Escoubet, CP;
Bosqued, JM;
Berchem, J;
Trattner, KJ;
Taylor, MGGT;
Pitout, F;
Laakso, H;
... Fazakerley, A; + view all
(2006)
Temporal evolution of a staircase ion signature observed by Cluster in the mid-altitude polar cusp.
Geophysical Research Letters
, 33
(7)
, Article L07108. 10.1029/2005GL025598.
![[thumbnail of 2005GL025598.pdf]](https://discovery.ucl.ac.uk/style/images/fileicons/application_pdf.png) Preview |
PDF
2005GL025598.pdf Available under License : See the attached licence file. Download (2MB) |
Abstract
We use the Cluster string of pearls configuration to investigate temporal variations of ion precipitation in the mid-altitude polar cusp. On 7 Aug. 2004, Cluster 4 was moving poleward through the Northern cusp, followed by Cluster 1, Cluster 2, and finally Cluster 3. The Wind spacecraft detected a Southward turning of the Interplanetary Magnetic Field ( IMF) at the beginning of the cusp crossings and IMF-Bz stayed negative throughout. Cluster 4 observed a high energy step in the ion dispersion around 1 keV on the equatorward side of the cusp. C1, entering the cusp around 1 minute later, did not observe the high energy step anymore but a partial dispersion with a low energy cut-off reaching 100 eV. About 9 min later, C3 entered the cusp and observed a full ion dispersion from a few keV down to around 50 eV. The open-closed boundary, identified by electron precipitation, was initially moving equatorward at a rate of -0.43 degrees ILAT/minute at the beginning of the event and then slowed down to -0.16 degrees ILAT/minute, suggesting the erosion of the dayside magnetosphere under IMF Southward. This event is explained by the onset of dayside reconnection when the IMF turned southward; the step being the first signature of the reconnection that would then evolve as a full dispersion as reconnection goes on. We observed 1-3 keV ions near the open-closed boundary on the three spacecraft crossings that suggests a continuous reconnection during about 9 minutes.
| Type: | Article |
|---|---|
| Title: | Temporal evolution of a staircase ion signature observed by Cluster in the mid-altitude polar cusp |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1029/2005GL025598 |
| Publisher version: | http://dx.doi.org/10.1029/2005GL025598 |
| Language: | English |
| Additional information: | Copyright 2006 by the American Geophysical Union |
| Keywords: | Flux-transfer events, Interplanetary magnetic-field, Low-altitude observations, Magnetopause reconnection, Precipitation, Aurora, Edge |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery.ucl.ac.uk/id/eprint/162631 |
Loading...
Loading...Loading...| 1. |  United States | 9 |
| 2. |  Indonesia | 2 |
| 3. |  Japan | 1 |
| 4. |  China | 1 |
Archive Staff Only
 |
View Item |
