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Effect of a northward turning of the interplanetary magnetic field on cusp precipitation as observed by Cluster.
J GEOPHYS RES-SPACE
, Article A07S13. 10.1029/2007JA012771.
The immediate effect of the rotation of the interplanetary magnetic field (IMF) from southward to northward on cusp precipitation has been rarely observed by a polar orbiting satellite in the past. The four Cluster spacecraft observed such an event on 23 September 2004 as they were crossing the polar cusp within 2-16 min from each other. Between the first three and the last spacecraft crossing the cusp, the IMF rotated from southward to northward with a dominant By (GSM) component. For the first time we can examine the changes in the particle precipitation immediately after such IMF change. The first two spacecraft observed typical IMF-southward ion dispersion, while the last one observed both an IMF-southward-like dispersion in the boundary layer and an IMF-northward dispersion in the cusp. After the IMF turning, the cusp is shown to have grown in size in both the poleward and equatorward directions. A three-dimensional magnetohydrodynamic simulation is used to determine the locations of the sources of the ions and the topology of the magnetic field during the event.
|Title:||Effect of a northward turning of the interplanetary magnetic field on cusp precipitation as observed by Cluster|
|Keywords:||GROUND-BASED OBSERVATIONS, LOW-ALTITUDE OBSERVATIONS, POLAR CUSP, MAGNETOSHEATH PLASMA, LATITUDE, IMF, MAGNETOSPHERE, RECONNECTION, CONVECTION, MAGNETOPAUSE|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
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