Abstract
The growth and decay of the main phase of the September 21-23, 1963 magnetic storm are studied in detail on the basis of iso-intensity contour maps of the main phase field, which were generated by a computer.
It is shown that in contrast to the rather smooth variation of the Dst index during the storm period, the development of the main phase is quite dynamic. In particular, the deepest main-phase depression in the afternoon-evening sector evolves in a complex way, waxing and waning as magnetospheric substorms occur. Eventually, a fairly uniform main-phase depression results, as the deepest depression subsides rapidly and also spreads toward the least depressed sector.
In order to interpret these changes properly in terms of the growth and decay of distant (beyond the ionosphere) currents, similar analyses should be performed for future storms, in conjunction with space observations by several geostationary satellites.
