The Experts below are selected from a list of 1095 Experts worldwide ranked by ideXlab platform
Masayoshi Kojima - One of the best experts on this subject based on the ideXlab platform.
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Structure of Interplanetary Shock Waves from Radio Scintillation Data
Solar Physics, 1997Co-Authors: V. I. Shishov, V. I. Vlasov, Masayoshi KojimaAbstract:The distributions of scintillation index in the interior region of an Interplanetary Shock Wave are obtained by using scintillation observations from Pushchino, Russia. The dependence of scintillation index m on the distance from a Shock front surface Δr is strong and can be represented by a two-component structure of distribution of turbulence level δ Ne)2. The first component occupies a narrow layer with thickness of about 0.02 AU and size of about 0.3 AU, in which the relative enhancement of δNe is about √15. The second component occupies a layer with thickness Δ r=0.1 AU and size of about 0.7 AU, in which the relative enhancement of δ Ne is about √2. The typical distance of the Shock front from the Sun was on the order of 1 AU in the events that we investigated.
V. I. Shishov - One of the best experts on this subject based on the ideXlab platform.
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Structure of Interplanetary Shock Waves from Radio Scintillation Data
Solar Physics, 1997Co-Authors: V. I. Shishov, V. I. Vlasov, Masayoshi KojimaAbstract:The distributions of scintillation index in the interior region of an Interplanetary Shock Wave are obtained by using scintillation observations from Pushchino, Russia. The dependence of scintillation index m on the distance from a Shock front surface Δr is strong and can be represented by a two-component structure of distribution of turbulence level δ Ne)2. The first component occupies a narrow layer with thickness of about 0.02 AU and size of about 0.3 AU, in which the relative enhancement of δNe is about √15. The second component occupies a layer with thickness Δ r=0.1 AU and size of about 0.7 AU, in which the relative enhancement of δ Ne is about √2. The typical distance of the Shock front from the Sun was on the order of 1 AU in the events that we investigated.
Yu. I. Yermolaev - One of the best experts on this subject based on the ideXlab platform.
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Structure of the Front of a Collisionless Oblique Interplanetary Shock Wave from High Time Resolution Measurements of Solar-Wind Plasma Parameters
Geomagnetism and Aeronomy, 2018Co-Authors: V. G. Eselevich, N. L. Borodkova, G. N. Zastenker, O. V. Sapunova, Yu. I. YermolaevAbstract:Data from the Fast Solar Wind Monitor (BMSW) of the science payload onboard the SPEKTR-R satellite and data from instruments on board the WIND spacecraft are used to study statistically the structure of the front of oblique Interplanetary Shock Waves with respect to the θ_Bn angle and the fulfillment of the Rankine–Hugoniot conditions at the fronts of collisionless Shock Waves. The experimental Wavelength of oscillations upstream of the ramp is compared with the estimated theoretical Wavelength to determine that the dispersion of oblique magnetosonic Waves plays the decisive role in the formation of the fronts of quasiperpendicular (45° ≤ θ_Bn < 90°) collisionless Interplanetary Shock Waves with small Mach numbers М _A < 3 and a parameter of β_1 < 1. Comparison of the Rankine–Hugoniot relations M _A(ρ_2/ρ_1), which were measured at the fronts of 47 Interplanetary Shock Waves with β_1 < 5 and Alfven Mach numbers of 1 < М _А < 10 by calculations performed within the ideal magnetic hydrodynamics (MHD), has revealed that the effective adiabatic index γ, which characterizes the processes inside the Shock front, lies mainly within the range from 2 to 5/3.
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catalog of large scale solar wind phenomena during 1976 2000
Cosmic Research, 2009Co-Authors: Yu. I. Yermolaev, N S Nikolaeva, I G Lodkina, Yu M YermolaevAbstract:The main goal of this paper is to compile a catalog of large-scale phenomena in the solar wind over the observation period of 1976-2000 using the measurement data presented in the OMNI database. This work included several stages. At first the original OMNI database was supplemented by certain key parameters of the solar wind that determine the type of the solar wind stream. The following parameters belong to this group: the plasma ratio β , thermal ( NkT ) and kinetic ( mNV 2 ) pressures of the solar wind, the ratio T / T exp of measured and expected temperatures, gradients of the plasma velocity and density, and the magnetic field gradient. The results of visualization of basic plasma parameters that determine the character of the solar wind stream are presented on the website of the Space Research Institute, Moscow. Preliminary identification of basic types of the solar wind stream (FAST and SLOW streams, Heliospheric Current Sheet (HCS), Corotating Interaction Region (CIR), EJECTA (or Interplanetary Coronal Mass Ejections), Magnetic Cloud (MC), SHEATH (compression region before EJECTA/MC), rarified region RARE, and Interplanetary Shock Wave IS) had been made with the help of a preliminary identification program using the preset threshold criteria for plasma and Interplanetary magnetic field parameters. Final identification was done by comparison with the results of visual analysis of the solar wind data. In conclusion, histograms of distributions and statistical characteristics are presented for some parameters of various large-scale types of the solar wind.
