No abstract

In support of a multiagency project for assessing induction hazards, we present maps of extreme‐value geoelectric amplitudes over about half of the continental United States. These maps are constructed using a parameterization of induction: estimates of Earth surface impedance, obtained at discrete geographic sites from magnetotelluric survey data, are convolved with latitude‐dependent statistical maps of extreme‐value geomagnetic activity, obtained from decades of magnetic observatory data. Geoelectric amplitudes are estimated for geomagnetic waveforms having 240 s sinusoidal period and amplitudes over 10 min that exceed a once‐per‐century threshold. As a result of the combination of geographic differences in geomagnetic activity and Earth surface impedance, once‐per‐century geoelectric amplitudes span more than 2 orders of magnitude and are an intricate function of location. For north‐south induction, once‐per‐century geoelectric amplitudes across large parts of the United States have a median value of 0.26 V/km; for east‐west geomagnetic variation the median value is 0.23 V/km. At some locations, once‐per‐century geoelectric amplitudes exceed 3 V/km.

No abstract

An examination is made of opportunities and challenges for enhancing global, real‐time geomagnetic monitoring that would be beneficial for a variety of operational projects. This enhancement in geomagnetic monitoring can be attained by expanding the geographic distribution of magnetometer stations, improving the quality of magnetometer data, increasing acquisition sampling rates, increasing the promptness of data transmission, and facilitating access to and use of the data. Progress will benefit from new partnerships to leverage existing capacities and harness multisector, cross‐disciplinary, and international interests.

A review is given of the present feasibility for accurately mapping geoelectric fields across North America in near-realtime by modeling geomagnetic monitoring and magnetotelluric survey data. Should this capability be successfully developed, it could inform utility companies of magnetic-storm interference on electric-power-grid systems. That real-time mapping of geoelectric fields is a challenge is reflective of (1) the spatiotemporal complexity of geomagnetic variation, especially during magnetic storms, (2) the sparse distribution of ground-based geomagnetic monitoring stations that report data in realtime, (3) the spatial complexity of three-dimensional solid-Earth impedance, and (4) the geographically incomplete state of continental-scale magnetotelluric surveys.