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Stationary magnetospheric convection on November 24, 1981. 1. A case study of “pressure gradient/minimum-B” auroral arc generation (1999)

Galperin, Y. I. ; Bosqued, J. M.

Springer

Annales geophysicae 17 (1999), S. 358-374

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ISSN: 0992-7689

Keywords: Magnetospheric physics (auroral phenomena; magnetospheric configuration and dynamics; plasma sheet).

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract We present two case studies in the night and evening sides of the auroral oval, based on plasma and field measurements made at low altitudes by the AUREOL-3 satellite, during a long period of stationary magnetospheric convection (SMC) on November 24, 1981. The basic feature of both oval crossings was an evident double oval pattern, including (1) a weak arc-type structure at the equatorial edge of the oval/polar edge of the diffuse auroral band, collocated with an upward field-aligned current (FAC) sheet of ≈1.0 μA m−2, (2) an intermediate region of weaker precipitation within the oval, (3) a more intense auroral band at the polar oval boundary, and (4) polar diffuse auroral zone near the polar cap boundary. These measurements are compared with the published magnetospheric data during this SMC period, accumulated by Yahnin et al. and Sergeev et al., including a semi-empirical radial magnetic field profile BZ in the near-Earth neutral sheet, with a minimum at about 10–14 RE. Such a radial BZ profile appears to be very similar to that assumed in the “minimum B/cross-tail line current” model by Galperin et al. (GVZ92) as the “root of the arc”, or the arc generic region. This model considers a FAC generator mechanism by Grad-Vasyliunas-Boström-Tverskoy operating in the region of a narrow magnetic field minimum in the near-Earth neutral sheet, together with the concept of ion non-adiabatic scattering in the “wall region”. The generated upward FAC branch of the double sheet current structure feeds the steady auroral arc/inverted-V at the equatorial border of the oval. When the semi-empirical BZ profile is introduced in the GVZ92 model, a good agreement is found between the modelled current and the measured characteristics of the FACs associated with the equatorial arc. Thus the main predictions of the GVZ92 model concerning the “minimum-B” region are consistent with these data, while some small-scale features are not reproduced. Implications of the GVZ92 model are discussed, particularly concerning the necessary conditions for a substorm onset that were not fulfilled during the SMC period.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s00585-999-0358-0

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2

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Latitudinal distribution of the solar wind properties in the low- and high-pressure regimes: Wind observations (2000)

Lacombe, C. ; Salem, C. ; Mangeney, A. ; [et al.]

Springer

Annales geophysicae 18 (2000), S. 852-865

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ISSN: 0992-7689

Keywords: Interplanetary physics (solar wind plasma)

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract The solar wind properties depend on λ, the heliomagnetic latitude with respect to the heliospheric current sheet (HCS), more than on the heliographic latitude. We analyse the wind properties observed by Wind at 1 AU during about 2.5 solar rotations in 1995, a period close to the last minimum of solar activity. To determine λ, we use a model of the HCS which we fit to the magnetic sector boundary crossings observed by Wind. We find that the solar wind properties mainly depend on the modulus |λ|. But they also depend on a local parameter, the total pressure (magnetic pressure plus electron and proton thermal pressure). Furthermore, whatever the total pressure, we observe that the plasma properties also depend on the time: the latitudinal gradients of the wind speed and of the proton temperature are not the same before and after the closest HCS crossing. This is a consequence of the dynamical stream interactions. In the low pressure wind, at low |λ|, we find a clear maximum of the density, a clear minimum of the wind speed and of the proton temperature, a weak minimum of the average magnetic field strength, a weak maximum of the average thermal pressure, and a weak maximum of the average β factor. This overdense sheet is embedded in a density halo. The latitudinal thickness is about 5° for the overdense sheet, and 20° for the density halo. The HCS is thus wrapped in an overdense sheet surrounded by a halo, even in the non-compressed solar wind. In the high-pressure wind, the plasma properties are less well ordered as functions of the latitude than in the low-pressure wind; the minimum of the average speed is seen before the HCS crossing. The latitudinal thickness of the high-pressure region is about 20°. Our observations are qualitatively consistent with the numerical model of Pizzo for the deformation of the heliospheric current sheet and plasma sheet.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s00585-000-0852-x

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3

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Experimental study of the formation of inverted-V structures and their stratification using AUREOL-3 observations (2000)

Luízar, O. ; Stepanova, M. V. ; Bosqued, J. M. ; [et al.]

