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

[PEM11-P13] The relation between hmF2 and radio occultation scintillation amplitude index RO-S4 index observed using FORMOSAT-7/COSMIC-2

*YI DUANN^1,2, Loren Chang^1,2, Chi-Kuang Chao^1,2, Jann-Yenq Liu^1,2, Tung-Yuan Hsiao³, Shih-Ping Chen⁴ (1.Department of Space Science and Engineering, National Central University, Taoyuan City, Taiwan, 2.Center for Astronautical Physics and Engineering, National Central University, Taoyuan City, Taiwan, 3.Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu City, Taiwan, 4.Department of Earth Sciences, National Cheng Kung University, Tainan City, Taiwan)

Keywords:S4 index, hmF2, Equatorial plasma bubbles (EPBs), FORMOSAT-7/COSMIC-2 (F7/C2)

Six FORMOSAT-7/COSMIC-2 (F7/C2) satellites were launched into 24 degrees inclination low Earth orbit on June 25^th 2019, The data from the primary Tri-GNSS Radio occultation System (TGRS) space weather products: relative total electron content (TEC), scintillation amplitude index (S4), and electron density (Ne) profile have been released. This study focuses on the comparison of F7/C2 radio occultation scintillation amplitude (RO-S4) index and Ne profiles acquired within a time difference of 30 minutes and spatial difference of 110 km (1 degree of longitude and latitude). These nearly collocated observations are examined to clarify, the relation between S4 index and the height of peak electron density in F2 layer (hmF2), and how S4 index and hmF2 play roles in the occurrences and growth rate of equatorial plasma bubbles (EPBs) due to plasma uplift. The S4 observations at low latitudes derived from the F7/C2 radio occultation experiment are compared with range-time-intensity (RTI) maps of the 50 MHz radar near Jicamarca and the Global scale Observations of the Limb and Disk (GOLD) mission observed 135.6 nm airglow depletions by Chen et al. (2020), and the results show that RO-S4 intensities can be utilized to identify EPBs of specific scales. On the other hand, the longitudinal and seasonal distributions of the hmF2 observed by FORMOSAT-3/COSMIC during the growth phase of EPBs from 2008 to 2013 by Chou et al. (2020) indicates that the casual relationship of EPBs and the hmF2 should be examined in more detail. Ghosh et al. (2020) presents that the hmF2 elevated to higher altitudes by prereversal enhancement (PRE) around evening terminator due to eastward electric field at the magnetic equator, while Ne in the F region shows negative correlation with peak PREs that could be driven by fountain effect. The comparison of different local time periods and locations is analyzed and discussed in this study as well, in order to improve our understanding of the relation between ionospheric structure and the generation mechanism of plasma irregularities.