Substorms

Abstract

A magnetospheric substorm is a term ascribed to magnetospheric and ionospheric activity that takes place during an interval of time that begins with enhanced energy input from the solar wind into the magnetosphere and ends with a decrease of that energy input to its original value. The study of substorms breaks down into three major thrusts. First of all, there are the observations which have been well documented since the latter part of the 19th century. Secondly, there are the studies of the physical processes whereby energy from the solar wind enters the magnetosphere and is dissipated within geospace, that have been vigorously pursued since the early 1960's. As part of this effort, several different frameworks have been proposed, each based in the physics of magnetized space plasmas, that purport to reflect the way in which substorm activity develops. Finally, since the early 1980's, the evolution of high performance computing has led to the ability of researchers to simulate the magnetosphere-ionosphere system and to probe its response to changing solar wind conditions. In this chapter, we shall look at substorms in terms of the first two thrusts mentioned above. We shall begin by outlining the historical development of the substorm concept, which is essential for understanding how that concept developed as increasingly better data became available. Such an approach is necessary so older papers that contributed to the development of the context can be more critically assessed. © 2007 Springer-Verlag.