Japan Geoscience Union Meeting 2016

Presentation information

Oral

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM18] Dynamics in magnetosphere and ionosphere

Wed. May 25, 2016 10:45 AM - 12:15 PM 103 (1F)

Convener:*Tomoaki Hori(Institute for Space-Earth Environmental Research, Nagoya University), Yoshimasa Tanaka(National Institute of Polar Research), Aoi Nakamizo(Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology), Mitsunori Ozaki(Faculty of Electrical and Computer Engineering, Institute of Science and Engineering, Kanazawa University), Shin'ya Nakano(The Institute of Statistical Mathematics), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Chair:Yukinaga Miyashita(Institute for Space-Earth Environmental Research, Nagoya University), Keisuke Hosokawa(Department of Communication Engineering and Informatics, University of Electro-Communications), Yoshimasa Tanaka(National Institute of Polar Research), Shin'ya Nakano(The Institute of Statistical Mathematics)

11:00 AM - 11:15 AM

[PEM18-02] Stable sun-aligned arcs equatorward of the cusp

*Satoshi Taguchi1, Keisuke Hosokawa2, Yasunobu Ogawa3 (1.Department of Geophysics, Kyoto University, 2.Department of Communication Engineering and Informatics, University of Electro-Communications, 3.National Institute of Polar Research)

Keywords:aurora, cusp, plasma convection

A well-established feature of the aurora in the cusp is a transient poleward-moving auroral form. The initial brightening of this aurora occurs near the equatorward edge of the persistent east-west aligned aurora, and then the auroral form moves poleward. This aurora form often occurs at several minute intervals. When compared with this kind of active features, the aurora equatorward of the cusp may be thought to be generally quiet. In this study, we focus on auroral arcs that sometimes appear equatorward of the persistent cusp. By examining auroral image data obtained at wavelengths of 557.7 nm and 630.0 nm by an all-sky imager at Longyearbyen, Svalbard, we found several events in which sun-aligned arcs exist stably equatorward of the cusp in the noon sector. The sun-aligned arcs, which range between ~70 and ~76 MLAT, move from the postnoon to the noon sector slowly. The lifetime of the sun-aligned arcs is ~15 min or longer, which is much longer than that of the transient moving auroral form. The poleward portion of this arc, which is located at ~76 MLAT, is measured by the EISCAT Svalbard Radar. Simultaneous observations from the EISCAT Svalbard Radar and the all-sky imager show that fast plasma flow exists in the region of the auroral arc. Multiple sun-aligned arcs can also be observed. We discuss the spatial distribution of the plasma flow associated with the stable sun-aligned arcs equatorward of the cusp, and interpret the flow distribution in terms of temporal variations in the duskside convection cell.