[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-P15] Initial results of SDI-3D thermospheric measurements in 2024-2025 winter

*Shin-ichiro Oyama^1,2, Mark Conde³, Heikki Vanhamaki⁴, Habtamu Tesfaw⁴, Lei Cai⁴, Anita T Aikio⁴, Ilkka I Virtanen⁴, Keisuke Hosokawa⁵, Yasunobu Ogawa², Tero Raita⁶, Kylee Branning³, Mamoru Ishii^1,7, Aaron Ridley⁸ (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.National Institute of Polar Research, 3.Geophysical Institute, University of Alaska Fairbanks, 4.University of Oulu, 5.The University of Electro-Communications, 6.Sodankylä Geophysical Observatory, University of Oulu, 7.National Institute of Information and Communications Technology, 8.University of Michigan)

Keywords:high latitude, Thermosphere, Ionosphere, Scanning Doppler Imager, EISCAT

Aurorae and ionospheric plasma flows exhibit intricate, fine structures that vary temporally and spatially superimposing on the global-scale structure. These fine structures represent the true form of the magnetosphere-ionosphere coupled system and relate to crucial fact in advancing our understanding of energy dissipation processes in the partially ionized plasma or ionosphere at high latitudes. One of the primary research activities of the EISCAT_3D and optical camera network developed in Northern Scandinavia is to conduct observational studies of these fine structures.

A comprehensive understanding of energy dissipation processes in the polar upper atmosphere is contingent upon two primary aspects. The first involves advancing research on particle collision processes through the examination of individual and simultaneous measurements of ionospheric plasma and thermospheric neutrals. This approach will enhance our comprehension of how fine structures of aurora and ionospheric plasma flow impact the thermosphere. The second aspect focuses on conducting wide-area two-dimensional observations of the thermosphere to thoroughly examine both its large-scale structure, characterized by tidal motions and ion drag resulting from ionospheric plasma convection, as well as the delay and displacement of temporal and spatial variations associated with inertia and advection of the thermosphere. Previously, there is no observational system to comprehensively address these two aspects. In 2018, an international project (SDI-3D) was established with researchers from Japan, the United States, and Finland. They developed a comprehensive observation system utilizing three large optical interferometers (SDI-3D) and a next-generation ionospheric radar (EISCAT_3D) to monitor the thermosphere and ionosphere in Northern Scandinavia. Along with an optical camera network already exists in the area, this system provides the world's first capability of simultaneously measuring fine structures of the thermosphere, ionosphere, and aurora in the wide area.

The poster presentation will report findings from the 2024-2025 winter season, address methodological challenges encountered from initial analysis, and discuss observational strategies for the subsequent season.