Copyright WDC C1 for STP at RAL.
AE stands for Auroral Electroject indices of magnetometer values measured round the North Pole. Both hourly and minute data are available here at RAL.
AE and related indices were devised by T N Davis and M Sugiura and first published in their "JGR" paper in 1966. The AE data's hourly average AE data indices have been derived by several different groups, some using different techniques. The AE indices begin in July 1957 at the start of the International Geophysical Year (IGY) and continue through to the present.