Title: Poleward expansion of the auroral oval and associated phenomena in the magnetotail during auroral substorms, 2
Abstract: Journal of Geophysical Research (1896-1977)Volume 76, Issue 34 p. 8241-8257 Poleward expansion of the auroral oval and associated phenomena in the magnetotail during auroral substorms, 2 E. W. Hones Jr., E. W. Hones Jr.Search for more papers by this authorS.-I. Akasofu, S.-I. AkasofuSearch for more papers by this authorS. J. Bame, S. J. BameSearch for more papers by this authorS. Singer, S. SingerSearch for more papers by this author E. W. Hones Jr., E. W. Hones Jr.Search for more papers by this authorS.-I. Akasofu, S.-I. AkasofuSearch for more papers by this authorS. J. Bame, S. J. BameSearch for more papers by this authorS. Singer, S. SingerSearch for more papers by this author First published: 1 December 1971 https://doi.org/10.1029/JA076i034p08241Citations: 37AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract In the magnetotail at the distance of the Vela satellite orbits (r∼17 to 20 RE) the plasma sheet becomes thin early in a polar magnetic substorm and then becomes thick again late in the substorm. Also, the thinning process consists not only of a reduction in the thickness of the plasma-containing region but also of a decrease of the plasma energy density throughout the region, except perhaps very near the neutral sheet. In this paper the process of plasma-sheet thinning is examined in substorms for which all-sky photographs as well as ground-based magnetograms were available. Thus the thinning process could be correlated with features of both the auroral substorm and the polar magnetic substorm. The following phenomena usually begin simultaneously to within the few-minutes accuracy of the timing of the measurements: (a) plasma-sheet thinning, (b) development of negative magnetic bays in the nightside auroral oval (independent of whether these develop rapidly or gradually), (c) development of positive magnetic bays at nightside low-latitude stations, and (d) brightening and poleward motion of auroras in the nightside auroral oval. These results are entirely consistent with, although more detailed and precise, than our earlier reports that plasma-sheet thinning and negative magnetic-bay development in the auroral zone proceed together. This study does not help to resolve the presently existing controversy as to whether or not some magnetospheric substorms have a 'development phase' preceding the classical substorm 'onset' features, because none of the substorms examined seemed clearly to have a 'development phase.' After its onset, plasma-sheet thinning continues, often for half an hour to an hour, as the aurora moves poleward. The poleward motion of the aurora may be indicative of the development of a new 'hot' plasma sheet within the old 'cool' plasma sheet as the latter becomes thin. References Akasofu, S.-I., Polar and Magnetospheric Substoms, 20, 27, D. Reidel, Dordrecht, Netherlands, 1968. Akasofu, S.-I., E. W. Hones Jr., S. Singer, Impulsive energetic electron fluxes in the distant magnetotail associated with the onset of magnetospheric substorms, J. Geophys. Res., 76, 6976, 1971. Axford, W. I., Magnetospheric convection, Rev. Geophys. Space Phys., 7, 421, 1969. Hirasawa, T., andK. Kaminuma, Space-time variation of aurora and geomagnetic disturbances— Auroral observations at Syowa station in Antarctica—1967–1968, JARE Sci. Rep.,Sci. Rep. Ser. A, no. 8,Appendix 2, p. 1,Aeronomy, Department of Polar Research,National Science Museum, Tokyo,March1970. Hones Jr., E. W., Magnetotail plasma and magnetospheric substorms, Particles and Fields in the Magnetosphere B. M. McCormac, 24, D. Reidel, Dordrecht, Netherlands, 1970a. Hones Jr., E. W., Experimental observations in the magnetotail during an interplanetary disturbance, Intercorrelated Satellite Observations Related to Solar Events V. Manno, D. E. Page, 299, D. Reidel, Dordrecht, Netherlands, 1970b. Hones Jr., E. W., J. R. Asbridge, S. J. Bame, I. B. Strong, Outward flow of plasma in the magnetotail following geomagnetic bays, J. Geophys. Res., 72, 5879, 1967. Hones Jr., E. W., S.-I. Akasofu, P. Perreault, S. J. Bame, S. Singer, Poleward expansion of the auroral oval and associated phenomena in the magnetotail during auroral substorms, 1, J. Geophys. Res., 75, 7060, 1970. Hones Jr., E. W., J. R. Asbridge, S. J. Bame, Time-variations of the magnetotail plasma sheet at 18 Redetermined from concurrent observations by a pair of Vela satellites, J. Geophys. Res., 76, 4402, 1971a. Hones Jr., E. W., R. H. Karas, L. J. Lanzerotti, S.-I. Akasofu, Magnetospheric substorms on September 14, 1968, J. Geophys. Res., 76, 6765, 1971b. Hones Jr., E. W., S. Singer, L. J. Lanzerotti, J. D. Pierson, T. J. Rosenberg, Magnetospheric substorm of August 25–26, 1967, J. Geophys. Res., 76, 2977, 1971c. McPherron, R. L., Growth phase of magnetospheric substorms, J. Geophys. Res., 75, 5592, 1970. Russell, C. T., K. I. Brody, Some remarks on the position and shape of the neutral sheet, J. Geophys. Res., 72, 6104, 1967. Citing Literature Volume76, Issue34Space Physics1 December 1971Pages 8241-8257 ReferencesRelatedInformation
Publication Year: 1971
Publication Date: 1971-12-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 39
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