The Time Derivative of the Horizontal Geomagnetic Field for the Low Latitude MAGDAS Langkawi Station for the Estimation of Geomagnetically Induced Current

Abstract

The time derivative of the horizontal magnetic field component (dH/dt) is directly related to geomagnetically induced current (GIC). From Faraday’s law of induction, the changes in geomagnetic field due to space weather perturbations can produce an electrical current to flow on the Earth’s surface and this process is the so-called GIC. Historically, many GIC activities have been reported from high latitude regions due to the very frequent and intense geomagnetic activity observed in the area. However, during strong sudden impulse (SI) events, the impact of geomagnetic disturbance may extend to low latitude regions, thus leading to GIC activity. Long-term analysis of ground magnetic changes, with dH/dt exceeding 30 nT/min at MAGDAS Langkawi station during ascending and peak Solar Cycle 24 (SC 24) was conducted in order to select the significant SI event. The analysis of the Solar Wind Speed Vx component, Interplanetary Magnetic Field, IMF Bz component and magnetic indices (AU, AE and DST) was then conducted to reveal the behavior of each of those parameters during the events. We found that during SI events in this study period, the average of the time derivative of the H-component magnetic field, dH/dt was 37.8 nT/min. Three SI events were analyzed and was observed that the characteristics of solar wind speed and interplanetary magnetic field during the storm can influence the strength of the local geomagnetic disturbance. Furthermore, the signature of magnetic disturbance process and amplitude of dH/dt at this station also depended strongly on which side of the Earth’s was facing the SI event. The findings of the study show that an SI event during noon side with IMF Bz component points southward induce stronger ground magnetic disturbance and a larger amplitude of dH/dt even though a smaller increase of solar wind speed Vx is recorded compared to any SI events that occurred on night side with northward pointing of IMF Bz. In overall, the analysis on dH/dt of this study shows the possibility of GIC occurrence in Malaysia and further investigation and experimentation on GIC activity is strongly recommended.