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Geomagnetism publications.

Filter Total Items: 415

The solar cycle, geology, and geoelectric hazards for power grids

When sunspots are large and numerous, intense magnetic storms are likely to occur on the Earth. Magnetic storms can generate electric fields in the Earth, and these fields can, in turn, interfere with electric power transmission grids that are grounded at the Earth’s surface. Across the contiguous United States, geoelectric hazards are highest in the Upper Midwest and in the East. These regions co
Authors
Jeffrey J. Love, Steven Sobieszczyk, E. Joshua Rigler, Anna Kelbert, Kristen A. Lewis

Challenging ring-current models of the Carrington storm

A detailed analysis is made of horizontal-component geomagnetic-disturbance data acquired at the Colaba observatory in India recording the Carrington magnetic storm of September 1859. Prior to attaining its maximum absolute value, disturbance at Colaba increased with an e-folding timescale of 0.46 hr (28 min). Following its maximum, absolute disturbance at Colaba decreased as a trend having an e-f
Authors
Jeffrey J. Love, Kalevi Mursula

On the uncertain intensity estimate of the 1859 Carrington storm

A study is made of the intensity of the Carrington magnetic storm of September 1859 as inferred from visual measurements of horizontal-component geomagnetic disturbance made at the Colaba observatory in India. Using data from modern observatories, a lognormal statistical model of storm intensity is developed, to characterize the maximum-negative value of the storm-time disturbance index (maximum –
Authors
Jeffrey J. Love, E. Joshua Rigler, H. Hayakawa, Kalevi Mursula

Hybrid CPU-GPU solution to regularized divergence-free curl-curl equations for electromagnetic inversion problems

The Curl-Curl equation is the foundation of time-harmonic electromagnetic (EM) problems in geophysics. The efficiency of its solution is key to EM simulations, accounting for over 95% of the computation cost in geophysical inversions for magnetotelluric or controlled-source EM problems. However, most published EM inversion codes are still central processing unit (CPU)-based and cannot utilize rece
Authors
Hao Dong, Kai Sun, Gary D. Egbert, Anna Kelbert, Naser Meqbel

Geoelectric field model validation in the southern California Edison system: Case study

Geomagnetic storms are a natural phenomenon that cause magnetic field variations at the surface of the Earth. These variations induce electrical current in natural and artificial conductors at and below the surface, resulting in geomagnetically induced currents (GIC) in power systems. The key to modeling GIC is to estimate the geoelectric field in the region of the power grid. The estimation of GI
Authors
Christopher C. Balch, Chaoyang Jing, Anna Kelbert, Patricia Arons, Kevin Richardson

The March 1940 superstorm: Geoelectromagnetic hazards and impacts on American communication and power systems

An analysis is made of geophysical records of the 24 March 1940, magnetic storm and related reports of interference on long-line communication and power systems across the contiguous United States and, to a lesser extent, Canada. Most long-line system interference occurred during local daytime, after the second of two storm sudden commencements and during the early part of the storm's main phase.
Authors
Jeffrey J. Love, E. Joshua Rigler, Michael D Hartinger, Greg M. Lucas, Anna Kelbert, Paul A. Bedrosian

Modeling geomagnetic induction in submarine cables

Submarine cables have become a vital component of modern infrastructure, but past submarine cable natural hazard studies have mostly focused on potential cable damage from landslides and tsunamis. A handful of studies examine the possibility of space weather effects in submarine cables. The main purpose of this study is to develop a computational model, using Python, of geomagnetic induction on su
Authors
Shibaji Chakraborty, David H. Boteler, Xueling Shi, Benjamin Scott Murphy, Michael D. Hartinger, Xuan Wang, Greg M. Lucas, Joseph B. H. Baker

Synthesizing ground magnetic disturbance using dipole-aligned loop elementary currents and Biot-Savart relationship

This report presents a method for constructing a simplified numerical description of the electric current distributions in the ionosphere and gap region based on dipole-aligned loop elementary currents (DALECs). A theoretical basis for DALECs is presented, along with a prototypical algorithm for constructing an elementary numerical DALEC. The algorithm is verified and validated by combining DALECs
Authors
E. Joshua Rigler, Michael Wiltberger

Magnetotelluric sampling and geoelectric hazard estimation: Are national-scale surveys sufficient?

At present, the most reliable information for inferring storm-time ground electric fields along electrical transmission lines comes from coarsely sampled, national-scale magnetotelluric (MT) data sets, such as that provided by the EarthScope USArray program. An underlying assumption in the use of such data is that they adequately sample the spatial heterogeneity of the surface relationship between
Authors
Benjamin Scott Murphy, Greg M. Lucas, Jeffrey J. Love, Anna Kelbert, Paul A. Bedrosian, E. Joshua Rigler

Geomagnetic monitoring in the mid-Atlantic United States

Near historic battlegrounds of the American Civil War, southeast of Fredericksburg, Virginia, on a secluded grassy glade surrounded by forest, a specially designed observatory records the Earth’s changing magnetic field. This facility, the Fredericksburg Magnetic Observatory, is 1 of 14 observatories the U.S. Geological Survey Geomagnetism Program operates at various locations across the United St
Authors
Jeffrey J. Love, Kristen A. Lewis

Electrical conductivity of the lithosphere-asthenosphere system

Electromagnetic geophysical methods image the electrical conductivity of the subsurface. Electrical conductivity is an intrinsic material property that is sensitive to temperature, composition, porosity, volatile and/or melt content, and other physical properties relevant to the solid Earth. Therefore, imaging the electrical structure of the crust and mantle yields valuable information on the phys
Authors
Samer Naif, Kate Selway, Benjamin Scott Murphy, Gary D. Egbert, Anne Pommier

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

Geomagnetic perturbations (BGEO) related to magnetospheric ultralow frequency (ULF) waves induce electric fields within the conductive Earth—geoelectric fields (EGEO)—that in turn drive geomagnetically induced currents. Though numerous past studies have examined ULF wave BGEO from a space weather perspective, few studies have linked ULF waves with EGEO. Using recently available magnetotelluric imp
Authors
M. D. Hartinger, X. R. Shih, G. Lucas, Benjamin Scott Murphy, Anna Kelbert, J.B.H. Baker, E. Joshua Rigler, Paul A. Bedrosian
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