Oral Presentation
Statistical characteristics of 3-m field-aligned irregularities of sporadic E layer during the summer 2017 and 2018
Presenter: Ting-Han Lin (Graduate Institute of Space Science and Engineering, National Central University)
Radar echoes from 3-m field-aligned plasma irregularities (FAIs) of ionospheric sporadic E (Es) layer are analyzed and investigated in this study by using the Chungli VHF radar. Based on four months of data during the summer 2017 and 2018, the interferometry result shows that the statistical characteristics of total power, spectral width, Doppler shift, height and Doppler velocity shear of FAIs structure have temporal and spatial variations in Es region. According to the daily variation of Doppler shift, total power and spectral width of FAIs, it is possible to speculate that the polarization electric field during nighttime and daytime is different. Moreover, the occurrence rate of FAIs shows a two-peaks distribution in height, based on the comparison between the daily variation of height of FAIs and the simulation result via Horizontal Wind Model (HWM14), the two-peaks distribution might be attributed to the combination of the neutral wind modulation and the lower occurrence of FAIs in daytime. Furthermore, there is a significant positive correlation between Doppler velocity shear and spectral width of FAIs, it might imply that the generation of FAIs could be attributed to Kelvin–Helmholtz instability rather than the two-step instability theory.
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