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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 36, issue 5 | Copyright
Ann. Geophys., 36, 1319-1333, 2018
https://doi.org/10.5194/angeo-36-1319-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 05 Oct 2018

Regular paper | 05 Oct 2018

Multisatellite observations of the magnetosphere response to changes in the solar wind and interplanetary magnetic field

Galina Korotova1,2, David Sibeck3, Scott Thaller4,9, John Wygant4, Harlan Spence5, Craig Kletzing6, Vassilis Angelopoulos7, and Robert Redmon8 Galina Korotova et al.
  • 1IPST, University of Maryland, College Park, MD, USA
  • 2IZMIRAN, Russian Academy of Sciences, Moscow, Troitsk, Russia
  • 3NASA/GSFC, Code 674, Greenbelt, MD, USA
  • 4College of Science and Engineering, University of Minnesota, Minneapolis, MN, USA
  • 5EOS, University of New Hampshire, Durham, NH, USA
  • 6Department of Physics and Astronomy, Iowa University, Iowa City, IA, USA
  • 7Department of Earth, Planetary and Space sciences, UCLA, Los Angeles, CA, USA
  • 8Solar and Terrestrial Physics division, NGDC/NOAA, Boulder, CO, USA
  • 9LASP, University of Colorado, Boulder, CO, USA

Abstract. We employ multipoint observations of the Van Allen Probes, THEMIS, GOES and Cluster to present case and statistical studies of the electromagnetic field, plasma and particle response to interplanetary (IP) shocks observed by the Wind satellite. On 27 February 2014 the initial encounter of an IP shock with the magnetopause occurred on the postnoon magnetosphere, consistent with the observed alignment of the shock with the spiral IMF. The dayside equatorial magnetosphere exhibited a dusk–dawn oscillatory electrical field with a period of  ∼ 330s and peak-to-peak amplitudes of  ∼ 15mVm−1 for a period of 30min. The intensity of electrons in the energy range from 31.5 to 342KeV responded with periods corresponding to the shock-induced ULF (ultralow frequency) electric field waves. We then perform a statistical study of Ey variations of the electric field and associated plasma drift flow velocities for 60 magnetospheric events during the passage of interplanetary shocks. The Ey perturbations are negative (dusk-to-dawn) in the dayside magnetosphere (followed by positive or oscillatory perturbations) and dominantly positive (dawn-to-dusk direction) in the nightside magnetosphere, particularly near the Sun–Earth line within an L-shell range from 2.5 to 5. The typical observed amplitudes range from 0.2 to 6mVm−1 but can reach 12mV during strong magnetic storms. We show that electric field perturbations increase with solar wind pressure, and the changes are especially marked in the dayside magnetosphere. The direction of the Vx component of plasma flow is in agreement with the direction of the Ey component and is antisunward at all local times except the nightside magnetosphere, where it is sunward near the Sun–Earth line. The flow velocities Vx range from 0. 2 to 40kms−1 and are a factor of 5 to 10 times stronger near noon as they correspond to greater variations of the electric field in this region. We demonstrate that the shock-induced electric field signatures can be classified into four different groups according to the initial Ey electric field response and these signatures are dependent on local time. Negative and bipolar pulses predominate on the dayside while positive pulses occur on the nightside. The ULF electric field pulsations of Pc and Pi types produced by IP shocks are observed at all local times and in the range of periods from several tens of seconds to several minutes. We believe that most electric field pulsations of the Pc5 type in the dayside magnetosphere at L<6 are produced by field line resonances. We show that the direction of the shock normal determines the direction of the propagation of the shock-induced magnetic and plasma disturbances. The observed directions of velocity Vy predominately agree with those expected for the given spiral or orthospiral shock normal orientation.

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We employ multipoint observations of the Van Allen Probes, THEMIS, GOES and Cluster to present case and statistical studies of the electromagnetic field, plasma and particle response to interplanetary (IP) shocks observed by Wind. We perform a statistical study of Ey variations of the electric field and associated plasma drift flow velocities for 60 magnetospheric events during the passage of interplanetary shocks.
We employ multipoint observations of the Van Allen Probes, THEMIS, GOES and Cluster to present...
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