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Statistical Study of Magnetic Field Variations for Mapping of Hazardous Effects: Karen J. Remick


Project Title: Statistical Study of Magnetic Field Variations for Mapping of Hazardous Effects
Mendenhall Fellow: Karen J. Remick, (303) 273-8475, kremick@usgs.gov
Duty Station: Golden, Colorado
Start Date: October 4, 2004
Education: Space Physics at University of Alaska – Fairbanks 2004
Research Advisor: Jeffrey Love, (303) 273-8540, jlove@usgs.gov
Project Description: Solar activity results in fast flowing plasma streams, shocks and magnetic clouds in the interplanetary medium. When they reach earth, these features cause magnetic storms. Magnetic storms are the magnetospheres way of processing the energy imparted to it by the solar wind. One of the most noticeable effects magnetic storms have on the near-earth environment is the enhancement of ionospheric polar electrical currents called the auroral electrojets. The picture below shows the visible result of currents running through the ionosphere. In addition to providing people in polar locations with a light show, these constantly changing ionospheric currents generate changing magnetic fields. Changing magnetic fields induce currents in any conducting material longer than a few 100 meters, such as power grids and telephone lines. These currents are called Geomagnetically Induced Currents (GICs). GICs can be responsible for large scale equipment failure, and was responsible for the 1989 black out of the entire Hydro Quebec system, which serves more than 6 million customers.

Photograph of magnetic storm     When determining the load on power lines or telephone systems, it would be helpful to be able to model the induced current. Unfortunately, the ionospheric currents are not stationary with respect to the earth and change in magnitude and location for a number of reasons. The Earth’s magnetic axis does not coincide with its rotational axis, thus the ionospheric currents, which form an oval, occur further south on the night side than on the dayside portion. During geomagnetically active times the auroral oval increases in diameter, moving the ionospheric currents further south as well as strengthening them. Thus locations normally too far south to be affected by the auroral currents can be hard hit by large storms. In addition to the spatial variations, the frequency and strength of magnetic storms changes with solar cycle and season. These factors make it difficult to determine what safety precautions are necessary to protect technological systems. This project seeks to create a hazard map by using over a decade of USGS magnetometer data to statistically determine the location and strength of the ionospheric currents for different times and geomagnetic conditions.



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Last modified: 16:08:32 Thu 13 Dec 2012