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

[PEM12-P22] Investigation on seasonal variation in potassium layer over Syowa station (69.0°S, 39.6°E), Antarctic

*Jinyi Hu¹, Takuo T. Tsuda¹, Ryoga Kitai¹, Mitsumu K. Ejiri^2,3, Takanori Nishiyama^2,3, Takuji Nakamura^2,3, Katsuhiko Tsuno⁴, Makoto Abo⁵, Takuya D. Kawahara⁶, Takayo Ogawa⁴, Satoshi Wada⁴ (1.University of Electro-Communications, 2.National Institute of Polar Research, 3.SOKENDAI, 4.RIKEN, 5.Tokyo Metropolitan University, 6.Shinshu University)

Keywords:K layer, Resonance scattering lidar, Syowa

Metallic layers, containing such as Na, Fe, K, etc., originating from meteors are valuable tracers for performing observations of the Earth's upper atmosphere. Through investigations on variations in such metallic layers, it would be important to advance our understanding on the atmospheric dynamical and chemical processes in the region where it is not easy to make observations. As for Na and Fe, many observations have been done for decades, and their variations have been widely investigated. On the other hand, observational data on K are relatively limited. In previous K observations, there are several reports from resonance scattering lidars located in the Northern Hemisphere, and from a shipboard-lidar campaign between 71°S and 45°N. In addition, there are investigations based on near-global K data, which were obtained by observations of resonance scattering of sunlight from a satellite. On the other hand, there are fewer K observations in winter high latitudes in the Southern Hemisphere, where there is less sunlight.

In the present work, we have investigated seasonal variation in K layer over Syowa station (69.0°S, 39.6° E), Antarctic, based on observational data which were obtained by a resonance scattering lidar. The resonance scattering lidar was installed at Syowa station in 2017, and it was operated from 2017 to 2018. During the period, K density data of 381 hours were obtained from K D₁ (770 nm) observations of 38 days mainly during the Antarctic winter. These data were analyzed to investigate seasonal variation in K layer over Syowa station. As a result, the peak heights of K number density were mostly 85 to 90 km. The K peak density reached a maximum in June-July during wintertime, and its number density was approximately 2×10⁷ m^-3. Then, a minimum of the K peak density was observed in September during springtime, and its number density was approximately 2×10⁶ m^-3. In the presentation, we will show these results, together with comparisons to the previous K observations, and discuss the importance of K chemical process for the observed seasonal variation in K layer over Syowa station.