Short and Long‐Term Variations in Geomagnetic External Field: Study Based on 104 Years of Geomagnetic Observations From the Indian Low Latitude Station‐Alibag

This study examines the variations of all three components of the geomagnetic field over a low‐latitude Indian station Alibag (18°N, 72°E) during the past 104 years (1921–2024). The quiet time diurnal variations in the northward (Δ X ) component represent the solar quiet (Sq) current, while the Δ Y component represents combined signatures of Sq and Inter–hemispheric Field‐Aligned Currents (IHFAC), and the vertical (Δ Z ) component is a combination of Sq and induced currents. The response of these components to solar activity in different seasons has been investigated and found to be highest during the summer months and lowest during winter. The amplitudes of Δ X components are consistently higher in spring than in autumn, which is opposite for Δ Y and Δ Z . Further, the reversal in the polarity of Δ Y with local time and seasons confirms the contribution of IHFAC, and hence the responses of IHFAC to solar cycle have been examined. Additionally, geomagnetic main field (core origin field) variations have also been extracted from quiet day midnight data to examine the secular variations. Further, the long‐term variations in the Sq and residual Sq have also been analyzed, both show decreasing trend.