Simultaneous Observations of Geoelectric and Geomagnetic Fields Produced by Magnetospheric ULF Waves. Issue 18 (23rd September 2020)

• Record Type: Journal Article
• Authors: Hartinger, M. D.; Shi, X.; Lucas, G. M.; Murphy, B. S.; Kelbert, A.; Baker, J. B. H.; Rigler, E. J.; Bedrosian, P. A.
• Is Part Of: Geophysical research letters. Volume 47:Issue 18(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-09-23
• Subjects: ULF wave -- geoelectric field -- geomagnetic field -- virtual resonance -- geomagnetically induced current -- magnetotellurics; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL089441
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Geomagnetic perturbations ( B G E O ) related to magnetospheric ultralow frequency (ULF) waves induce electric fields within the conductive Earth—geoelectric fields ( E G E O )—that in turn drive geomagnetically induced currents. Though numerous past studies have examined ULF wave B G E O from a space weather perspective, few studies have linked ULF waves with E G E O . Using recently available magnetotelluric impedance and E G E O measurements in the contiguous United States, we explore the relationship between ULF waves and E G E O . We use satellite, ground‐based radar, B G E O, and E G E O measurements in a case study of a plasmaspheric virtual resonance (PVR), demonstrating that the PVR E G E O has significant spatial variation in contrast to a relatively uniform B G E O, consistent with spatially varying Earth conductivity. We further show ULF wave E G E O measurements during two moderate storms of ∼1 V/km. We use both results to highlight the need for more research characterizing ULF wave E G E O . Plain Language Summary: A variety of phenomena in the near‐Earth space environment produce disturbances in the magnetic field observed on the ground, including plasma waves in the ionized portion of the Earth's upper atmosphere. Though numerous studies have characterized magnetic disturbances related to waves with frequencies below a few hertz, few studies have addressed the electric fields they can induce in the Earth: geoelectric fields ( E GEO ). The latter are important because they drive potentially damaging electrical currents in power grids and other infrastructure. This study addresses the lack of constraints on wave E GEO fields by taking advantage of recently available models and measurements. The results show that extreme wave events can produce E GEO of significant amplitude, comparable to once‐per‐century values obtained in other studies. The results also indicate that more work is needed to characterize wave E GEO . Key Points: There are few measurements of ultralow frequency (ULF) wave geoelectric fields (EGEO ), despite the hazard these fields can represent A coordinated investigation of ULF waves and EGEO reveals significant spatial inhomogeneities in EGEO related to Earth conductivity Measured storm time ULF wave EGEO amplitudes of ∼300–1000 mV/km suggest that they should be considered in future geoelectric hazard analysis