Characterization of Transient Induced Current Events Observed in Ground Magnetometer Data

Abstract:

Transient induced currents (TIC) are caused by rapid, large-amplitude magnetic disturbances with shorter timescale (< 1 minute) than typical geomagnetically induced currents. We present a characterization of transient induced current events that occurred at six stations of the Magnetometer Array for Cusp and Cleft Studies throughout 2015. Transient induced current events are defined as one or more short-timescale |dB/dt| signature with magnitude exceeding 6 nT/s and duration < 1 minute throughout 2015. We characterize these events based on frequency of occurrence, temporal dependence, and relation to other geomagnetic events. We identified 56 transient induced current events from all six stations with duration less than 1 minute, and we demonstrate the existence of large amplitude magnetic perturbations with timescale less than 10 seconds in 14 of the events found. We also surveyed magnetic disturbances with the same magnitude but with duration extending to five minutes and found no such events with timescale 2-5 minutes. The relation to sudden commencements is weaker than expected, rather the events are more strongly associated with substorm activity. Our findings suggest that the transient induced currents associated with these short-timescale geomagnetic impulses have different properties than typical geomagnetically induced currents. The potential space weather impacts of transient induced current events is discussed as these currents may be hazardous to conductive components of the rapidly growing Internet of Things network.