsikter om utveckling och utvärdering av lektionsmaterialet. Fem konjunktioner undersöktes och resultaten visade på en ökning av elektron och jonenergi samt flöde i auroraregioner. Ett fall visade en svag uppåtriktad ström som en potentiell förklaring till den ökade energin, vilket möjligtvis tillåter elektronerna att accelerera mot jorden och därav ökar flödet. Enkätstudien visade att det fanns ett intresse för ett lektionsmaterial. Fokus skulle ligga på att skapa ett autentiskt material där eleverna fick en genomgång om hur polarsken uppstår och därefter diskutera frågor kopplade till materialet. Utvärderingen visade att syftet och lärandemålen för lektionen hade uppfyllts. Eleverna deltog aktivt i diskussioner, ställde följdfrågor och ansågs vara intresserade av materialet. / Today there are around 5 000 operative satellites currently in orbit. MATS,DMSP-17/18 and Swarm-A/B/C are just a few among them. These three satellite programs produce different data from Earth’s upper atmosphere. MATS observe infrared emission, DMSP measure electron- and ion precipitation and Swarm measure variations in Earth’s geomagnetic field. This data provides the opportunity to analyze aurora. Aurora, also known as polar lights, is a fantasticlight phenomenon that can be observed in different colors and has been researched for decades. As a result, there is also a possibility to increase the interest among high school students to learn about space. A contribution to their interest can be seen when the students are allowed to participate in authentic learning.The study aimed to investigate aurora regions and compare data between MATS, DMSP and Swarm in order to create a comprehensive picture of the phenomenon. Additionally, an educational material was developed with the aim of increasing interest in space and physics in general among high school students. The methodology for the technical part consisted of finding conjunctions between MATS and one other satellite. This was because of the fact that the satellites were required to give data from the same phenomenon. During a conjunction the orbits of the satellites had to correspond and the satellites also needed to have available data from the time period. A survey study was conducted for the pedagogical part in order to collect opinions from teachers about the development and evaluation of the educational material. Five conjunctions were examined, and the results indicated an increase in electron and ion energy as well as flux in auroral regions. One case showed a weak upward current as a potential explanation for the increase in energy, possibly allowing electrons to accelerate towards the Earth and thus increasing the flux. The survey study showed that there was an interest in the educational material. The focus would be to create an authentic material where students were given an overview of how aurora occur followed by questions to discuss related to the material. The evaluation showed that the purpose and learning objectives of the lesson had been fulfilled. Students actively participated in discussions, asked follow-up questions and were considered to be interested in the material.