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Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 26, 2485-2502, 2008
https://doi.org/10.5194/angeo-26-2485-2008
© Author(s) 2008. This work is distributed under
the Creative Commons Attribution 3.0 License.
 
20 Aug 2008
Ion-dispersion and rapid electron fluctuations in the cusp: a case study
J. Lunde1, S. C. Buchert2, Y. Ogawa3, M. Hirahara4, K. Seki5, Y. Ebihara6, T. Sakanoi7, K. Asamura8, M. Okada3, T. Raita9, and I. Häggström10 1Department of Physics and Technology, University of Tromsø, Norway
2Swedish Institute of Space Physics, University of Uppsala, Sweden
3National Institute of Polar Research (NIPR), Tokyo, Japan
4Department of Earth and Planetary Science, University of Tokyo, Japan
5STEL, Nagoya University, Japan
6IAR, Nagoya University, Japan
7PPARC, Tohoku University, Japan
8ISAS/JAXA, Sagamihara, Japan
9Sodankylä Geophysical Observatory, University of Oulu, Finland
10EISCAT Scientific Association, Kiruna, Sweden
Abstract. We present results from co-ordinated measurements with the low altitude REIMEI satellite and the ESR (EISCAT Svalbard Radar), together with other ground-based instruments carried out in February 2006. The results mainly relate to the dayside cusp where clear signatures of so-called ion-dispersion are seen in the satellite data. The cusp ion-dispersion is important for helping to understand the temporal and spatial structure of magnetopause reconnection. Whenever a satellite crosses boundaries of flux tubes or convection cells, cusp structures such as ion-dispersion will always be encountered. In our case we observed 3 distinct steps in the ion energy, but it includes at least 2 more steps as well, which we interpret as temporal features in relation to pulsed reconnection at the magnetopause. In addition, fast variations of the electron flux and energy occurring during these events have been studied in detail. The variations of the electron population, if interpreted as structures crossed by the REIMEI satellite, would map near the magnetopause to similar features as observed previously with the Cluster satellites. These were explained as Alfvén waves originating from an X-line of magnetic reconnection.

Citation: Lunde, J., Buchert, S. C., Ogawa, Y., Hirahara, M., Seki, K., Ebihara, Y., Sakanoi, T., Asamura, K., Okada, M., Raita, T., and Häggström, I.: Ion-dispersion and rapid electron fluctuations in the cusp: a case study, Ann. Geophys., 26, 2485-2502, https://doi.org/10.5194/angeo-26-2485-2008, 2008.
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