At the end of August 2007, Venus, Earth and Ulysses were aligned within a few degrees. This unusu... more At the end of August 2007, Venus, Earth and Ulysses were aligned within a few degrees. This unusual event gives the opportunity to attempt a coordinated study on the radial evolution of solar wind turbulence and coronal transients like CMEs between 0.7 and 1.4 AU. Interplanetary magnetic field data and moments of proton velocity distribution function such as density, speed and
Magnetic turbulence is found in most space plasmas, including the Earth’s magnetosphere, and the ... more Magnetic turbulence is found in most space plasmas, including the Earth’s magnetosphere, and the interaction region between the magnetosphere and the solar wind. Recent spacecraft observations of magnetic turbulence in the ion foreshock, in the magnetosheath, in the polar cusp regions, in the magnetotail, and in the high latitude ionosphere are reviewed. It is found that: 1. A large share of magnetic turbulence in the geospace environment is generated locally, as due for instance to the reflected ion beams in the ion foreshock, to temperature anisotropy in the magnetosheath and the polar cusp regions, to velocity shear in the magnetosheath and magnetotail, and to magnetic reconnection at the magnetopause and in the magnetotail. 2. Spectral indices close to the Kolmogorov value can be recovered for low frequency turbulence when long enough intervals at relatively constant flow speed are analyzed in the magnetotail, or when fluctuations in the magnetosheath are considered far downstre...
ABSTRACT The interplanetary magnetic field and related parameters are known to vary with solar cy... more ABSTRACT The interplanetary magnetic field and related parameters are known to vary with solar cycle In this study the distributions of the magnetic field components and related parameters such as the winding angle of the field and the solar wind velocity are considered using ACE measurements for the solar cycle 23 variations at 1 0 AU The field behaviour is believed to be a weakly stationary random function which ensures the stationarity of the average and correlation functions We investigate the time variation of magnetic field component distributions and its implication to the variation in the solar source surface field
Recent satellite observations have shown some new characteristics of the cross-tail current and f... more Recent satellite observations have shown some new characteristics of the cross-tail current and field-aligned current different from the conventional picture. The cross-tail current sheet sometimes becomes different from the normal Harris-type current sheet. Namely, it becomes bifurcated or displaced from the center of the neutral sheet. Field-aligned currents near the plasma sheet-lobe boundary show also different structure from the region
Recent studies provide evidence for the multi-scale nature of magnetic turbulence in the plasma s... more Recent studies provide evidence for the multi-scale nature of magnetic turbulence in the plasma sheet. The anisotropy characteristics of the magnetic fluctuations are also scale dependent and show a changing spatial pattern depending on the occurrence of rapid bursty flows inside the plasma sheet. In order to explain the observed anisotropy patterns, we consider several complementary mechanisms, which include highly
Cosmic Rays in Interplanetary Magnetic Fields is an excellent monograph in the 'Geophysics an... more Cosmic Rays in Interplanetary Magnetic Fields is an excellent monograph in the 'Geophysics and Astrophysics Monographs' series. One finds a thorough account of theoretical and experimental aspects of energetic solar particles propagation in the interplanetary space prefaced by short consideration of the physical properties of the heliomagnetosphere. The approach is quantitative reflecting the strong physical background of such processes as acceleration and transport of energetic particles due to various mechanisms, formation of accelerated particles spectra, modulation of galactic CR, short-term variations of the CR intensity. Particularly interesting is a unified theoretical approach based on consideration of CR as a highly energetic component of the cosmic plasma which allows to describe this component by means of plasma physics methods. The monograph is well suited for an understanding of advanced knowledge in the field including the results reported at the XVIII Internat...
ABSTRACT Experimental studies of multi-scale energy transfer associated with small-scale intermit... more ABSTRACT Experimental studies of multi-scale energy transfer associated with small-scale intermittence in turbulent plasma sheet are essential for understanding various physical processes, e.g. Reynolds number dependent dissipation mechanisms, turbulent mixing or magnetic reconnection. The transitory properties of fluctuations, finite size and boundary effects, however, make the statistical results on intermittent turbulence often ambiguous. We concentrate on intrinsic features of plasma sheet intermittence investigating their origin and dynamical nature. In particular, we investigate the scale-dependent diversity of fluctuations and provide evidence for at least three different sources to explain the events with increased intermittence level: small-scale turbulence, boundary-layer turbulence and multiple bursty bulk flows.
