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Relations between geomagnetic activity and magnetopause locations
Mokrý, Adrián ; Němeček, Zdeněk (advisor) ; Grygorov, Kostiantyn (referee)
The magnetopause separates the area in which all phenomena are influenced by the Earth's magnetic field from the interplanetary space filled with the solar wind. Our ability to predict its location is a measure of our understanding of the processes that take place in this space. The present thesis is focused on the analysis of a database of roughly 30,000 magnetopause passes observed from the subsolar region to the tail of the magnetosphere with the aim of clarifying/verifying the influence of magnetospheric electric currents represented by geomagnetic indices. A linearly decreasing dependence of the magnetopause position on the AE index was found from the subsolar point down the tail. Furthermore, a correlation analysis of the influence of the Dst index was performed and we have found the delay of about 5 hours between the Dst peak and magnetopause displacement in the subsolar region, while the results are contradictory on the night side and more observations would be collected to clarify them.
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Empirical modeling of the location of the Earth's magnetopause
Machková, Anna ; Němec, František (advisor) ; Grygorov, Kostiantyn (referee)
This bachelor thesis focuses on suggesting possible improvements of the existing models of the magnetopause stand-off distance, i.e., on identification of the parameters which are not properly (or not at all) included. Magnetopause is a border between the terrestrial and interplanetary magnetic fields, where the pressure of the Earth's magnetic field balances the solar wind dynamic pressure. In order to analyze the parameters, which have an influence on the magnetopause radial distance, we perform a systematic study of an existing database of 16800 magnetopause crossings registered by 8 different satellites. We focus on the effect of the topology of the terrestrial magnetic field, which is not perfectly dipolar, and whose values close to the subsolar point exhibit significant diurnal and annual variations. Another analyzed phenomenon is the magnetospheric ring current and its influence on the magnetic field strength near the magnetopause. Possible changes of this magnetic field have a direct influence on the magnetopause distance from the Earth. Attention is also devoted to the potentially different positions of the magnetopause at the times of fast and slow solar wind. Finally, we discuss complications related to the satellite orbits and the resulting uneven spatial distribution of the used data set.
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Empirical modeling of the location of the Earth's magnetopause
Machková, Anna ; Němec, František (advisor) ; Grygorov, Kostiantyn (referee)
This bachelor thesis focuses on suggesting possible improvements of the existing models of the magnetopause stand-off distance, i.e., on identification of the parameters which are not properly (or not at all) included. Magnetopause is a border between the terrestrial and interplanetary magnetic fields, where the pressure of the Earth's magnetic field balances the solar wind dynamic pressure. In order to analyze the parameters, which have an influence on the magnetopause radial distance, we perform a systematic study of an existing database of 16800 magnetopause crossings registered by 8 different satellites. We focus on the effect of the topology of the terrestrial magnetic field, which is not perfectly dipolar, and whose values close to the subsolar point exhibit significant diurnal and annual variations. Another analyzed phenomenon is the magnetospheric ring current and its influence on the magnetic field strength near the magnetopause. Possible changes of this magnetic field have a direct influence on the magnetopause distance from the Earth. Attention is also devoted to the potentially different positions of the magnetopause at the times of fast and slow solar wind. Finally, we discuss complications related to the satellite orbits and the resulting uneven spatial distribution of the used data set.
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Structure, Location, and Dynamics of the Magnetopause
Grygorov, Kostiantyn ; Přech, Lubomír (advisor) ; Bárta, Miroslav (referee) ; Hayosh, Mykhaylo (referee)
Title: Structure, Location, and Dynamics of the Magnetopause Author: Kostiantyn Grygorov Department: Department of Surface and Plasma Science Supervisor: Doc. RNDr. Lubomír Přech, Dr., Department of Surface and Plasma Science e-mail address: Prech@mbox.troja.mff.cuni.cz Abstract: The magnetopause is the key region where the collisionless plasma from the Sun penetrates into the Earth's magnetosphere. A transfer of the plasma, momentum, and energy across the magnetopause is highly variable and depends on solar wind conditions, similarly as the magnetopause location. This thesis addresses the solar wind-magnetosphere interaction in two different regions: the dayside equatorial magnetopause and the far magnetotail. In the first part of the thesis, we present a detailed analysis of the interplanetary (IP) shock propa- gation through the solar wind, its impact on the substorm development and its influence on the far magnetotail. We demonstrate that the change of the solar wind VZ component across the shock creates a huge kink that propagates along the tail. The second part of the thesis is devoted to the influence of prolonged intervals of a radial interplanetary magnetic field (IMF) on the dayside magnetopause. The statistical analysis of the equatorial magnetopause shape and location based on THEMIS observations...
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