Springer

Annales geophysicae 18 (2000), S. 1399-1411

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ISSN: 0992-7689

Keywords: Magnetospheric physics (current systems; energetic particles, precipitating; magnetosphere-ionosphere interactions)

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract Multiple inverted-V structures are commonly observed on the same auroral zone crossing by a lowaltitude orbiting satellite. Such structures appear grouped and apparently result from an ionospheric and/or magnetospheric mechanism of stratification. More than two years of AUREOL-3 satellite observations were analyzed to study their properties and their formation in the framework of the ionosphere-magnetosphere coupling model proposed by Tverskoy. This model predicts some natural periodicity in the electrostatic potential profile (and subsequently in the field-aligned current profiles) that could account for oscillations experimentally observed in the auroral zone, such as successive inverted-Vs. Experimental results obtained during quiet or moderately active periods demonstrate that the number of structures observed within a given event is well described by a ‘scaling’ parameter provided by the hot plasma stratification theory and expressed in terms of the field-aligned current density, the total width of the current band, the plasma sheet ion temperature, and the height-integrated Pedersen conductivity of the ionosphere. The latitudinal width, in the order of 100/200 km at ionospheric altitudes, is relatively independent of the current density, and is determined not only by the existence of a potential difference above the inverted-Vs, but also by basic oscillations of the ionosphere-magnetosphere coupling system predicted by Tverskoy. The large number of cases studied by the AUREOL-3 satellite provides reliable statistical trends which permits the validation of the model and the inference that the multiple structures currently observed can be related directly to oscillations of the magnetospheric potential (or the pressure gradients) on a scale of ∼1000/2000 km in the near-Earth plasma sheet. These oscillations arise in the Tverskoy model and may naturally result when the initial pressure gradients needed to generate a large-scale field-aligned current have a sufficiently wide equatorial scale, of about 1 RE or more.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s00585-000-1399-6

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4

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Stationary magnetospheric convection on November 24, 1981. 2.Small-scale structures in the dayside cusp/cleft (1999)

Galperin, Y. I. ; Bosqued, J. M. ; Kovrazhkin, R. A. ; [et al.]

Springer

Annales geophysicae 17 (1999), S. 375-388

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ISSN: 0992-7689

Keywords: Magnetospheric physics (current systems; magnetopause cusp, and boundary layers; solar wind-magnetosphere interactions)

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract A case study of the dayside cusp/cleft region during an interval of stationary magnetospheric convection (SMC) on November, 24, 1981 is presented, based on detailed measurements made by the AUREOL-3 satellite. Layered small-scale field-aligned current sheets, or loops, superimposed to a narrow V-shaped ion dispersion structure, were observed just equatorward from the region of the “cusp proper”. The equatorward sheet was accompanied by a very intense and short (less than 1 s) ion intensity spike at 100 eV. No major differences were noted of the characteristics of the LLBL, or “boundary cusp”, and plasma mantle precipitation during this SMC period from those typical of the cusp/cleft region for similar IMF conditions. Simultaneous NOAA-6 and NOAA-7 measurements described in Despirak et al. were used to estimate the average extent of the “cusp proper” (defined by dispersed precipitating ions with the energy flux exceeding 10−3 erg cm−2 s−1) during the SMC period, as ≈0.73∼ ILAT width, 2.6–3.4 h in MLT, and thus the recently merged magnetic flux, 0.54–0.70 × 107 Wb. This, together with the average drift velocity across the cusp at the convection throat, ≈0.5 km s−1, allowed to evaluate the cusp merging contribution to the total cross-polar cap potential difference, ≈33.8–43.8 kV. It amounts to a quite significant part of the total cross-polar cap potential difference evaluated from other data. A “shutter” scenario is suggested for the ion beam injection/penetration through the stagnant plasma region in the outer cusp to explain the pulsating nature of the particle injections in the low- and medium-altitude cusp region.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s00585-999-0375-z

