Trans-ionospheric signals such as the Global Positioning System (GPS) signals propagating through irregular ionospheric plasma structures may experience phase variation and amplitude fades causing degradation in system performance. This paper investigates the latitudinal structure of equatorial F-region irregularities (EFI) in the African region at different seasons using a GPS-based proxy index (rate of change of TEC index (ROTI)). The results obtained indicate the dependence of EFI on local time, season and latitude. Its occurrence time ranges between 19:00 and 0:00LT depending on the season. Its appearance is earlier in equinoxes, particularly in March equinox, and late in June solstice. Further, its occurrence lies generally within $\pm$22° magnetic latitudes for all seasons. The probability of occurrence, which is observed to be generally higher in equinoxes than solstices, is almost comparable across the entire latitudes where it was observed in equinoxes while the observations in solstices indicate a dip around the magnetic equator. Furthermore, the average seasonal value of ROTI indicates a clear latitudinal dependence; with appearance within $\pm$(0°-12°) magnetic latitude in solstices while it extends up to 18° in equinoxes, particularly in the south. While the hemispheric asymmetry in the average seasonal values is favored by the hemispheric asymmetry of latitudinal TEC profile, the TEC gradient could help delineate the latitude of its peak occurrence. In addition, severe irregularities are mostly observed in equinoxes than in solstices across all latitudes of occurrence and are most pronounced around the crest region mainly in the south. Conversely, moderate irregularities are typically observed in solstices and are most frequent around the magnetic equator and the poleward edge of equatorial ionization anomaly (EIA) region in the northern hemisphere.

跨电离层信号，例如通过不规则电离层等离子体结构传播的全球定位系统 (GPS) 信号，可能会经历相位变化和幅度衰减，从而导致系统性能下降。本文使用基于 GPS 的代理指数（TEC 指数变化率 (ROTI)）研究了非洲地区不同季节赤道 F 区不规则性 (EFI) 的纬度结构。获得的结果表明 EFI 对本地时间、季节和纬度的依赖性。它的发生时间根据季节在 19:00 到 0:00LT 之间。它在春分出现的时间更早，特别是在三月的春分和六月的夏至末。此外，它的发生通常在$\pm$所有季节的 22° 磁纬度。在春分点观测到的发生概率通常高于至点，在春分点观测到的整个纬度几乎相当，而至点观测表明磁赤道周围有倾角。此外，ROTI 的平均季节值表明明显的纬度依赖性；内有外貌$\pm$(0°-12°) 至点的磁纬度，而它在春分点延伸至 18°，特别是在南方。虽然平均季节性值中的半球不对称性受到纬度 TEC 剖面的半球不对称性的青睐，但 TEC 梯度可以帮助描绘其峰值出现的纬度。此外，在所有发生纬度的昼夜平分点上，大多数情况下都会观察到严重的不规则性，并且主要在南部的波峰地区周围最为明显。相反，中度不规则通常在至点观察到，并且最常见于磁赤道周围和北半球赤道电离异常 (EIA) 区域的极地边缘。