Exterior and interior polar cusps: Observations from Hawkeye

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dc.contributor.authorChen, S.-H.
dc.contributor.authorBoardsen, S. A.
dc.contributor.authorFung, S. F.
dc.contributor.authorGreen, J. L.
dc.contributor.authorKessel, R. L.
dc.contributor.authorTan, Lun C.
dc.contributor.authorEastman, T. E.
dc.contributor.authorCraven, J. D.
dc.date.accessioned2021-07-30T17:31:07Z
dc.date.available2021-07-30T17:31:07Z
dc.date.issued1997-06-01
dc.description.abstractHawkeye plasma, magnetic field, and plasma wave instruments directly sampled the throat of the northern polar cusp as the orientation of the interplanetary magnetic field (IMF) changed from southward to northward on July 3, 1974. Two distinct regions in the polar cusp were identified based on magnetic field, plasma flow and magnetic and electric noise: the interior and exterior cusps. The observations show highly variable flows in the exterior portion of the cusp and constantly strong dawn-dusk flows in the interior portion during periods of strong IMF By component. Results of a minimum variance analysis of the magnetic field at each cusp interface crossing provides evidence that the magnetopause surface normal deviated highly from empirical models. During intervals of relatively steady solar wind dynamic pressure, the motion of the cusp relative to the slow moving spacecraft was modulated by the varying IMF clock angle as observed by IMP 8 in the upstream solar wind. The motion did not show a correlation with internal processes monitored by the AE index. We propose that observed plasma flow patterns and cusp motion are results of reconnection between the IMF and the magnetospheric magnetic field. Flow velocity observed in the interior cusp is consistent with stress balance for a reconnection process. This unique interval provides an opportunity for detailed studies of the plasma, magnetic field, and plasma wave properties in both the exterior and interior cusp.en_US
dc.description.sponsorshipWe thank the NSSDC for supplying the Hawk- eye and IMP-8 data. We thank J. Van Allen, A. Lazarus, and R. Lepping for making the Hawkeye, IMP 8 plasma and IMP 8 mag- netic field data, respectively, available to NSSDC. The author S. H. C. thanks the support from the National Research Council Associateship Program, National Academy of Science. The research conducted at the Space Science Data Operations Office, Goddard Space Flight Center was performed under the auspices of the National Aeronautics and Space Administration. The work at the Hughes STX Corporation was performed under NASA grant NAS5-97059. The work at the Univer- sity of Maryland was performed under NSF grant ATM-9411766. The work at the University of Alaska was funded by NASA grant NAGW- 3441.en_US
dc.description.urihttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/97JA00743en_US
dc.format.extent13 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2nwmo-tes5
dc.identifier.citationChen, S.-H. et al.; Exterior and interior polar cusps: Observations from Hawkeye; Journal of Geophysical Research : Space Physics, 102, A6, p 11335-11347, 1 June, 1997; https://doi.org/10.1029/97JA00743en_US
dc.identifier.urihttps://doi.org/10.1029/97JA00743
dc.identifier.urihttp://hdl.handle.net/11603/22228
dc.language.isoen_USen_US
dc.publisherAmerican Geophysical Unionen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Goddard Planetary Heliophysics Institute (GPHI)
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
dc.rightsPublic Domain Mark 1.0*
dc.rightsThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
dc.rights.urihttp://creativecommons.org/publicdomain/mark/1.0/*
dc.titleExterior and interior polar cusps: Observations from Hawkeyeen_US
dc.typeTexten_US

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