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Coordinated interhemispheric SuperDARN radar observations of the ionospheric response to flux transfer events observed by the Cluster spacecraft at the high-latitude magnetopause

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posted on 2017-01-25, 17:19 authored by J. A. Wild, S. E. Milan, S. W. H. Cowley, M. W. Dunlop, C. J. Owen, J. M. Bosqued, M. G. G. T. Taylor, J. A. Davies, M. Lester, N. Sato, A. S. Yukimatu, A. N. Fazakerley, A. Balogh, H. Rème
At 10:00 UT on 14 February 2001, the quartet of ESA Cluster spacecraft were approaching the Northern Hemisphere high-latitude magnetopause in the post-noon sector on an outbound trajectory. At this time, the interplanetary magnetic field incident upon the dayside magnetopause was oriented southward and duskward (BZ negative, BY positive), having turned from a northward orientation just over 1 hour earlier. As they neared the magnetopause the magnetic field, electron, and ion sensors on board the Cluster spacecraft observed characteristic field and particle signatures of magnetospheric flux transfer events (FTEs). Following the traversal of a boundary layer and the magnetopause, the spacecraft went on to observe further signatures of FTEs in the magnetosheath. During this interval of ongoing pulsed reconnection at the high-latitude post-noon magnetopause, the footprints of the Cluster spacecraft were located in the fields-of-view of the SuperDARN Finland and Syowa East radars located in the Northern and Southern Hemispheres, respectively. This study extends upon the initial survey of Wild et al. (2001) by comparing for the first time in situ magnetic field and plasma signatures of FTEs (here observed by the Cluster 1 spacecraft) with the simultaneous flow modulations in the conjugate ionospheres in the two hemispheres. During the period under scrutiny, the flow disturbances in the conjugate ionospheres are manifest as classic "pulsed ionospheric flows" (PIFs) and "poleward moving radar auroral forms" (PMRAFs). We demonstrate that the ionospheric flows excited in response to FTEs at the magnetopause are not those expected for a spatially limited reconnection region, somewhere in the vicinity of the Cluster 1 spacecraft. By examining the large- and small-scale flows in the high-latitude ionosphere, and the inter-hemispheric correspondence exhibited during this interval, we conclude that the reconnection processes that result in the generation of PIFs/PMRAFs must extend over many (at least 4) hours of magnetic local time on the pre- and post-noon magnetopause.

Funding

During the course of this study Drs. Jackie Davies and James Wild were supported by PPARC grant number PPA/G/O/2001/0014. Prof. Stan Cowley was supported by a PPARC Senior Fellowship (grant number PPAN/N/S/2000/00197). Prof. N. Sato and Dr. A. S. Yukimatu were supported by a JSPS grant for scientific research (grant number A:11304029). The CUTLASS HF radars are deployed and operated by the University of Leicester, and are jointly funded by the UK Particle Physics and Astronomy Research Council (grant number PPA/R/R/1997/00256), the Finnish Meteorological Institute, and the Swedish Institute of Space Physics. The Syowa HF radars are deployed and operated by National Institute of Polar Research, and funded by the Ministry of Education, Culture, Sports, Science and Technology of Japan. We also thank all those SuperDARN PIs who provided radar data and Norman Ness and the ACE Science Center for providing the ACE magnetic field data presented in Fig. 3

History

Citation

Annales Geophysicae, 2003, 21 (8), pp. 1807-1826 (20)

Author affiliation

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

Version

  • VoR (Version of Record)

Published in

Annales Geophysicae

Publisher

European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)

issn

0992-7689

eissn

1432-0576

Acceptance date

2003-03-25

Copyright date

2003

Available date

2017-01-25

Publisher version

http://www.ann-geophys.net/21/1807/2003/angeo-21-1807-2003.html

Language

en