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

[PEM12-P02] Spectroscopic measurement of ion upflow through Doppler shift of auroral 427.8-nm molecular nitrogen ion emission using a Fabry-Perot interferometer at Tromsoe, Norway: preliminary analysis

*Taiki Kikuchi¹, Kazuo Shiokawa¹, Shin-ichiro Oyama¹, Yasunobu Ogawa², Junichi Kurihara³ (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.National Institute of Polar Research, 3.Hokkaido Information University)

Keywords:sunlit aurora, ion upflow, molecular nitrogen ion, 427.8nm

Several satellite missions have reported existence of heavy ions which originated from Earth. Polar wind is one of the main pathways of these ions in the high latitude region. It is an ambipolar flow of plasma from ionosphere to magnetosphere. Before OGO6 discover the abrupt enhancement of N2+ densities in the high latitude region during magnetic storms, N2+ were considered not to exist in high altitude region due to their short lifetime. The OGO6 observation suggested that they are transported to high altitude thorough the upflow. Blue sunlit aurora seen before dawn has been considered as a consequence of the N2+ upflow. The wavelength observed from the ground become longer due to Doppler shift when N2+ is moving upward. Fabry-Perot interferometer (FPI) can measure velocity of ions from the amount of Doppler wavelength shift. We observed the auroral 427.8nm emission by FPI at Tromsoe, Norway, in the winter of 2022-2023. This is the first attempt to measure the Doppler shift of 427.8 nm emission to estimate the N2+ upflow velocity. In the presentation, we report result of the preliminary analysis of the interference fringes and address the issues that should be solved in future to obtain the Doppler shift.