Simultaneous Observations of Geoelectric and Geomagnetic Fields Produced by Magnetospheric ULF Waves

Geomagnetic perturbations (B-GEO) related to magnetospheric ultralow frequency (ULF) waves induce electric fields within the conductive Earth-geoelectric fields (E-GEO)-that in turn drive geomagnetically induced currents. Though numerous past studies have examined ULF waveB(GEO)from a space weather perspective, few studies have linked ULF waves withE(GEO). Using recently available magnetotelluric impedance andE(GEO)measurements in the contiguous United States, we explore the relationship between ULF waves andE(GEO). We use satellite, ground-based radar,B-GEO, andE(GEO)measurements in a case study of a plasmaspheric virtual resonance (PVR), demonstrating that the PVRE(GEO)has significant spatial variation in contrast to a relatively uniformB(GEO), consistent with spatially varying Earth conductivity. We further show ULF waveE(GEO)measurements during two moderate storms of similar to 1 V/km. We use both results to highlight the need for more research characterizing ULF waveE(GEO).