Aurora, Potential Gradient and Magnetic Disturbance

Abstract

IN view of suggestions which have been made from time to time that a relationship may exist between the intensity of the earth's electric field and the phenomena of the aurora, or of terrestrial magnetism, the available data from Cape Evans—the winter quarters of Capt. Scott's last expedition—have been examined. The original intention to make a comparison between the auroral data and the potential gradient data was formed on the publication of the first meteorological volume. This intention was stimulated by the fact that the time of maximum of the daily variation in potential gradient at that station lay between the time of maximum frequency for auroræ (4 A.M.) and the time of maximum magnetic disturbance (10 A.M.)—in time of the 180th meridian. In addition, Dr. Simpson had recorded slight anomalies in temperature and in pressure at the time of day when the aurora was most frequently observed. By the courtesy of Dr. Simpson, copies of the original data for potential gradient were made available, but it was found that the hours during which conditions were favourable both for observations of aurora and for potential gradient measurement (wind less than 10 miles per hour) were not sufficiently numerous to repay investigation.