SM13F-4230:
Ground and satellite observations of multiple sun-aligned auroral arcs on the duskside
Monday, 15 December 2014
Keisuke Hosokawa1, Romain Maggiolo2, Yongliang Zhang3, Robert C Fear4, Dominique Fontaine5, Judy A Cumnock6, Anita Kullen7, Stephen E Milan4, Alexander Kozlovsky8, Marius Echim9 and Kazuo Shiokawa10, (1)University of Electro-Communications, Tokyo, Japan, (2)Belgian Institute for Space Aeronomy, Brussels, Belgium, (3)The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (4)University of Leicester, Leicester, United Kingdom, (5)CNRS, Paris Cedex 16, France, (6)University of Texas at Dallas, Richardson, TX, United States, (7)EES KTH Stockholm, Stockholm, Sweden, (8)Sodankylä Geophysical Observatory, Sodankylä, Finland, (9)Institute of Space Sciences, Bucharest, Romania, (10)Nagoya University, Solar terrestrial Environment Laboratory, Nagoya, Japan
Abstract:
Sun-aligned auroral arcs (SAAs) are one of the outstanding phenomena in the high-latitude region during periods of northward interplanetary magnetic field (IMF). Smaller scale SAAs tend to occur either in the duskside or dawnside of the polar cap and are known to drift in the dawn-dusk direction depending on the sign of the IMF By. Studies of SAAs are of particular importance because they represent dynamical characteristics of their source plasma in the magnetosphere, for example in the interaction region between the solar wind and magnetosphere or in the boundary between the plasma sheet and tail lobe. To date, however, very little has been known about the spatial structure and/or temporal evolution of the magnetospheric counterpart of SAAs. In order to gain more comprehensive understanding of the field-aligned plasma transport in the vicinity of SAAs, we have investigated an event of SAAs on November 10, 2005, during which multiple SAAs were detected by a ground-based all-sky camera at Resolute Bay, Canada. During this interval, several SAAs were detached from the duskside oval and moved poleward. The large-scale structure of these arcs was visualized by space-based imagers of TIMED/GUVI and DMSP/SSUSI. In addition to these optical observations, we employ the Cluster satellites to reveal the high-altitude particle signature corresponding to the small-scale SAAs. The ionospheric footprints of the 4 Cluster satellites encountered the SAAs sequentially and observed well correlated enhancements of electron fluxes at weak energies (< 1 keV). The Cluster satellites also detected signatures of upflowing beams of ions and electrons in the vicinity of the SAAs. This implies that these ions and electrons were accelerated upward by a quasi-stationary electric field existing in the vicinity of the SAAs and constitute a current system in the magnetosphere-ionosphere coupling system. Ionospheric convection measurement from one of the SuperDARN radars shows an indication that the SAAs are embedded in the lobe cell during northward IMF conditions. In the presentation, we will show the results of detailed comparison between the ground-based radio and optical signatures of the SAAs and those obtained by the Cluster spacecraft at magnetospheric altitudes.