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5

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WIND observations of coherent electrostatic waves in the solar wind (1999)

Mangeney, A. ; Salem, C. ; Lacombe, C. ; [et al.]

Springer

Annales geophysicae 17 (1999), S. 307-320

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ISSN: 0992-7689

Keywords: Interplanetary physics (plasma waves and turbulence; solar wind plasma) ; Space plasma physics (electrostatic structures)

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract The time domain sampler (TDS) experiment on WIND measures electric and magnetic wave forms with a sampling rate which reaches 120 000 points per second. We analyse here observations made in the solar wind near the Lagrange point L1. In the range of frequencies above the proton plasma frequency fpi and smaller than or of the order of the electron plasma frequency fpe, TDS observed three kinds of electrostatic (e.s.) waves: coherent wave packets of Langmuir waves with frequencies f ≃ fpe, coherent wave packets with frequencies in the ion acoustic range fpi ≥ f ≥ fpe, and more or less isolated non-sinusoidal spikes lasting less than 1 ms. We confirm that the observed frequency of the low frequency (LF) ion acoustic wave packets is dominated by the Doppler effect: the wavelengths are short, 10 to 50 electron Debye lengths λD. The electric field in the isolated electrostatic structures (IES) and in the LF wave packets is more or less aligned with the solar wind magnetic field. Across the IES, which have a spatial width of the order of ≃25D, there is a small but finite electric potential drop, implying an average electric field generally directed away from the Sun. The IES wave forms, which have not been previously reported in the solar wind, are similar, although with a smaller amplitude, to the weak double layers observed in the auroral regions, and to the electrostatic solitary waves observed in other regions in the magnetosphere. We have also studied the solar wind conditions which favour the occurrence of the three kinds of waves: all these e.s. waves are observed more or less continuously in the whole solar wind (except in the densest regions where a parasite prevents the TDS observations). The type (wave packet or IES) of the observed LF waves is mainly determined by the proton temperature and by the direction of the magnetic field, which themselves depend on the latitude of WIND with respect to the heliospheric current sheet.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s00585-999-0307-y

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6

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A three-dimensional plasma and energetic particle investigation for the wind spacecraft (1995)

Lin, R. P. ; Anderson, K. A. ; Ashford, S. ; [et al.]

Springer

Space science reviews 71 (1995), S. 125-153

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ISSN: 1572-9672

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract This instrument is designed to make measurements of the full three-dimensional distribution of suprathermal electrons and ions from solar wind plasma to low energy cosmic rays, with high sensitivity, wide dynamic range, good energy and angular resolution, and high time resolution. The primary scientific goals are to explore the suprathermal particle population between the solar wind and low energy cosmic rays, to study particle accleration and transport and wave-particle interactions, and to monitor particle input to and output from the Earth's magnetosphere. Three arrays, each consisting of a pair of double-ended semi-conductor telescopes each with two or three closely sandwiched passivated ion implanted silicon detectors, measure electrons and ions above ∼20 keV. One side of each telescope is covered with a thin foil which absorbs ions below 400 keV, while on the other side the incoming 〈400 keV electrons are swept away by a magnet so electrons and ions are cleanly separated. Higher energy electrons (up to ∼1 MeV) and ions (up to 11 MeV) are identified by the two double-ended telescopes which have a third detector. The telescopes provide energy resolution of ΔE/E≈0.3 and angular resolution of 22.5°×36°, and full 4π steradian coverage in one spin (3 s). Top-hat symmetrical spherical section electrostatic analyzers with microchannel plate detectors are used to measure ions and electrons from ∼3 eV to 30 keV. All these analyzers have either 180° or 360° fields of view in a plane, ΔE/E≈0.2, and angular resolution varying from 5.6° (near the ecliptic) to 22.5°. Full 4π steradian coverage can be obtained in one-half or one spin. A large and a small geometric factor analyzer measure ions over the wide flux range from quiet-time suprathermal levels to intense solar wind fluxes. Similarly two analyzers are used to cover the wide range of electron fluxes. Moments of the electron and ion distributions are computed on board. In addition, a Fast Particle Correlator combines electron data from the high sensitivity electron analyzer with plasma wave data from the WAVE experiment (Bougeretet al., in this volume) to study wave-particle interactions on fast time scales. The large geometric factor electron analyzer has electrostatic deflectors to steer the field of view and follow the magnetic field to enhance the correlation measurements.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00751328

