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Dynamics of the bow shock and magnetopause
Jelínek, Karel ; Němeček, Zdeněk (advisor) ; Kudela, Karel (referee) ; Vandas, Marek (referee)
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-...
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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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Role of Magnetosheath Parameters on Magnetopause Processes
Krupařová, Oksana ; Šafránková, Jana (advisor)
The thesis addresses of two regions significant for the solar wind-magnetosphere coupling: the cusp in high geomagnetic latitudes and the low-latitude (LLBL) subsolar magnetopause. A penetration of plasma of a solar origin into the magnetosphere could be realized directly through magnetospheric cusps. The region adjacent to the magnetopause in the cusp vicinity is highly turbulent, occupied by the heated magnetosheath-like plasma with a low drift velocity for which occurrence of vortices is a very common feature. In the first part of the thesis, we present a detailed analysis of a vortex-like structure created by a turbulent plasma flow around the magnetopause indentation above the cusp and using the data from Interball-1 and Magion-4; we find necessary conditions and a possible mechanisms to creation of such structures. The second part concerns the low-latitude boundary layer formation, its spatial structure and temporal changes based on THEMIS multipoint observations. In spite of its crucial role in transfer of mass, momentum, and energy from the solar wind into the magnetosphere, LLBL parameters and their relations to upstream conditions are still under debate. We demonstrate that sudden changes in upstream plasma and magnetic field parameters could lead to reformation of the spatial LLBL profile from...
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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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Role of Magnetosheath Parameters on Magnetopause Processes
Krupařová, Oksana ; Šafránková, Jana (advisor)
The thesis addresses of two regions significant for the solar wind-magnetosphere coupling: the cusp in high geomagnetic latitudes and the low-latitude (LLBL) subsolar magnetopause. A penetration of plasma of a solar origin into the magnetosphere could be realized directly through magnetospheric cusps. The region adjacent to the magnetopause in the cusp vicinity is highly turbulent, occupied by the heated magnetosheath-like plasma with a low drift velocity for which occurrence of vortices is a very common feature. In the first part of the thesis, we present a detailed analysis of a vortex-like structure created by a turbulent plasma flow around the magnetopause indentation above the cusp and using the data from Interball-1 and Magion-4; we find necessary conditions and a possible mechanisms to creation of such structures. The second part concerns the low-latitude boundary layer formation, its spatial structure and temporal changes based on THEMIS multipoint observations. In spite of its crucial role in transfer of mass, momentum, and energy from the solar wind into the magnetosphere, LLBL parameters and their relations to upstream conditions are still under debate. We demonstrate that sudden changes in upstream plasma and magnetic field parameters could lead to reformation of the spatial LLBL profile from...
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Dynamics of the bow shock and magnetopause
Jelínek, Karel ; Němeček, Zdeněk (advisor) ; Kudela, Karel (referee) ; Vandas, Marek (referee)
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-...
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