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USGS Mendenhall Postdoctoral  Research Fellowship Program

14-28. Weathering the storm: The ground-level response to geomagnetic disturbance - GICs and critical infrastructure

figure 1Geomagnetically-induced currents (GICs) are produced by electric fields induced in the Earth during geomagnetic storms. GICs pose a significant risk to critical infrastructure as they flow along electric power-transmission systems and other electrically-conducting infrastructure. The great magnetic storm of March 1989, associated with one of the largest geomagnetic disturbances of the twentieth century, caused wide-spread blackouts across the Canadian Hydro-Quebec power grid, resulting in the loss of electric power to more than 6 million people (Czeck, 1992). If a similar storm-induced blackout occurred in the Northeastern United States, the economic impact would exceeded $10 billion (NRC, 2008; Baker, 2009), not counting the negative impact on emergency services and the reduction in public safety associated with the loss of electric power in large cities.

GIC levels are primarily driven by impulsive geomagnetic disturbances created by the interaction between the Earth’s magnetosphere and sharp velocity, density, and magnetic field enhancements in the solar wind. These disturbances result in ground-level time varying magnetic fields, which, when they reach large levels, produce GICs. During a typical 11-year solar cycle, geomagnetic changes in magnetic field are sufficiently severe to produce GICs on an average of 200 days (NERC, 2010). Modeling, however, the exact levels and spatial distribution of induced currents in power grid infrastructure during a geomagnetic event requires both knowledge of deep earth conductivity structure and transmission line design parameters (NERC, 2012).

Magnetic field measurements at the surface of the Earth are sometimes used to derive statistical estimates of the induced electric field response to magnetic impulses. These models are based on long time series K and aa indices, which are also commonly used to define operational thresholds for determining GIC threat levels (  Although these indices provide a continuous data source for statistical analyses, they are limited by their 3-hour time resolution, coarse spatial coverage, and maximum level saturation (NERC, 2012). Additional tools are needed that provide improved spatial and temporal resolution to better understand and specify the relationship between space weather events and induced currents in specific locations.

The goal of this project is to extend and improve existing electric field models for GIC applications using this data, as well as pursue relevant scientific questions on the nature and statistics of electric fields induced by geomagnetic disturbances such as magnetic storms and substorms.

Direct measurement of electric fields for GIC studies is difficult due to the wide range of geological structure and variable nature of the induced fields over areas of interest. However, local or regional estimates are critical to providing accurate hazard assessments to end users who may be affected by ground-level electric field variation (for example, power utilities).  The following data are available and may help in the pursuit of research under this Opportunity.

Electric field estimates are typically calculated in the frequency domain using surface impedance estimates, derived from local ground conductivity models, and the spectral characteristics of the magnetic field driver. Some of the uncertainties and scientific topics the successful applicant may choose to pursue might include:

  1. How accurate is a local estimate of the magnetic field based on observatory inputs; how important are spatial variations in the magnetic field to GIC calculations?
  2. How well do interpolation methods work for magnetic field inputs to electric field calculations?
  3. Are the existing one-dimensional conductivity models sufficient? Where are more advanced models needed?
  4. How significant are coastal and other transverse variations in conductivity to GIC calculations?
  5. What are the possible electric field values and GIC impacts of extreme geomagnetic events?


Baker, D. N. (2009), What Does Space Weather Cost Modern Societies?, Space Weather, 7, S02003, doi:10.1029/2009SW004

Czeck, P., H. Huynh, A Dutil (1992), The Hydro-Quebec System Blackout of 13, March, 1989: System Response to Geomagnetic Disturbance, Proceedings: Geomagnetically Induced Currents Conference, November 8-10, 1989, San Francisco. Published by the Electric Power Research Institute, EPRI-TR-100450, Editor B. Damsky, pages 19-1 to 19-21.

North American Electric Reliability Corporation (2010), High-Impact, Low-Frequency Event Risk to the North American Bulk Power System: A Jointly-Commissioned Summary Report of the North American Electric Reliability Corporation and the U.S. Department of Energy’s November 2009 Workshop.

North American Electric Reliability Corporation (2012), 2012 Special Reliability Assessment Interim Report: Effects of Geomagnetic Disturbances on the Bulk Power System.

National Research Council (2008), Severe Space Weather Events -- Understanding Societal and Economic Impacts: A Workshop Report, Washington, DC: The National Academies Press, Washington D.C.

Proposed Duty Station: Golden, CO

Areas of Ph.D.: The successful applicant will have a degree in earth sciences, physics, or related fields, preferably with a background in space physics, geophysics, or geomagnetism, with experience in numerical modeling (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet one of the following qualifications - Research Geologist, Research Geophysicist, Computer Scientist, Research Physicist, Research Mathematician.

(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of theposition will be made by the Human Resources specialist).

Research Advisor(s): Jeffrey Love, (303) 273-8540,;Paul Bedrosian, (303) 236-4834, pbedrosian@usgs; Jennifer Gannon, (303) 666-6738, ; Andrei Swidinsky (Colorado School of Mines), (303) 273-3934,

Human Resources Office Contact: Robert Hosinski, (916) 278-9397,

Go back to Summary of Opportunities

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Last modified: 10:21:15 Thu 25 Jul 2013
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