Simultaneous observations of geoelectric and geomagnetic fields produced by magnetospheric ULF waves

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 .