Effect of the seed perturbation amplitude on the equatorial spread F initiation during solar minimum

• Published in: Advances in space research Vol. 71; no. 1; pp. 255 - 267
• Main Authors: Afolayan, AO, Mandeep, JS, Abdullah, M, S A Hamid, N, Yokoyama, T
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2023
• Subjects: Density scale-length; Equatorial Spread F; Gravity wave; Plasma drift; R-T instability; Equatorial Spread F; Plasma drift; Gravity wave; R-T instability; Density scale-length
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2022.09.035

•Role of the GW amplitude in the observed ESF onset during the period with weak ambient ionospheric condition.•Comparison of the GW influence on the ESF onset during March and October of the LSA period.•Experimental observation of the GW and density scale length effect on the plasma irregularity evolution process. The contribution of gravity wave (GW) to the initiation/development of spread F during a solar minimum year was investigated through the comparison of the observed precursory parameters and characteristics of the corresponding equatorial spread F (ESF) events. The ionospheric parameters were recorded at the magnetic equatorial station Sao Luis (2.3°S, 44°W, dip latitude 2°S) during March and October 2010. These data were used to estimate the influence of the relative gravity wave amplitude and the ambient ionospheric condition on the diurnal variation of the spread F initiation. The vertical velocity drift indicated a clear control and defines the threshold for the seasonal variability of the ESF occurrence. However, it was insufficient to solely determine or predict the day to day variation of ESF occurrence. Thus, few days with contrasting ambient ionospheric condition and magnitude of GW amplitude were analysed in order to investigate the role of the different precursory factors in the observed diurnal variation of the plasma irregularity development. The density scale length and gravity wave amplitude were shown to immensely contribute to the linear instability growth rate, especially during the days with a low post-sunset rise. Thus, the experimental observations have demonstrated the strong inter-dependence between the precursory factors and they have also highlighted the probable control of the ESF morphology.