Auroral Electrojet Index (AE)

The Auroral Electrojet Index, AE, is designed to provide a global, quantitative measure of auroral zone magnetic activity produced by enhanced Ionospheric currents flowing below and within the auroral oval. Ideally, It is the total range of deviation at an instant of time from quiet day values of the horizontal magnetic field (h) around the auroral oval. Defined and developed by Davis and Sugiura [1966], AE has been usefully employed both qualitatively and quantitatively as a correlative index in studies of substorm morphology, the behavior of communication satellites, radio propagation, radio scintillation, and the coupling between the interplanetary magnetic field and the earth's magnetosphere. For these varied uses, AE possesses advantages over other geomagnetic indices or at least shares their advantageous properties.

1. it can be derived on an instantaneous basis or from averages of variations computed over any selected interval;
2. it is a quantitative index which, in general, is directly related to the processes producing the observed magnetic variations;
3. its method of derivation is relatively simple, digital, and objective and is well suited to present computer processing techniques; and
4. it may be used to study either individual events of statistical aggregates.

These indices were and are derived in response to indications of need as voiced by the scientific user community in journal articles, at meetings in resolutions of national and international groups, and in personal communications.

For additional information on the AE index, please visit the WDC Kyoto Observatory .

The online system has indices for the years 1987 and 1988/January-June. To order other years contact the Data Center.

Selected years of AE are available for download from our FTP site