[P-EM11] Coupling Processes in the Atmosphere-Ionosphere System

[PEM11-P22] Relationship between energetic particle precipitations and an intensity of OH airglow over Syowa Station.

*Satoshi Ishii¹, Hidehiko Suzuki¹, Masaki Tsutsumi^2,4, Makoto Taguchi³, Mitsumu K. Ejiri^2,4, Takanori Nishiyama^2,4 (1.Meiji University, 2.National Institute of Polar Research, 3.Rikkyo University, 4.SOKENDAI)

Keywords:OH airglow, Aurora, Mesopause, Lower thermosphere

OH airglow is luminous phenomena in upper mesosphere which has a thin layer with a peak altitude of ~ 85 km. Origin of OH airglow is an emission from Meinel vibration-rotation band of OH molecule excited by an exothermic reaction between ozone molecule and atomic hydrogen. Rotational temperature, which is believe to be equivalent with neutral temperature of background atmosphere in the mesosphere, can be estimated by observing intensity ratio among rotational lines in the band spectrum. Intensity of OH airglow highly depends on dynamics and photochemical reactions involving minor species in upper mesosphere region. Thus, remote sensing of OH airglow is an effective method to monitor the upper mesosphere and widely carried out by many observers. We have conducted OH airglow observation in Syowa Station, Antarctic during winter season (From an end of Feb to middle of Oct) of 2008-2019 by using an OH spectrometer. The OH spectrometer can measure the OH spectrum even under the moderate aurora condition since it is designed to suppress the contamination from aurora emissions. In this study, we show variations of the intensity of OH airglow which are likely related with auroral activity over Syowa Station. We focused on a sudden enhancement of intensity of OH airglow with a time scale from several ten minutes to several days. Such events do not show sinusoidal oscillations which are frequently caused by atmospheric gravity waves. These events are considered to be a result of an enhancement of vertical transport of [O]-rich air to the airglow layers. We discuss the effect on the OH intensity caused by combination of auroral precipitation which modulates a vertical profile of [O] and dynamical effects which enhance a vertical transportation of [O].