Hall Currents in the Aurora
In the eighteenth century, Anders Celsius noted that magnetic disturbances occurred during periods of auroral displays. At the end of the nineteenth century, Kristian Birkeland established magnetic observatories in northern Scandinavia, and determined that the “auroral” magnetic disturbances were caused by intense electric currents flowing horizontally above the earth’s surface in the as yet undiscovered ionosphere. These currents are now known to be Hall currents that flow perpendicular to both the earth’s magnetic field and intense electric fields which are generated at great distances from the earth. These Hall Auroral currents can be as large as one million amperes during periods when more power is deposited in the auroral zones than is generated in the entire United States. Numerous satellite, rocket, and ground-based observational programs are presently being directed toward an understanding of the auroral currents and how they are coupled to interplanetary space. Progress in understanding some of these phenomena is reviewed.
KeywordsSolar Wind Hall Current Hall Conductivity Auroral Zone Magnetic Disturbance
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