11:15 〜 11:30
[PEM10-03] Possible Observations of Plasmaspheric O+ from ICON EUV
キーワード：Plasmasphere, ICON, coupling, observations, ultraviolet, spectrometry
O+ and O++ are tertiary components of Earth’s plasmasphere, which forms a torus extending from roughly 2-5 Earth radii. Unlike the dominant H+ and He+, the oxygen species undergo strong variation due to transport from the ionosphere and occasionally form a dense torus. Additional measurements of plasmaspheric O+ are needed to distinguish between competing hypotheses for the mechanism of this ionosphere-magnetosphere coupling. The Ionospheric Connection Explorer (ICON) carries an extreme-ultraviolet (EUV) spectrometer, which measures the structure of the F-region ionosphere using O+ airglow at 61.6 and 83.4 nm. The 83.4 nm photons are resonantly scattered by O+ and O++; this band has been proposed for plasmasphere observations, with an estimated signal of ~100 mR. On 16 May 2022, ICON observed an 83.4 nm signal of ~2-3 R while performing a scan of the moon as part of its calibration sequence. Analysis has confirmed that the EUV field-of-view did not include any illuminated ionosphere, suggesting that the signal is from the plasmasphere. We examine this ICON lunar calibration and others, seeking to identify elements of possible plasmaspheric structure imaged by ICON.