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7

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THE CLUSTER ION SPECTROMETRY (CIS) EXPERIMENT (1997)

RÈME, H. ; Bosqued, J. M. ; Sauvaud, J. A. ; [et al.]

Springer

Space science reviews 79 (1997), S. 303-350

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ISSN: 1572-9672

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract The Cluster Ion Spectrometry (CIS) experiment is a comprehensive ionic plasma spectrometry package on-board the four Cluster spacecraft capable of obtaining full three-dimensional ion distributions with good time resolution (one spacecraft spin) with mass per charge composition determination. The requirements to cover the scientific objectives cannot be met with a single instrument. The CIS package therefore consists of two different instruments, a Hot Ion Analyser (HIA) and a time-of-flight ion COmposition and DIstribution Function analyser (CODIF), plus a sophisticated dual-processor-based instrument-control and Data-Processing System (DPS), which permits extensive on-board data-processing. Both analysers use symmetric optics resulting in continuous, uniform, and well-characterised phase space coverage. CODIF measures the distributions of the major ions (H+, He+, He++, and O+) with energies from ~0 to 40 keV/e with medium (22.5°) angular resolution and two different sensitivities. HIA does not offer mass resolution but, also having two different sensitivities, increases the dynamic range, and has an angular resolution capability (5.6° × 5.6°) adequate for ion-beam and solar-wind measurements.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004929816409

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8

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Energetic properties of interplanetary plasma at the earth's orbit following the August 4, 1972 flare (1977)

D'uston, C. ; Bosqued, J. M. ; Cambou, F. ; [et al.]

Springer

Solar physics 51 (1977), S. 217-229

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ISSN: 1573-093X

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract Solar wind and interplanetary magnetic field data were obtained by the PROGNOZ 1 and PROGNOZ 2 satellites during the period following the August 4, 1972 (06∶21 UT) solar flare. A thermalized plasma was recorded one hour after the shock followed two hours later by the plasma ‘piston’ with a bulk velocity higher than 1700 km s-1. The comparison between the PROGNOZ and PIONEER 9 solar wind data shows an attenuation of the plasma properties with the deflection from the flare's meridian.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00240459

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9

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Study of alpha component dynamics in the solar wind using the Prognoz satellite (1977)

Bosqued, J. M. ; D'Uston, C. ; Zertzalov, A. A. ; [et al.]

Springer

Solar physics 51 (1977), S. 231-242

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ISSN: 1573-093X

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract The analysis of solar wind He++ and H+ ion distribution functions, collected over five months by the satellite Prognoz 1, shows that these are in general maxwellian but that often “tails” appear at higher speeds. The existing relation Vα-Tα, the observation of ratios of Tα/Tp ≈ 3.83 and Vα/Vp ≈ 1.035 give evidence of preferential He++ ion heating and acceleration. The criteria for heating by dissipation of hydromagnetic waves proposed by Barnes and Hung (1973) are tested experimentally. Finally, multifluid models are likely to predict certain observations such as dependence of the velocity ratio Vα/Vp on the solar wind flux.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00240460

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