Japan Geoscience Union Meeting 2019

Presentation information

[J] Oral

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

[P-EM16] Physics and Chemistry in the Atmosphere and Ionosphere

Wed. May 29, 2019 9:00 AM - 10:30 AM A03 (TOKYO BAY MAKUHARI HALL)

convener:Yuichi Otsuka(Institute for Space-Earth Environmental Research, Nagoya University), Takuya Tsugawa(National Institute of Information and Communications Technology), Seiji Kawamura(National Institute of Information and Communications Technology), Chairperson:Mitsumu Ejiri(国立極地研究所), Yuichi Otsuka

9:30 AM - 9:45 AM

[PEM16-03] Spatial distribution of the polar thermospheric wind acceleration and importance of the 2D measurement

*Shin-ichiro Oyama1,2,3, Anita Aikio2, Mark G Conde4, Heikki Vanhamaki2, Ilkka Virtanen2, Thomas Ulich5, Urban Brandstrom6, Pekka Verronen7, Monika Andersson7, Niilo Kalakoski7, Lassi Roininen8, Sari Lasanen8, Abiyot Workayehu2, Kazuo Shiokawa1, Heqiucen XU1, Mamoru Ishii9, Masafumi Hirahara1, Takeshi Sakanoi10, Masato Kagitani10, Juha Sorri5, Tomi Teppo5, Yoshimasa Tanaka3, Christopher Fallen4, Brenton J Watkins4, Mikko Orispaa5, Yasunobu Ogawa3, Lei Cai11, Esa Turunen5, Kirsti Kauristie7, Takuo T. Tsuda12, Junichi Kurihara13 (1.Institute for Space-Earth Environmental Research, Nagoya University, Japan, 2.University of Oulu, Finland, 3.National Institute of Polar Research, Japan, 4.Geophysical Institute, University of Alaska Fairbanks, US, 5.Sodankyla Geophysical Observatory, University of Oulu, Finland, 6.The Swedish Institute of Space Physics (IRF), Sweden, 7.Finnish Meteorological Institute, Finland, 8.Lappeenranta-Lahti University of Technology, Finland, 9.National Institute of Information and Communications Technology, Japan, 10.Tohoku University, Japan, 11.KTH Royal Institute of Technology, Sweden, 12.The University of Electro-Communications, 13.Hokkaido University)

Keywords:aurora, substorm, Thermosphere, Ionosphere

Understanding the flow of energy and mass throughout the magnetosphere-ionosphere-thermosphere coupled system is a fundamental goal of solar-terrestrial physics. Since substantial energy accumulated in the substorm growth phase in the magnetospheric tail flows into the polar ionosphere immediately after the substorm onset, investigating the energy dissipation process at high latitudes around the time of substorm onset can contribute significantly to achieving that objective. The energy dissipation generates acceleration and heating of the ionosphere and thermosphere, but this might occur not only near aurora but also far from it by hundreds kilometers equatorward. We analyzed ionospheric and thermospheric measurements in the northern Scandinavian area (65-80 N) during periods of considerably low geomagnetic activity but with some aurorae above Svalbard (75-80 N). Thermospheric winds measured with a Fabry-Perot interferometer (FPI; 630.0 nm) at Tromsø, Norway (69.6 N) showed westward accelerations coinciding with auroral brightening at the Svalbard area at the dusk sector though the relative distance from Tromsø to the aurora was 200-500 km in some cases. Moving into the dawn sector with the earth’s rotation, the acceleration direction turned to southeastward through stagnation area or period seen at magnetic local midnight. The acceleration pattern well represents thermospheric responses to the ionospheric convection, but of particular interest is its location, in which the thermospheric wind have been obtained at the sub-auroral region far from the main auroral oval. In this analysis, we cannot infer to horizontal patterns of the wind acceleration because we have only a point measurement from the Tromsø FPI. While this result suggests the importance of two-dimensional measurements of ionosphere and the thermosphere, we need a new configuration of the observation network to infer horizontal winds and accelerations. In this presentation, we will introduce “SDI-3D” project, which aims at developing 3 Scanning Doppler Imagers (SDIs) and deploying them at the same area as for the EISCAT_3D, which may start in operation in 2022.