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

[PEM12-P07] Study of the Relationship between OH Airglow Intensity and Aurora Particles in the Polar Mesopause Region

*Satoshi Ishii¹, Hidehiko Suzuki², Yoshimasa Tanaka^3,4,5, Masaki Tsutsumi^4,5, Makoto Taguchi¹, Mitsumu K. Ejiri^4,5, Takanori Nishiyama^4,5, Akira Kadokura^3,4,5 (1.Rikkyo University, 2.Meiji University, 3.ROIS-DS, 4.NIPR, 5.SOKENDAI)

Keywords:Polar mesopause, OH airglow, Aurora, Ground-based spectral observation

We conducted spectral observations of OH (8-4) airglow emitting at an altitude of about 86 km, at Syowa Station during the winter season from February 2008 to October 2019. These observations have continued since 2021. From these observations, we derived rotational line intensities of OH airglow (OH intensity) and rotational temperatures. We detected distinct intensity variations occurring within several tens of minutes to several hours. These variations differed from the sinusoidal patterns caused by atmospheric gravity waves, commonly seen in the mid-latitude regions. Instead, they exhibited a sharp peak. The OH molecule becomes excited through an exothermic reaction between an ozone molecule and an atomic hydrogen. It is believed that energetic particle precipitation (EPP) into the upper atmosphere produces NOx and HOx, which subsequently leads to destruction of ozone molecules. Therefore, the intensity of the OH airglow is believed to fluctuate due to changes in the atmospheric composition in the upper polar mesosphere associated with EPP. We extracted EPP events from cosmic radio noise absorption data obtained from the imaging riometer observations at Syowa Station. Image data taken by the color digital cameras at Syowa Station were used to check auroral activities. Analysis using these data suggests that some events of the OH intensity variations occurring within a few hours appear to be correlated with the temporal development of auroral substorms. The OH intensity increases and decreases before and after the EPP events, respectively, and decreases when the aurora becomes active.
In this presentation, we will illustrate the temporal variations in the OH intensity correlated with the auroral activities detected over Syowa Station from 2016 to 2022. Additionally, we will discuss the effects of precipitating auroral particles in the polar mesopause regions.