MAGNETIC
STORMS
PATHWAYS

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Magnetic Storms

Magnetic storms occur when the radiation belts become filled with energetic ions and electrons. The drift of these particles produces a doughnut shaped ring of electrical current around the earth. The magnetic perturbations of this current are measured on the ground as a decrease in the magnitude of the horizontal component of the earth's magnetic field.. Magnetic storms are often initiated by the sudden arrival of a high speed stream of solar wind carrying high particle density and high magnetic field. If the solar wind field is southward prior to the arrival of the high pressure solar wind the earth's magnetotail may be loaded with magnetic energy and a violent magnetospheric substorm is immediately triggered. Such substorms often trigger transients on electrical power lines, telephone lines and north-south pipelines, and cause failures in these systems.

Nearly twenty years ago, Prof. McPherron and Prof. Russell collaborated in an important study that demonstrated that the Dst index which measures the strength of the storm time ring current could be predicted by the solar wind electric field and

dynamic pressure [button to IGPP List]. This result was originally summarized in the form of a differential equation, but has since been recast in the form of linear filters and neural networks. Only now are civilian and military agencies beginning steps to incorporate this important prediction technique into space weather forecasting. As a preliminary step both the Space Environment Laboratory of NOAA in Boulder, and the Air Force Space Weather Forecast Center in Colorado Springs are planning to calculate the Dst index in real time and predict it an hour ahead using upstream solar wind measurements. Prof. McPherron is collaborating with Professors R. Schunk and J. Sojka of the University of Utah in Logan, and Mr. Tom Detteman of NOAA to evaluate algorithms that calculate the Kp and Dst indices created with real time data. As part of this project Prof. McPherron is also evaluating techniques for generating quiet day traces (needed to obtain the disturbance variations). Prof. Gene Stringer of Southern Oregon State College, and Prof. Vince Wickwar of University of Utah are installing UCLA magnetometers provided by Prof. McPherron's group to measure midlatitude magnetic variations during magnetic storms.