Coordinated ground-based, low altitude satellite and Cluster observations on global and local scales during a transient post-noon sector excursion of the magnetospheric cuspReport as inadecuate




Coordinated ground-based, low altitude satellite and Cluster observations on global and local scales during a transient post-noon sector excursion of the magnetospheric cusp - Download this document for free, or read online. Document in PDF available to download.

1 IRF - Swedish Institute of Space Physics Kiruna 2 FMI - Finnish Meteorological Institute 3 RAL - STFC Rutherford Appleton Laboratory 4 CESR - Centre d-étude spatiale des rayonnements 5 Department of Physics and Astronomy Calgary 6 Department of Physics Minneapolis 7 EISCAT Scientific Association Norway 8 University of Leicester 9 UiO - University of Oslo 10 Danish Meteorol. Inst. 11 The University of Sheffield Sheffield 12 Imperial College London 13 CETP - Centre d-étude des environnements terrestre et planétaires 14 Space Science Division 15 Univ. College 16 IFSI - Istituto di Fisica dello Spazio Interplanetaro 17 ARFL - Air Force Research Laboratory 18 APL - Johns Hopkins University Applied Physics Laboratory Laurel, MD 19 SRI - SRI International Menlo Park 20 Natl. Ctr. Atmosph. Res. 21 York University 22 LPCE - Laboratoire de physique et chimie de l-environnement 23 Univ. of Alberta 24 EOSTS - Ecole et Observatoire des sciences de la terre de Strasbourg 25 DSRI 26 University of Tromso

Abstract : On 14 January 2001, the four Cluster spacecraft passed through the northern magnetospheric mantle in close conjunction to the EISCAT Svalbard Radar ESR and approached the post-noon dayside magnetopause over Green-land between 13:00 and 14:00 UT. During that interval, a sudden reorganisation of the high-latitude dayside convection pattern occurred after 13:20 UT, most likely caused by a direction change of the Solar wind magnetic field. The result was an eastward and poleward directed flow-channel, as monitored by the SuperDARN radar network and also by arrays of ground-based magnetometers in Canada, Greenland and Scandinavia. After an initial eastward and later poleward expansion of the flow-channel between 13:20 and 13:40 UT, the four Cluster spacecraft, and the field line footprints covered by the eastward looking scan cycle of the Söndre Strömfjord incoherent scatter radar were engulfed by cusp-like precipitation with transient magnetic and electric field signatures. In addition, the EISCAT Svalbard Radar detected strong transient effects of the convection reorganisation, a poleward moving precipitation, and a fast ion flow-channel in association with the auroral structures that suddenly formed to the west and north of the radar. From a detailed analysis of the coordinated Cluster and ground-based data, it was found that this extraordinary transient convection pattern, indeed, had moved the cusp precipitation from its former pre-noon position into the late post-noon sector, allowing for the first and quite unexpected encounter of the cusp by the Cluster spacecraft. Our findings illustrate the large amplitude of cusp dynamics even in response to moderate solar wind forcing. The global ground-based data proves to be an invaluable tool to monitor the dynamics and width of the affected magnetospheric regions.





Author: H. J. Opgenoorth - M. Lockwood - D. Alcaydé - E. Donovan - M. J. Engebretson - A. P. Van Eyken - K. Kauristie - M. Lester - J. M

Source: https://hal.archives-ouvertes.fr/



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