Characteristics and Sources of Intense Geoelectric Fields in the United States during Geomagnetic Storms

When (times in MT)
Wed, Jul 20 2022, 2pm - 1 hour
Event Type
Xueling Shi
Virginia Tech

Intense geoelectric fields during geomagnetic storms drive geomagnetically induced currents (GIC) in power grids and other infrastructure, yet there are limited direct measurements of these storm-time geoelectric fields. Moreover, most previous studies examining storm-time geoelectric fields focused on single events or small geographic regions, making it difficult to determine the typical source(s) of intense geoelectric fields. We report a comparative analysis of the characteristics and sources of intense geoelectric fields over multiple geomagnetic storms, using 1-s cadence geoelectric field measurements made at magnetotelluric (MT) survey sites distributed widely across the United States. Temporally localized intense perturbations in measured geoelectric fields with prominences of at least 500 mV/km were detected during geomagnetic storms with Dst minima (Dstmin) of less than −100 nT from 2006 to 2019. Various sources of intense geoelectric fields have been identified, including interplanetary shocks, interplanetary magnetic field turnings, substorms, and ultralow frequency (ULF) waves. Detailed case studies showing different driving mechanisms of intense geoelectric fields were also investigated using coordinated space and ground observations. The sources of intense geoelectric fields differ from storm to storm. This is likely because the generation of geoelectric fields depends on multiple factors including regional Earth conductivity, sources from the solar wind and magnetosphere-ionosphere system, as well as the location of observations relative to these sources. 

About the Speaker

Dr. Xueling Shi is a Research Scientist from Virginia Tech and also a scientific visitor at HAO since 2019. Dr. Shi started her PhD at Virginia Tech in 2014 and defended her dissertation in 2019, during which she worked with Professors J. Michael Ruohoniemi and Joseph Baker in the SuperDARN research group on ultra-low frequency (ULF) waves and their space weather impacts. Before that, she obtained her Master’s degree in Space Physics from University of Chinese Academy of Sciences in 2014 and her Bachelor’s degree from Wuhan University in 2011.