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Geomagnetism publications.

Filter Total Items: 411

Geoelectric monitoring at the Boulder magnetic observatory

Despite its importance to a range of applied and fundamental studies, and obvious parallels to a robust network of magnetic-field observatories, long-term geoelectric field monitoring is rarely performed. The installation of a new geoelectric monitoring system at the Boulder magnetic observatory of the US Geological Survey is summarized. Data from the system are expected, among other things, to be
Authors
Cletus Blum, Tim White, Edward A. Sauter, Duff Stewart, Paul A. Bedrosian, Jeffrey J. Love

Some results from ModEM3DMT, the freely available OSU 3D MT inversion code

At the 3DEM-5 workshop in 2013, we presented a paper entitled "ModEM: developing 3D EM inversion for the masses", outlining our then recent development of a modular system for inversion of EM geophysical data, called ModEM. As promised in that presentation, we made a version of the code that is suitable for 3D modeling and inversion of magnetotelluric data freely available for academic use shortly
Authors
Gary D. Egbert, Naser Meqbel, Anna Kelbert

U.S. Geological Survey experience with the residual absolutes method

The U.S. Geological Survey (USGS) Geomagnetism Program has developed and tested the residual method of absolutes, with the assistance of the Danish Technical University's (DTU) Geomagnetism Program. Three years of testing were performed at College Magnetic Observatory (CMO), Fairbanks, Alaska, to compare the residual method with the null method. Results show that the two methods compare very well
Authors
E. William Worthington, Jurgen Matzka

Methodology for time-domain estimation of storm time geoelectric fields using the 3-D magnetotelluric response tensors

Geoelectric fields at the Earth's surface caused by magnetic storms constitute a hazard to the operation of electric power grids and related infrastructure. The ability to estimate these geoelectric fields in close to real time and provide local predictions would better equip the industry to mitigate negative impacts on their operations. Here we report progress toward this goal: development of rob
Authors
Anna Kelbert, Christopher Balch, Antti Pulkkinen, Gary D. Egbert, Jeffrey J. Love, E. Joshua Rigler, Ikuko Fujii

Geomagnetically induced currents: Science, engineering, and applications readiness

This paper is the primary deliverable of the very first NASA Living With a Star Institute Working Group, Geomagnetically Induced Currents (GIC) Working Group. The paper provides a broad overview of the current status and future challenges pertaining to the science, engineering, and applications of the GIC problem. Science is understood here as the basic space and Earth sciences research that allow
Authors
Antti Pulkkinen, E. Bernabeu, A. Thomson, A. Viljanen, R. Pirjola, D. Boteler, J. Eichner, P.J. Cilliers, D. Welling, N.P. Savani, R.S. Weigel, Jeffrey J. Love, Christopher Balch, C.M. Ngwira, G. Crowley, Adam Schultz, R. Kataoka, B. Anderson, D. Fugate, J.J. Simpson, M. MacAlester

Real-time geomagnetic monitoring for space weather-related applications: Opportunities and challenges

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 pr
Authors
Jeffrey J. Love, Carol Finn

Magnetic monitoring in Saguaro National Park

On a sandy, arid plain, near the Rincon Moun­tain Visitor Center of Saguaro National Park, tucked in among brittlebush, creosote, and other hardy desert plants, is an unusual type of observatory—a small unmanned station that is used for monitor­ing the Earth’s variable magnetic field. Named for the nearby city of Tucson, Arizona, the observatory is 1 of 14 that the Geomagnetism Program of the U.S.
Authors
Jeffrey J. Love, Carol Finn, Yesenia C. Gamez Valdez, Don Swann

Down to Earth with an electric hazard from space

In reaching across traditional disciplinary boundaries, solid-Earth geophysicists and space physicists are forging new collaborations to map magnetic-storm hazards for electric-power grids. Future progress in evaluation storm time geoelectric hazards will come primarily through monitoring, surveys, and modeling of related data.
Authors
Jeffrey J. Love, Paul A. Bedrosian, Adam Schultz

Time-causal decomposition of geomagnetic time series into secular variation, solar quiet, and disturbance signals

A theoretical basis and prototype numerical algorithm are provided that decompose regular time series of geomagnetic observations into three components: secular variation; solar quiet, and disturbance. Respectively, these three components correspond roughly to slow changes in the Earth’s internal magnetic field, periodic daily variations caused by quasi-stationary (with respect to the sun) electri
Authors
E. Joshua Rigler

Paleomagnetism and 40Ar/39Ar geochronology of the Plio-Pleistocene Boring Volcanic Field: Implications for the geomagnetic polarity time scale and paleosecular variation

Paleomagnetic directions and 40Ar/39Ar ages have been determined for samples of lava flows from the same outcrops, where possible, for 84 eruptive units ranging in age from 3200 ka to 60 ka within the Boring Volcanic Field (BVF) of the Pacific Northwest, USA. This study expands upon our previous results for the BVF, and compares the combined results with the current geomagnetic polarity time scale
Authors
Jonathan T. Hagstrum, Robert J. Fleck, Russell C. Evarts, Andrew T. Calvert

Extreme geomagnetic storms: Probabilistic forecasts and their uncertainties

Extreme space weather events are low-frequency, high-risk phenomena. Estimating their rates of occurrence, as well as their associated uncertainties, is difficult. In this study, we derive statistical estimates and uncertainties for the occurrence rate of an extreme geomagnetic storm on the scale of the Carrington event (or worse) occurring within the next decade. We model the distribution of even
Authors
Pete Riley, Jeffrey J. Love

Global statistical maps of extreme-event magnetic observatory 1 min first differences in horizontal intensity

Analysis is made of the long-term statistics of three different measures of ground level, storm time geomagnetic activity: instantaneous 1 min first differences in horizontal intensity ΔBh, the root-mean-square of 10 consecutive 1 min differences S, and the ramp change R over 10 min. Geomagnetic latitude maps of the cumulative exceedances of these three quantities are constructed, giving the thres
Authors
Jeffrey J. Love, Pierdavide Coisson, Antti Pulkkinen