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Catalog of large-scale solar wind phenomena during 1976–2000
Cosmic Research, 2009Co-Authors: Yu. I. Yermolaev, N S Nikolaeva, I G Lodkina, M. Yu. YermolaevAbstract:The main goal of this paper is to compile a catalog of large-scale phenomena in the solar wind over the observation period of 1976–2000 using the measurement data presented in the OMNI database. This work included several stages. At first the original OMNI database was supplemented by certain key parameters of the solar wind that determine the type of the solar wind stream. The following parameters belong to this group: the plasma ratio β, thermal ( NkT) and kinetic ( mNV ^2) pressures of the solar wind, the ratio T/T _exp of measured and expected temperatures, gradients of the plasma velocity and density, and the magnetic field gradient. The results of visualization of basic plasma parameters that determine the character of the solar wind stream are presented on the website of the Space Research Institute, Moscow. Preliminary identification of basic types of the solar wind stream (FAST and SLOW streams, Heliospheric Current Sheet (HCS), Corotating Interaction Region (CIR), EJECTA (or Interplanetary Coronal Mass Ejections), Magnetic Cloud (MC), SHEATH (compression region before EJECTA/MC), rarified region RARE, and Interplanetary Shock Wave IS) had been made with the help of a preliminary identification program using the preset threshold criteria for plasma and Interplanetary magnetic field parameters. Final identification was done by comparison with the results of visual analysis of the solar wind data. In conclusion, histograms of distributions and statistical characteristics are presented for some parameters of various large-scale types of the solar wind.
D N Baker - One of the best experts on this subject based on the ideXlab platform.
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Space Weather Effects in the Earth’s Radiation Belts
Space Science Reviews, 2017Co-Authors: D N Baker, A N Jaynes, P. J. Erickson, Joseph F. Fennell, J. C. Foster, P T VerronenAbstract:The first major scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or belts, of very high-energy magnetically trapped charged particles. Early observations of the radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. Recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed many novel properties of the radiation belts, especially for electrons at highly relativistic and ultra-relativistic kinetic energies. In this review we summarize the space weather impacts of the radiation belts. We demonstrate that many remarkable features of energetic particle changes are driven by strong solar and solar wind forcings. Recent comprehensive data show broadly and in many ways how high energy particles are accelerated, transported, and lost in the magnetosphere due to Interplanetary Shock Wave interactions, coronal mass ejection impacts, and high-speed solar wind streams. We also discuss how radiation belt particles are intimately tied to other parts of the geospace system through atmosphere, ionosphere, and plasmasphere coupling. The new data have in many ways rewritten the textbooks about the radiation belts as a key space weather threat to human technological systems.
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a long lived relativistic electron storage ring embedded in earth s outer van allen belt
Science, 2013Co-Authors: D N Baker, S G Kanekal, V C Hoxie, M G Henderson, X Li, Harlan E Spence, S R Elkington, Roland H Friedel, J Goldstein, M K HudsonAbstract:Since their discovery more than 50 years ago, Earth’s Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is composed predominantly of megaelectron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days, depending primarily on external forcing by the solar wind. The spatially separated inner zone is composed of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (>2 MeV) electrons that formed on 2 September 2012 and persisted largely unchanged in the geocentric radial range of 3.0 to ~3.5 Earth radii for more than 4 weeks before being disrupted (and virtually annihilated) by a powerful Interplanetary Shock Wave passage.
