Interplanetary magnetic field rotations followed from L1 to the ground: the response of the Earth's magnetosphere as seen by multi-spacecraft and ground-based observations

Abstract

Abstract.A study of the interaction of solar wind magnetic field rotations with the Earth's magnetosphere is performed. For this event there is, for the first time, a full coverage over the dayside magnetosphere with multiple (multi)spacecraft missions from dawn to dusk, combined with ground magnetometers, radar and an auroral camera, this gives a unique coverage of the response of the Earth's magnetosphere. After a long period of southward IMF B z and high dynamic pressure of the solar wind, the Earth's magnetosphere is eroded and compressed and reacts quickly to the turning of the magnetic field. We use data from the solar wind monitors ACE and Wind and from magnetospheric missions Cluster, THEMIS, DoubleStar and Geotail to investigate the behaviour of the magnetic rotations as they move through the bow shock and magnetosheath. The response of the magneCorrespondence to: M. Volwerk (martin.volwerk@oeaw.ac.at) tosphere is investigated through ground magnetometers and auroral keograms. It is found that the solar wind magnetic field drapes over the magnetopause, while still co-moving with the plasma flow at the flanks. The magnetopause reacts quickly to IMF B z changes, setting up field aligned currents, poleward moving aurorae and strong ionospheric convection. Timing of the structures between the solar wind, magnetosheath and the ground shows that the advection time of the structures, using the solar wind velocity, correlates well with the timing differences between the spacecraft. The reaction time of the magnetopause and the ionospheric current systems to changes in the magnetosheath B z seem to be almost immediate, allowing for the advection of the structure measured by the spacecraft closest to the magnetopause.

Increases in plasma sheet temperature with solar wind driving during substorm growth phases

“…As magnetopause reconnection occurs, the dayside magnetosphere is eroded, moving inward by 10-20% [Aubry, 1970;Holzer and Slavin, 1978;Sibeck et al, 1991;Shue et al, 1997;Volwerk et al, 2011], the cusps move equatorward and the magnetotail expands to accommodate the increasing open magnetic flux created by the reconnection. The increase in flaring of the near-Earth magnetotail increases the solar wind ram pressure transmitted through the magnetopause, which is balanced by an increase in the total pressure exerted from within by the increased magnetic flux in the lobes [Coroniti and Kennel, 1972;Shue et al, 1997].…”

Multipoint observation of the response of the magnetosphere and ionosphere related to the sudden impulse event on 19 November 2007

“…Recently, other studies, as those of Samsonov et al (2011) or Volwerk et al (2011, dealt with the wave propagation through the magnetosphere. They focused their attention on other topics as pulsation propagation or the response of the magnetosphere to B z changes.…”

Joint Cluster/Ground‐Based Studies in the First 20 Years of the Cluster Mission

“…Magnetospheric dynamics are highly dependent upon IMF orientation, in particular the north-south (B Z ) component. Volwerk et al (2011) used an excellent conjunction of spacecraft (including both the Cluster and THEMIS multi-spacecraft constellations) and ground-based instrumentation to study a series of rotations in the IMF B Z component, and their interaction with the Earth's magnetosphere, from the L1 Lagrangian point to the ground. These rotations were observed in the solar wind by ACE and Wind (separated by 70 R E in the Y GSE direction); comparing the normals of the rotation fronts and the time delays between observations of the fronts at these two spacecraft, the authors found a mixture of planar, concave and convex fronts.…”