Studies of coincident solar, interplanetary, and terrestrial phenomena which precede certain geomagnetic storms

Abstract

Studies are made of solar, interplanetary, and terrestrial phenomena prior to each of the geomagnetic storms which occurred during a 14-month period of minimum solar activity. There are sufficient data available to suggest a model or mechanism by which energy capable of producing storms and other geomagnetic field changes is transferred from the sun to the earth. Furthermore, there exists a characteristic activity at mid-geomagnetic latitudes which precedes and thus apparently predicts some of the storms, Analysis shows this activity, termed a precursor, to be more than coincidental and to fit into a proposed model of solar-terrestrial energy transfer and storm generation, The precursor, which occurs in association with a polar magnetic substorm, is attributed to an ionospheric-magnetospheric current system. Relationships are given between the fine structure of the precursor and the time to-- and characteristics of-- the associated storm.