Response of the mid-altitude cusp to rapid rotations of the IMF

Frederic Pitout (1) , P. Escoubet (2) , Y. Bogdanova (3) , E. Georgescu (1) , A. N. Fazakerley (3) , H. Reme (4)

1 MPE - Max-Planck-Institut für Extraterrestrische Physik
2 ESA - Agence Spatiale Européenne = European Space Agency
3 Department of Space and Climate Physics [UCL London]
4 CESR - Centre d'étude spatiale des rayonnements

On 12 August 2003, the four Cluster spacecraft crossed the mid-altitude cusp one after the other a minute or two apart. Shortly after the cusp crossing, two of the Cluster observed three structures poleward of the cusp that appeared and grew in successive satellite passes. In these structures, high fluxes of low-energy magnetosheath-like ions and electrons are observed. The analysis of particle and magnetic field data reveals that it is the cusp region that moved back and forth over the spacecraft. We show that the cusp reacts extremely fast to rotations of the interplanetary magnetic field (IMF) and that each of the three northward turnings of the IMF is accompanied by a poleward displacement of the cusp. The latitudinal component of the cusp velocity at ∼5 Re altitude is estimated to be of the order of 30 km/s.

Keywords: HIGH-ALTITUDE CUSP; INTERPLANETARY MAGNETIC-FIELD; STEADY SOLAR-WIND; CLUSTER OBSERVATIONS; MAGNETOPAUSE

Domains: Sciences of the Universe [physics]

Frederic Pitout, P. Escoubet, Y. Bogdanova, E. Georgescu, A. N. Fazakerley, et al.. Response of the mid-altitude cusp to rapid rotations of the IMF. Geophysical Research Letters, 2006, 33 (11), pp.L11107. ⟨10.1029/2005GL025460⟩. ⟨insu-00357961⟩