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Abstract <p>Geomagnetic storms (GSs), driven by solar activity, produce significant disturbances in the Earth’s magnetic field—particularly in its horizontal component (H). This study investigates the response of the <i>H</i>-component to GSs during solar cycle 24 (2009–2019), using ground-based magnetometer data recorded at the TAM observatory in Tamanrasset, Algeria (22.79° N, 5.53° E), part of the INTERMAGNET network. A total of 130 storms were identified based on <i>Dst-</i>index thresholds and classified into 104 moderate (–100 nT &lt; <i>Dst</i> ≤ –50 nT) and 26 intense (<i>Dst</i> ≤ –100 nT) events. The <i>H</i>-component was derived from the orthogonal north and east components (<i>X</i>, <i>Y</i>) of the geomagnetic field. The results reveal a gradual upward trend in the <i>H</i>-component over the solar cycle, consistent with secular geomagnetic field variations. However, during storm periods, the <i>H</i>-component exhibited significant decreases. These disturbances were quantified using the maximum deviation parameter Δ<i>H</i><sub>max</sub>, which displayed a statistically significant positive correlation with storm intensity (<i>r</i> = 0.71). Notably, the correlation was stronger for intense storms (<i>r</i>&#xa0;= 0.75) than moderate ones (<i>r</i> = 0.38). These results highlight the greater sensitivity of low-latitude geomagnetic observatories to high-intensity storms and demonstrate the diagnostic value of Δ<i>H</i><sub>max</sub> for space weather monitoring.</p>

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H-Component Variations Induced by Geomagnetic Storms during Solar Cycle 24: Insights from TAM Observatory

  • 期刊论文

  • 发表日期：

    2025年8月9日

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  • Y. Bouderba,
  • A. Benali,
  • K. Benghanem,
  • A. Lemgharbi,
  • E. Aganou,
  • M. E. Honore

摘要

Abstract

Geomagnetic storms (GSs), driven by solar activity, produce significant disturbances in the Earth’s magnetic field—particularly in its horizontal component (H). This study investigates the response of the H-component to GSs during solar cycle 24 (2009–2019), using ground-based magnetometer data recorded at the TAM observatory in Tamanrasset, Algeria (22.79° N, 5.53° E), part of the INTERMAGNET network. A total of 130 storms were identified based on Dst-index thresholds and classified into 104 moderate (–100 nT < Dst ≤ –50 nT) and 26 intense (Dst ≤ –100 nT) events. The H-component was derived from the orthogonal north and east components (X, Y) of the geomagnetic field. The results reveal a gradual upward trend in the H-component over the solar cycle, consistent with secular geomagnetic field variations. However, during storm periods, the H-component exhibited significant decreases. These disturbances were quantified using the maximum deviation parameter ΔHmax, which displayed a statistically significant positive correlation with storm intensity (r = 0.71). Notably, the correlation was stronger for intense storms (r = 0.75) than moderate ones (r = 0.38). These results highlight the greater sensitivity of low-latitude geomagnetic observatories to high-intensity storms and demonstrate the diagnostic value of ΔHmax for space weather monitoring.