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 ∼330 s and
peak-to-peak amplitudes of ∼15 mV m−1 for a period of 30 min.
The intensity of electrons in the energy range from 31.5 to 342 KeV
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 6 mV m−1 but can
reach 12 mV 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 40 km s−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.
