Characterization of Transient-Large-Amplitude Geomagnetic Perturbation Events

Abstract

Space weather events occur due to the interaction of active solar wind with near-Earth space, activating magnetohydrodynamic (MHD) and electromagnetic transfer processes that propagate throughout the magnetosphere-ionosphere (M-I) system down to the surface of Earth. Perhaps the most critical concern regarding space weather is the threat of large geomagnetically induced currents (GIC) to technological infrastructure on Earth. Flowing through man-made conductors on Earth like railways, pipelines and power grids, GICs can be large enough to cause damage to transformers resulting in major power outages and costly equipment damage (Boteler et al., 1998;Pulkkinen et al., 2017). GICs are the result of a horizontal surface electric field E induced in Earth's surface that is driven by large changes of the surface magnetic field, dB/dt, via Faraday's law of induction. Hazardous GICs associated with large, rapid magnetic disturbances often result from the most disruptive geomagnetic storms and auroral substorms. Therefore, significant efforts of the geophysical community are aimed at developing global MHD models of geomagnetic storm and substorm activity and incorporating the magnetotelluric response of the Earth to compute GICs (Pulkkinen et al., 2015;Zhang et al., 2012). However, beyond the largest space weather events, several studies suggest that there are more rapid, small-scale and localized processes involved in generating some extreme GICs (

Auroral Drivers of Large dB∕dt During Geomagnetic Storms

“…(2001) and Viljanen and Tanskanen (2011), >360 nT/min in McCuen et al. (2021), and >500 nT/min in Schillings et al. (2021).…”

“…Most of the intervals occurred in the pre‐midnight and midnight sectors. The dusk sector has the least number of events possibly because the occurrence rate of large dB/dt is lower than that in the nighttime sector (McCuen et al., 2021; Schillings et al., 2021; Viljanen & Tanskanen, 2011; Viljanen et al., 2001). Available auroral observations are also fewer because the proximity to the solar terminator means that the auroral observations are more subject to sunlight contamination than those in the nighttime sector.…”

Automated High‐Frequency Geomagnetic Disturbance Classifier: A Machine Learning Approach to Identifying Noise While Retaining High‐Frequency Components of the Geomagnetic Field

“…However, these second‐scale magnetic field changes may be especially important in understanding small‐scale dynamics of space weather events. While magnetic disturbances in this Pi 1–2 frequency range do not cause GICs directly, they have been found to occur prior to and/or during some GIC‐capable space weather events, nighttime MPEs in particular (McCuen et al., 2021).…”

“…McCuen et al. (2021) found that TLA d B /d t intervals identified in 2015 often occurred in the pre‐midnight sector (magnetic local time), 30 min after a substorm onset and in association to many of the most extreme nighttime MPEs. Of 175 MPEs at four Magnetometer Array for Cusp and Cleft Studies (MACCS) stations in 2015 (IGL, RBY, PGG, and CDR), nearly half of the 52 largest events (maximum d B /d t values greater than 10 nT/s) had associated TLA d B /d t intervals.…”

“…Figure 1 shows an example of TLA events that was published as Figure 1b of McCuen et al. (2021). The TLA events in Figure 1 occurred at five stations of the MACCS that occurred on 11 November 2015.…”