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Ann. Geophys., 24, 203-214, 2006
www.ann-geophys.net/24/203/2006/
© European Geosciences Union 2006

Ionospheric characteristics of the dusk-side branch of the two-cell aurora

J.-H. Shue¹, P. T. Newell², K. Liou², C.-I. Meng², M. R. Hairston³, and F. J. Rich^4
1Institute of Space Science and Dept. of Atmospheric Sciences, National Central University, Jhongli, Taoyuan 32001, Taiwan
²The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
³Center of Space Science, University of Texas in Dallas, POB 830688, Richardson, TX 75083, USA
⁴Air Force Research Laboratory/VSBXP, 29 Randolph Road, Hanscom AFB, MA 01731, USA

Abstract. The two-cell aurora is characterized by azimuthally elongated regions of enhanced auroral brightness over extended local times in the dawn and dusk sectors. Its association with the convection, particle precipitation, and field-aligned currents under various phases of substorms has not been fully understood. With Polar Ultraviolet Imager auroral images in conjunction with Defense Meteorological Satellite Program (DMSP) F12 spacecraft on the dusk-side branch of the two-cell aurora, we are able to investigate an association of the auroral emissions with the electric fields, field-aligned currents, and energy flux of electrons. Results show that the substorm expansion onset does not significantly change the orientation of the dusk-side branch of the two-cell aurora. Also, the orientation of the magnetic deflection vector produced by the region 1 field-aligned current changed from 73±1° to the DMSP trajectory during the substorm growth phase, to 44±6° to the DMSP trajectory during the substorm expansion phase. With a comparison between the orientation of the dusk-side branch of the two-cell aurora and the orientation of the magnetic deflection vector, it is found that the angular difference between the two orientations is 28±5° during the substorm growth phase, and 13±6° during the substorm expansion phase.

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Citation: Shue, J.-H., Newell, P. T., Liou, K., Meng, C.-I., Hairston, M. R., and Rich, F. J.: Ionospheric characteristics of the dusk-side branch of the two-cell aurora, Ann. Geophys., 24, 203-214, 2006.   Bibtex   EndNote   Reference Manager