This investigation presents for the first time the seasonal and solar cycle variations of the daytime F-layer multiple stratifications (F3 and F4 layers) near the southern crest of the EIA in two different longitudinal sectors of South America. To perform the study, the ionograms recorded from 2007 to 2015 at Sao José dos Campos (23.2°S, 45.9°W), Brazil (eastern sector), and at Tucumán (26.9°S, 65.4°W), Argentina (western sector), are considered. Both sites present a frequency of occurrence of the F3 and F4 layers which is directly proportional to the solar activity, and an annual variation with a maximum in spring/summer and a minimum in autumn/winter. The main result that came out from the analysis is that the frequency of occurrence of the F3 and F4 layers is higher in the western sector than in the eastern sector, and this could be attributed to a different gravity waves activity characterizing the two longitudinal sectors.

这项调查首次展示了南美洲两个不同纵向扇区中 EIA 南峰附近白天 F 层多层（F3 和 F4 层）的季节性和太阳周期变化。为了进行这项研究，2007 年至 2015 年在巴西（东区）的圣何塞杜斯坎波斯（23.2°S，45.9°W）和阿根廷（西区）的 Tucumán（26.9°S，65.4°W）记录的电离图）， 被考虑。两个站点都呈现出与太阳活动成正比的 F3 和 F4 层的出现频率，以及春/夏最大和秋/冬最小的年度变化。分析得出的主要结果是西段F3和F4层的出现频率高于东段，