At the end of August 2007, Venus, Earth and Ulysses were aligned within a few degrees. This unusu... more At the end of August 2007, Venus, Earth and Ulysses were aligned within a few degrees. This unusual event gives the opportunity to attempt a coordinated study on the radial evolution of solar wind turbulence and coronal transients like CMEs between 0.7 and 1.4 AU. Interplanetary magnetic field data and moments of proton velocity distribution function such as density, speed and
Magnetic turbulence is found in most space plasmas, including the Earth’s magnetosphere, and the ... more Magnetic turbulence is found in most space plasmas, including the Earth’s magnetosphere, and the interaction region between the magnetosphere and the solar wind. Recent spacecraft observations of magnetic turbulence in the ion foreshock, in the magnetosheath, in the polar cusp regions, in the magnetotail, and in the high latitude ionosphere are reviewed. It is found that: 1. A large share of magnetic turbulence in the geospace environment is generated locally, as due for instance to the reflected ion beams in the ion foreshock, to temperature anisotropy in the magnetosheath and the polar cusp regions, to velocity shear in the magnetosheath and magnetotail, and to magnetic reconnection at the magnetopause and in the magnetotail. 2. Spectral indices close to the Kolmogorov value can be recovered for low frequency turbulence when long enough intervals at relatively constant flow speed are analyzed in the magnetotail, or when fluctuations in the magnetosheath are considered far downstre...
ABSTRACT The interplanetary magnetic field and related parameters are known to vary with solar cy... more ABSTRACT The interplanetary magnetic field and related parameters are known to vary with solar cycle In this study the distributions of the magnetic field components and related parameters such as the winding angle of the field and the solar wind velocity are considered using ACE measurements for the solar cycle 23 variations at 1 0 AU The field behaviour is believed to be a weakly stationary random function which ensures the stationarity of the average and correlation functions We investigate the time variation of magnetic field component distributions and its implication to the variation in the solar source surface field
Recent satellite observations have shown some new characteristics of the cross-tail current and f... more Recent satellite observations have shown some new characteristics of the cross-tail current and field-aligned current different from the conventional picture. The cross-tail current sheet sometimes becomes different from the normal Harris-type current sheet. Namely, it becomes bifurcated or displaced from the center of the neutral sheet. Field-aligned currents near the plasma sheet-lobe boundary show also different structure from the region
Recent studies provide evidence for the multi-scale nature of magnetic turbulence in the plasma s... more Recent studies provide evidence for the multi-scale nature of magnetic turbulence in the plasma sheet. The anisotropy characteristics of the magnetic fluctuations are also scale dependent and show a changing spatial pattern depending on the occurrence of rapid bursty flows inside the plasma sheet. In order to explain the observed anisotropy patterns, we consider several complementary mechanisms, which include highly
Cosmic Rays in Interplanetary Magnetic Fields is an excellent monograph in the 'Geophysics an... more Cosmic Rays in Interplanetary Magnetic Fields is an excellent monograph in the 'Geophysics and Astrophysics Monographs' series. One finds a thorough account of theoretical and experimental aspects of energetic solar particles propagation in the interplanetary space prefaced by short consideration of the physical properties of the heliomagnetosphere. The approach is quantitative reflecting the strong physical background of such processes as acceleration and transport of energetic particles due to various mechanisms, formation of accelerated particles spectra, modulation of galactic CR, short-term variations of the CR intensity. Particularly interesting is a unified theoretical approach based on consideration of CR as a highly energetic component of the cosmic plasma which allows to describe this component by means of plasma physics methods. The monograph is well suited for an understanding of advanced knowledge in the field including the results reported at the XVIII Internat...
ABSTRACT Experimental studies of multi-scale energy transfer associated with small-scale intermit... more ABSTRACT Experimental studies of multi-scale energy transfer associated with small-scale intermittence in turbulent plasma sheet are essential for understanding various physical processes, e.g. Reynolds number dependent dissipation mechanisms, turbulent mixing or magnetic reconnection. The transitory properties of fluctuations, finite size and boundary effects, however, make the statistical results on intermittent turbulence often ambiguous. We concentrate on intrinsic features of plasma sheet intermittence investigating their origin and dynamical nature. In particular, we investigate the scale-dependent diversity of fluctuations and provide evidence for at least three different sources to explain the events with increased intermittence level: small-scale turbulence, boundary-layer turbulence and multiple bursty bulk flows.
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Papers by Z. Voeroes