Analysis of plasmaspheric plumes: CLUSTER and IMAGE observations
1Belgian Institute for Space Aeronomy (IASB-BIRA), Brussels, Belgium
2Laboratoire de Physique et Chimie de l’Environnement (LPCE), CNRS and University of Orléans, Orléans, France
3Marshall Space Flight Center (MSFC), NASA, Huntsville, Alabama, USA
4Center for Space Radiation (CSR), Louvain la Neuve, Belgium
5Lunar and Planetary Laboratory (LPL), University of Arizona, Tucson, Arizona, USA
6Centre d’Etude Spatiale des Rayonnements (CESR), CNRS, Toulouse, France
7Space Science Center (SSC), University of New Hampshire, Durham, New Hampshire, USA
8Space Sciences Division (SSTD), Rutherford Appleton Laboratory (RAL), Chilton, Didcot, Oxfordshire, UK
9Research and Scientific Support Department (RSSD), ESTEC-ESA, Noordwijk, The Netherlands
10Centre d’étude des Environnements Terrestre et Planétaires (CETP), CNRS, Vélizy, France
11Swedish Institute of Space Physics (IRFU), Uppsala division, Uppsala, Sweden
Abstract. Plasmaspheric plumes have been routinely observed by CLUSTER and IMAGE. The CLUSTER mission provides high time resolution four-point measurements of the plasmasphere near perigee. Total electron density profiles have been derived from the electron plasma frequency identified by the WHISPER sounder supplemented, in-between soundings, by relative variations of the spacecraft potential measured by the electric field instrument EFW; ion velocity is also measured onboard these satellites. The EUV imager onboard the IMAGE spacecraft provides global images of the plasmasphere with a spatial resolution of 0.1 RE every 10 min; such images acquired near apogee from high above the pole show the geometry of plasmaspheric plumes, their evolution and motion. We present coordinated observations of three plume events and compare CLUSTER in-situ data with global images of the plasmasphere obtained by IMAGE. In particular, we study the geometry and the orientation of plasmaspheric plumes by using four-point analysis methods. We compare several aspects of plume motion as determined by different methods: (i) inner and outer plume boundary velocity calculated from time delays of this boundary as observed by the wave experiment WHISPER on the four spacecraft, (ii) drift velocity measured by the electron drift instrument EDI onboard CLUSTER and (iii) global velocity determined from successive EUV images. These different techniques consistently indicate that plasmaspheric plumes rotate around the Earth, with their foot fully co-rotating, but with their tip rotating slower and moving farther out.
Darrouzet, F., De Keyser, J., Décréau, P. M. E., Gallagher, D. L., Pierrard, V., Lemaire, J. F., Sandel, B. R., Dandouras, I., Matsui, H., Dunlop, M., Cabrera, J., Masson, A., Canu, P., Trotignon, J. G., Rauch, J. L., and André, M.: Analysis of plasmaspheric plumes: CLUSTER and IMAGE observations, Ann. Geophys., 24, 1737-1758, doi:10.5194/angeo-24-1737-2006, 2006.