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Observations of an Auroral Streamer in a Double Oval Configuration : Volume 29, Issue 4 (27/04/2011)

By Amm, O.

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Book Id: WPLBN0003993062
Format Type: PDF Article :
File Size: Pages 16
Reproduction Date: 2015

Title: Observations of an Auroral Streamer in a Double Oval Configuration : Volume 29, Issue 4 (27/04/2011)  
Author: Amm, O.
Volume: Vol. 29, Issue 4
Language: English
Subject: Science, Annales, Geophysicae
Collections: Periodicals: Journal and Magazine Collection, Copernicus GmbH
Historic
Publication Date:
2011
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications

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Owen, C. J., Kauristie, K., Takada, T., Nakamura, R., Frey, H. U., Amm, O.,...Kuula, R. (2011). Observations of an Auroral Streamer in a Double Oval Configuration : Volume 29, Issue 4 (27/04/2011). Retrieved from http://ebook.worldlibrary.net/


Description
Description: Finnish Meteorological Institute, Arctic research unit, P.O. Box 503, 00101 Helsinki, Finland. During the late evening and night of 14 September 2004, the nightside auroral oval shows a distinct double oval configuration for several hours after a substorm onset at ~18:45 UT. This structure is observed both by the IMAGE satellite optical instruments focusing on the Southern Hemisphere, and by the MIRACLE ground-based instrument network in Scandinavia. At ~21:17 UT during the recovery phase of the substorm, an auroral streamer is detected by these instruments and the EISCAT radar, while simultaneously the Cluster satellites observe a bursty bulk flow in the conjugate portion of the plasma sheet in the magnetotail. Our combined data analysis reveals significant differences between the ionospheric equivalent current signature of this streamer within a double oval configuration, as compared to previously studied streamer events without such a configuration. We attribute these differences to the presence of an additional poleward polarization electric field between the poleward and the equatorward portions of the double oval, and show with a simple model that such an assumption can conceptually explain the observations. Further, we estimate the total current transferred in meridional direction by this recovery phase streamer to ~80 kA, significantly less than for previously analysed expansion phase streamer events. Both results indicate that the development of auroral streamers is dependent on the ambient background conditions in the magnetosphere-ionosphere system. The auroral streamer event studied was simultaneously observed in the conjugate Northern and Southern Hemisphere ionosphere.

Summary
Observations of an auroral streamer in a double oval configuration

Excerpt
Amm, O. and Kauristie, K.: Ionospheric signatures of bursty bulk flows, Surv. Geophys., 23, 1–32, 2002.; Amm, O. and Viljanen, A.: Ionospheric disturbance magnetic field continuation from the ground to the ionosphere using spherical elementary current systems, Earth, Planets Space, 51, 431– , 1999.; Amm, O., Pajunpää, A., and Brandström, U.: Spatial distribution of conductances and currents associated with a north-south auroral form during a multiple-substorm period, Ann. Geophys., 17, 1385–1396, doi:10.1007/s00585-999-1385-6, 1999.; Amm, O., Engebretson, M. J., Hughes, T., Newitt, L., Viljanen, A., and Watermann, J.: A traveling convection vortex event study: Instantaneous equivalent currents, estimation of field-aligned currents, and the role of induced currents, J. Geophys. Res., 107(A11), 1334, doi:10.1029/2002JA009472, 2002.; Angelopoulos, V., Baumjohann, W., Kennel, C. F., Coroniti, F. V., Kivelson, M. G., Pellat, R., Walker, R. J., Lühr, H., and Paschmann, G.: Bursty bulk flows in the inner central plasma sheet, J. Geophys. Res., 97, 4027–4039, 1992.; Angelopoulos, V., Kennel, C. F., Coroniti, F. V., Pellat, R., Kivelson, M. G., Walker, R. J., Russell, C. T., Baumjohann, W., Feldman, W. C., and.Gosling, J. T.: Statistical characteristics of bursty bulk flow events, J. Geophys. Res., 99, 21257– , 1994.; Balogh, A., Carr, C. M., Acuña, M. H., Dunlop, M. W., Beek, T. J., Brown, P., Fornacon, K.-H., Georgescu, E., Glassmeier, K.-H., Harris, J., Musmann, G., Oddy, T., and Schwingenschuh, K.: The Cluster Magnetic Field Investigation: overview of in-flight performance and initial results, Ann. Geophys., 19, 1207–1217, doi:10.5194/angeo-19-1207-2001, 2001.; Baumjohann, W., Paschmann, G., and Lühr, H.: Characteristics of high-speed ion flows in the plasma sheet, J. Geophys. Res., 95, 3801–3809, 1990.; Chen, C. X. and Wolf, R. A.: Interpretation of high-speed flows in the plasma sheet, J. Geophys. Res., 98, 21409–21419, 1993.; Chen, C. X. and Wolf, R. A.: Theory of thin-filament motion in Earth's magnetotail and its application to bursty bulk flows, J. Geophys. Res., 104, 14613–14626, 1999.; Dunlop, M. W., Balogh, A., Glassmeier, K.-H., and Robert, P.: Four-point Cluster application of magnetic field analysis tools: The Curlometer, J. Geophys. Res., 107(A11), 1384, doi:10.1029/2001JA005088, 2002.; Folkestad, K., Hagfors, T., and Westerlund, S.: EISCAT: An updated description of technical characteristics, Radio Sci., 18, 867– , 1983.; Elphinstone, R. D., Murphree, J. S., Hearn, D. J., Cogger, L. L., Sandahl, I., Newell, P. T., Klumpar, D. M., Ohtani, S., Sauvaud, J. A., and Potemra, T. A.: The double oval UV auroral distribution. 1: Implications for the mapping of auroral arcs, J. Geophys. Res., 100, 12075– , 1995.; Escoubet, C. P., Fehringer, M., and Goldstein, M.: Introduction: The Cluster mission, Ann. Geophys., 19, 1197–1200, doi:10.5194/angeo-19-1197-2001, 2001.; Forsyth, C., Lester, M., Cowley, S. W. H., Dandouras, I., Fazakerley, A. N., Fear, R. C., Frey, H. U., Grocott, A., Kadokura, A., Lucek, E., R�me, H., Milan, S. E., and Watermann, J.: Observed tail current systems associated with bursty bulk flows and auroral streamers during a period of multiple substorms, Ann. Geophys., 26, 167–184, doi:10.5194/angeo-26-167-2008, 2008.; Gjerloev, J. W., Hoffman, R. A., Sigwarth, J. B., Frank, L. A., and Baker, J. B. H.: Typical auroral substorm: A bifurcated oval, J. Geophys. Res., 113, A03211, doi:10.1029/2007JA012431, 2008.; Henderson, M. G., Reeves, G. D., and Murphree, J.

 

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