A Study of the Morphology of Magnetic Storms: Moderate Magnetic Storms

摘要

Some average characteristics are determined for 136 moderate magneticud-- storms with sudden commencements that occurred during the intervalud-- 1902-1945. The average storm field is resolved for differentud-- epochs of storm time st into Dst, independent of local time, that is, ofud-- longitude X , relative to the sun, and into DS, that depends on X , Partud-- DS is expressed in terms of harmonic components with respect to X ,ud-- and like Dst, the amplitudes and phases of these components, are functionsud-- of st and of geomagnetic latitude. They are determined, for eachud-- of the three magnetic elements, declination, horizontal force, and verticalud-- force, at eight geomagnetic latitudes ranging from 80*N to 1°S. Inud-- the first, and main harmonic component of DS, its variations with respectud-- to storm time differs notably from that of Dst: its maximum isud-- attained earlier and its decay is more rapid. The storm -time changesud-- of the smaller harmonic components of DS have been less fully determined.ud-- The average characteristics of moderate storms are comparedud-- with those of weak storms.