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Magnetospheric response and reconfiguration times following IMF By reversals

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journal contribution
posted on 09.03.2017, 10:30 by P. Tenfjord, N. Østgaard, R. Strangeway, S. Haaland, K. Snekvik, K. M. Laundal, J. P. Reistad, S. E. Milan
The interaction between the interplanetary magnetic field (IMF) and the geomagnetic field at the dayside magnetopause leads to transfer of momentum and energy which changes the magnetospheric configuration, but only after a certain time. In this study we quantify this time, to advance our understanding of the causes for the delayed response of the magnetosphere. We study the response and reconfiguration time of the inner magnetosphere to IMF By reversals. A superposed epoch analysis of magnetic field measurements from four Geostationary Operational Environmental Satellite spacecraft at different local times both for negative to positive IMF By reversals and for positive to negative reversals is presented. The magnetospheric response time at geosynchronous orbit to the sudden change of IMF By is less than 15 (∼10) min from the bow shock (magnetopause) arrival time, while the reconfiguration time is less than 46 (∼41) min. These results are consistent with a By component induced on closed magnetic field lines due to the asymmetric loading of flux following asymmetric dayside reconnection when IMF By≠0. Our results also confirm our earlier studies that nightside reconnection is not required for generating a By component on closed field lines.


his study was supported by the Research Council of Norway/CoE under contract 223252/F50. S.E. Milan was supported by STFC grant ST/K001000/1. We acknowledge the use of NASA/GSFC's Space Physics Data Facility for OMNI data. For the ground magnetometer data we gratefully acknowledge the following: Intermagnet; USGS, Jeffrey J. Love; CARISMA, PI Ian Mann; CANMOS; the S-RAMP Database, PI K. Yumoto and K. Shiokawa; the SPIDR database; AARI, PI Oleg Troshichev; the MACCS program, PI M. Engebretson, Geomagnetism Unit of the Geological Survey of Canada; GIMA; MEASURE, UCLA IGPP, and Florida Institute of Technology; SAMBA, PI Eftyhia Zesta; 210 Chain, PI K. Yumoto; SAMNET, PI Farideh Honary; the institutes who maintain the IMAGE magnetometer array, PI Eija Tanskanen; PENGUIN; AUTUMN, PI Martin Connors; DTU Space, PI Juergen Matzka; South Pole and McMurdo Magnetometer, PIs Louis J. Lanzarotti and Alan T. Weatherwax; ICESTAR; RAPIDMAG; PENGUIN; British Antarctic Survey; McMac, PI Peter Chi; BGS, PI Susan Macmillan; Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN); GFZ, PI Juergen Matzka; MFGI, PI B. Heilig; IGFPAS, PI J. Reda; University of L'Aquila, PI M. Vellante; and SuperMAG, PI Jesper W. Gjerloev.



Journal of Geophysical Research: Space Physics, 2017, 122, 417–431

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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Journal of Geophysical Research: Space Physics


American Geophysical Union (AGU), Wiley





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The OMNI and GOES data are found here: http://cdaweb.gsfc.nasa.gov. SuperMAG data are available here: http://supermag.jhuapl.edu/. Scientists interested in other data used should contact the corresponding author.