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

[PEM12-P07] Simultaneous and common-volume observation of Ca and Ca⁺ with a new resonance scattering lidar

*Mitsumu K. Ejiri^1,2, Masayuki Katsuragawa^3,1, Ayaka Hashimoto³, Sota Kobayashi³, Sayako Miyoshi³, Hikaru Miyagi³, Takuo T. Tsuda³, Takuji Nakamura^1,2 (1.National Institute of Polar Research, 2.The Graduate University for Advanced Studies, SOKENDAI, 3.The University of Electro-Communications)

Keywords:resonance scattering lidar observation, Calcium atom and ion, the mesosphere and lower thermosphere, neutral and ion coupling

To measure temporal variation in vertical density distributions of meteoric metal atom and ion, as a dynamical tracer in the Mesosphere and Thermosphere, and investigate the vertical mass transport, we are developing a resonance scattering lidar for simultaneous observation of Calcium atom (Ca) and ion (Ca⁺). The lidar system has an injection-locked Ti:Sapphire laser with a broad frequency tunability as a transmitter and receives the resonance scatter signals by a telescope with ~80 cm diameter. The laser oscillator is designed so that the oscillation frequencies can be tuned simultaneously to the resonance lines of Ca and Ca⁺ ion. Laser pulses of two wavelengths were emitted from a single laser resonator simultaneously, and common-volume and simultaneous measurements of Ca and Ca⁺ densities were successes in Tachikawa (36N, 139E) at 10:50-21:10 UT on December 24, 2024. Both of Ca and Ca⁺ layers were observed at 80 – 105 km during all the night. Dense-thin layers of Ca+ were seen at ~100 km before 13 UT and ~95 km around 17 UT which were slightly higher altitudes than top of Ca layer. After 16:45 UT until sunrise, Ca⁺ layer had a dense-thin layer with a few km FWHM at 90 – 95 km, while Ca did not show such a dense-thin layer. In this presentation, we will discuss dynamics and chemical process of neutral atom and ion coupling by comparison in density, height and fine structures between Ca and Ca⁺.