The east–west component of magnetic field variation (∆D-component) at Davao station (Philippines, geomagnetic latitude: – 2.22˚N) are used to investigate the characteristics of the long-term Inter-Hemispheric Field-Aligned Currents (IHFACs) based on the time-series analysis from August 1998 to July 2020. Recent in situ satellite and ground-based observations have reported that dusk-side current polarity of IHFAC is often opposite to that of the noon IHFAC, being inconsistent with Fukushima's IHFACs model. We investigated the consistency of the dusk-side IHFAC polarity derived from the observations with the polarity expected from Fukushima’s IHFACs model and examined the solar cycle dependence of IHFACs. It was confirmed that the dusk-side IHFACs during June and December solstices flow in the same direction of the noontime IHFACs, which was consistent with the IHFAC polarities suggested by the Fukushima model. The dusk-side IHFACs around March and September–November months disagreed with the Fukushima model. The ∆D variations clearly showed seasonal asymmetry in the dawn and noon sectors, whereas the ∆D variations in the dusk sector demonstrated seasonal symmetry. Solar cycle dependence of IHFACs was exhibited in the dusk sector. For the dawn and noon sectors, the yearly peak-to-peak ∆D amplitude in the later solar cycle SC24 decreased by about 35% in comparison with the earlier solar cycle SC23. In contrast, the dusk-side yearly peak-to-peak ∆D amplitude increased by about 200%. The dusk-side IHFAC yearly amplitude tended to be in inverse proportion to solar activity.

磁场变化的东西向分量 (Δ D-分量）在达沃站（菲律宾，地磁纬度：– 2.22˚N）用于研究基于 1998 年 8 月至 7 月的时间序列分析的长期半球间场对齐流 (IHFAC) 的特征2020. 最近的卫星和地面观测表明，IHFAC 的黄昏侧电流极性往往与中午 IHFAC 的极性相反，与福岛的 IHFACs 模型不一致。我们研究了观测得出的黄昏侧 IHFAC 极性与福岛 IHFAC 模型预期的极性的一致性，并检查了 IHFAC 的太阳周期依赖性。已确认 6 月和 12 月至日的黄昏侧 IHFAC 与中午 IHFAC 的流动方向相同，这与福岛模型建议的 IHFAC 极性一致。3 月和 9 月至 11 月左右的黄昏 IHFAC 不同意福岛模型。∆黎明和中午扇区的D变化清楚地显示出季节性不对称，而黄昏扇区的 Δ D变化则显示出季节性对称性。IHFACs 的太阳周期依赖性表现在黄昏区域。对于黎明和中午扇区，与较早的太阳周期 SC23 相比，后期太阳周期 SC24的年峰峰值 ∆ D幅度下降了约 35%。相比之下，黄昏侧的年峰峰值∆D幅度增​​加了约 200%。黄昏侧的 IHFAC 年振幅往往与太阳活动成反比。