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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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Correlation properties of magnetosheath fluctuations
Gutynska, Olga ; Šafránková, Jana (advisor) ; Vandas, Marek (referee) ; Souček, Jan (referee)
Title: Correlation properties of magnetosheath fluctuations Author: Olga Gutynska Department: Department of Surface and Plasma Science Supervisor: Prof. RNDr. Jana Šafránková, DrSc. e-mail address: Jana.Safrankova@mff.cuni.cz Abstract: This thesis deals with fluctuations of the magnetic field (MF) and plasma density in different magnetosheath locations. The statistical study of the correlation length of these quantities has shown that these lengths are surprisingly low for both the ion flux and MF (approx. 1 RE). However, the correlation length increases with an increasing correlation between the magnetosheath and interplanetary magnetic fields (IMF). Further, we have found that the correlation length of MF fluctuations depends on the solar wind speed, on a correlation between IMF and magnetosheath MF fluctua- tions, and on the amplitude of fluctuations. The statistical study of radial profiles of cross-correlations between MF and plasma density at the subsolar and flank regions based on Cluster and THEMIS magnetosheath observa- tions revealed better correlations toward the magnetopause. A study of the modification of the IMF direction in the magnetosheath has shown that a reliable prediction of the magnetosheath BZ sign requires |IMF BZ| > 2 nT and that this prediction is more precise during solar minimum....
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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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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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Correlation properties of magnetosheath fluctuations
Gutynska, Olga ; Šafránková, Jana (advisor) ; Vandas, Marek (referee) ; Souček, Jan (referee)
Title: Correlation properties of magnetosheath fluctuations Author: Olga Gutynska Department: Department of Surface and Plasma Science Supervisor: Prof. RNDr. Jana Šafránková, DrSc. e-mail address: Jana.Safrankova@mff.cuni.cz Abstract: This thesis deals with fluctuations of the magnetic field (MF) and plasma density in different magnetosheath locations. The statistical study of the correlation length of these quantities has shown that these lengths are surprisingly low for both the ion flux and MF (approx. 1 RE). However, the correlation length increases with an increasing correlation between the magnetosheath and interplanetary magnetic fields (IMF). Further, we have found that the correlation length of MF fluctuations depends on the solar wind speed, on a correlation between IMF and magnetosheath MF fluctua- tions, and on the amplitude of fluctuations. The statistical study of radial profiles of cross-correlations between MF and plasma density at the subsolar and flank regions based on Cluster and THEMIS magnetosheath observa- tions revealed better correlations toward the magnetopause. A study of the modification of the IMF direction in the magnetosheath has shown that a reliable prediction of the magnetosheath BZ sign requires |IMF BZ| > 2 nT and that this prediction is more precise during solar minimum....
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Evolution of interplanetary coronal mass ejections
Lynnyk, Andrii ; Vandas, Marek (advisor) ; Přech, Lubomír (referee) ; Rušín, Vojtěch (referee)
Title: Evolution of Interplanetary Coronal Mass Ejections Author: Andrii Lynnyk Department: Department of Surface and Plasma Science Supervisor: RNDr. Marek Vandas, DrSc. e-mail address: vandas@ig.cas.cz Abstract: This thesis deals with deformation of the Interplanetary Coronal Mass Ejections (ICMEs) and their sub-class Magnetic Clouds (MCs) during their propagation in the Solar Wind (SW). The statistical study of the expanded MCs has shown that expansion greatly affects the MC internal magnetic field. We had shown that this influence is more clear for the MCs observed close to their axes. The study of the stand-off shock distance in front of the supersonic ICME confirms a smooth deformation of the ICMEs along their path from the Sun into interplanetary space. We observed that this deformation is increasing with the velocity of the ICME. This study also confirmed the difference in sheaths that are created in front of expanding and non-expanding ICMEs. We found that velocity distribution inside the MC is not uniform and it has large fluctuations. We found that the MC cross-section is usually strongly deformed. Keywords: interplanetary coronal mass ejection, magnetic cloud, magnetosheath, flux rope, magnetic field, shock, fitting
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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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Vývoj meziplanetární rázové vlny v přechodové oblasti
Koval, A. ; Šafránková, J. ; Němeček, Z. ; Přech, L. ; Hayosh, Mykhaylo
Propagation of an interplanetary shock through the solar wind and magnetosheath is studied. The data from spacecraft allows determining both local and global shock planes and shock propagation speeds in the solar wind as well as local shock parameters in the magnetosheath. A mutual comparison of these parameters indicates that the shock front decelerates and curves in the magnetosheats. Magnetic field and plasma parameters are well reproduced by 3D MHD BARTS-R-US model.
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