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

[PEM11-19] Ionospheric Quai-6-Day Oscillation generated by the Secondary Waves During the 2019 Antarctic Sudden Stratosphere Warming

*Jia-Ting Lin¹, Charles Lin¹, Loren Chang^2,3, Nicholas M Pedatella^4,5, P. K. Rajesh¹, CHIYEN LIN^2,3 (1.Department of Earth Science, National Cheng Kung University, Tainan, Taiwan, 2.Department of Space Science & Engineering, National Central University, Taoyuan, Taiwan, 3.Center for Astronautical Physics and Engineering, National Central University, Taoyuan, Taiwan, 4.High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO, USA, 5.COSMIC Program Office, University Corporation for Atmospheric Research, Boulder, CO, USA)

Keywords:Sudden Stratospheric Warming, Ionospheric Variabilities, Quasi-6-day Wave, Secondary Waves, Vertical Coupling

During the rare Antarctic sudden stratospheric warming (SSW) in September 2019, the quasi-6-day wave (Q6DW) was dramatically enhanced in the mesosphere and lower thermosphere (MLT) region, and strong quasi-6-day oscillations (Q6DO) are observed in ionospheric equatorial electrojet and electron density. However, model simulations demonstrated that the Q6DO in the ionosphere is not driven directly by the Q6DW during the September 2019 SSW. Instead of the secondary waves generated by nonlinear interaction between the Q6DW and semi-diurnal migrating tide. In this study, we examine the amplitude variations of Q6DO and shorter period child waves by using data-assimilation analysis of electron density from three-dimensional Global Ionosphere Specification (GIS). We focus on the behaviors of W1_13h and W3_11h, which are the largest in the secondary waves and are the possible contributors to the ionospheric Q6DO. The day-to-day variabilities of child waves show that both the W1_13h and W3_11h are dramatically enhanced after the SSW peak, growing in amplitude at the EIA region with poleward extension from negligible amplitude. The amplitudes reach maximum and contribute about 6 % to the zonal and diurnal mean background, which coincides with the day of maximum amplitude of Q6DO. The amplitude distributions of two child waves are also overlapped with comparable amplitude. These results suggest that the two child waves might interfere with each other at the EIA regions, resulting in the change of the amplitudes and phases of Q6DO at the different local times if their contributions are not uniform in local time. Additionally, child waves activity during the same period in the non-SSW year of 2020 is also examined for comparison.