[P-EM11] New frontier: Observations of the middle and upper atmospheres from ISS

[PEM11-13] 630-nm airglow imaging observations of plasma bubbles from the International Space Station

*Yuichi OTSUKA¹, Takanori YAMADA¹, Takeshi SAKANOI², Yusuke AKIYA³, Yuta HOZUMI³, Akinori SAITO³, Atsushi YAMAZAKI⁴ (1.Solar-Terrestrial Environment Laboratory, Nagoya University, 2.Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University, 3.Department of Geophysics, Graduate School of Science, Kyoto University, 4.Institute of Space and Astronautical Science / Japan Aerospace Exploration Agency)

Keywords:airglow, ionosphere, international space station, plasma bubble, IMAP, VISI

Under the Ionosphere, Mesosphere, upper Atmosphere, and Plasmasphere mapping (IMAP) mission, imaging observations of airglow in the upper atmosphere from International Space Station has been conducted with Visible and Infrared Spectral Imager (VISI) since October 2012. We have analyzed images of the 630.0-nm airglow obtained by the Visual and Infrared Spectral Imager. We have succeeded to detect equatorial anomaly, and plasma bubbles. In the 630-nm airglow image observed by IMAP/VISI on ISS passing over Thailand on October 28, 2012, airglow depletion elongated in the north-south direction was observed. Simultaneously, field-Aligned Irregularity (FAI) echo was observed by the EAR in Indonesia. In order to compare spatial structure of the airglow depletion and FAI, we have mapped the FAI echo region onto the northern hemisphere along the magnetic field lines. We have found that the FAI echo region coincides with the airglow depletion observed by IMAP/VISI, indicating the airglow depletion is caused by a plasma bubble. We have carried out statistical analysis of plasma bubble, and found that plasma bubblef most frequently occurs in spring and autumn equinoxes at African longitudinal sector. We have also measured zonal spacing of plasma bubbles and found that the spacing depends on longitude, suggesting that atmospheric gravity waves may seed plasma bubbles.