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Telescopic and Microscopic views of the magnetosphere: Multispacecraft observations
Space Science Reviews, 2003Co-Authors: D N BakerAbstract:The magnetospheric research community has long sought the capability to view the Sun-Earth system in a global way and to probe concurrently the microphysical details of key physical regions. This objective has now been substantially realized with the combination of the CLUSTER and IMAGE missions. With the additional use of SOHO, ACE, FAST, SAMPEX, POLAR, and geostationary orbit spacecraft, there is a remarkable ability to apply both telescopic and microscopic principles. As an example, a bright active region on the Sun gave rise on 29 March 2001 to a fast halo coronal mass ejection (CME) event observed by SOHO instruments. Subsequently on 31 March, a strong Interplanetary Shock Wave ahead of a magnetic cloud (probably arising from the earlier CME) passed the ACE spacecraft and hit the Earth's magnetosphere. This driver compressed the subsolar magnetopause to ≤4 R_E geocentric distance and initiated a powerful geomagnetic storm (minimum Dst ∼ −360 nT). The CLUSTER set of four spacecraft were located in the midnight sector of the magnetosphere near perigee (r∼4 R_E) at ∼0635 UT and observed a dispersionless injection of energetic (E ≥20 keV) electrons in association with a large magnetospheric substorm expansion phase onset (AE ∼1200 nT). Concurrent to these in situ observations, the IMAGE spacecraft was returning a sequence of global Energetic Neutral Atom (ENA) images from the medium-energy (MENA) and high-energy (HENA) sensor systems. These data showed a very prominent injection of substorm ions in the premidnight (and postdusk) sector of the inner magnetosphere. This event is consistent with a substorm onset that pushed the substorm `injection boundary' far inside of geostationary orbit and far toward the dusk sector. In another event on August 27, 2001, the IMAGE-CLUSTER combination provided evidence that magnetic reconnection began in the mid-tail plasma sheet some 7 min prior to auroral onset and brightening. Alternative interpretations may also be possible even with the multispacecraft data available. Notwithstanding, these data gave an unprecedented view both telescopically and microscopically of a magnetospheric substorm onset and help establish key process timing in the magnetosphere. Such available events reveal the power of multispacecraft observations.
E. A. Pushkar - One of the best experts on this subject based on the ideXlab platform.
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Collision of an Interplanetary Shock Wave with the Earth’s bow Shock. Hydrodynamic parameters and magnetic field
Fluid Dynamics, 2014Co-Authors: A. S. Korolev, E. A. PushkarAbstract:Hydrodynamic parameters and magnetic field generated in each of the Waves in neighborhood of the Earth’s bow Shock when an Interplanetary Shock Wave impinges on it and propagates along its surface are found in the three-dimensional non-plane-polarized formulation within the framework of the ideal magnetohydrodynamic model. The interaction pattern is constructed in the quasi-steady-state formulation as a mosaic of exact solutions, obtained by means of a computer, to the Riemann problem of breakdown of a discontinuity between the states downstream of the impinging Wave and the bow Shock on the traveling line of intersection of their fronts. The calculations are carried out for typical parameters of the quiescent solar wind and the Interplanetary magnetic field in the Earth’s orbit when the plane front of a Shock Wave moves along the Sun-Earth radius with various given velocities. The solutions obtained can be used to interpret measurements carried out by spacecraft in the solar wind and in neighborhood of the Earth’s magnetosphere.
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collision of an Interplanetary Shock Wave with the earth s bow Shock hydrodynamic parameters and magnetic field
Fluid Dynamics, 2014Co-Authors: A. S. Korolev, E. A. PushkarAbstract:Hydrodynamic parameters and magnetic field generated in each of the Waves in neighborhood of the Earth’s bow Shock when an Interplanetary Shock Wave impinges on it and propagates along its surface are found in the three-dimensional non-plane-polarized formulation within the framework of the ideal magnetohydrodynamic model. The interaction pattern is constructed in the quasi-steady-state formulation as a mosaic of exact solutions, obtained by means of a computer, to the Riemann problem of breakdown of a discontinuity between the states downstream of the impinging Wave and the bow Shock on the traveling line of intersection of their fronts. The calculations are carried out for typical parameters of the quiescent solar wind and the Interplanetary magnetic field in the Earth’s orbit when the plane front of a Shock Wave moves along the Sun-Earth radius with various given velocities. The solutions obtained can be used to interpret measurements carried out by spacecraft in the solar wind and in neighborhood of the Earth’s magnetosphere.
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Some features of the Interplanetary Shock Wave interactions connected with the thermal anisotropy and 3D flow past the Earth’s bow Shock
Planetary and Space Science, 2010Co-Authors: S. A. Grib, E. A. PushkarAbstract:Abstract An effect of the pressure anisotropy on the variation in the plasma and magnetic field parameters across the front of a moving fast Shock Wave is examined and the results are compared against experimental data. It is found that the strong magnetic field inside a magnetic cloud with pressure anisotropy affects significantly changes in the plasma parameters across the Shock Wave. The 3D interaction of the plane front of an Interplanetary Shock Wave with the Earth’s bow Shock is considered within the framework of a non-plane-polarized MHD model. The dawn–dusk asymmetry of the interaction due to the influence of the Interplanetary magnetic field and possible abrupt changes in the density and the magnetic field on the dusk flank are described.
