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Main Page   >   Данные   >   Geomagnetic Variations   >   Indices of geomagnetic activity   >   am, an and as indices

am, an and as Indices of Geomagnetic Activity

The three-hour am, an, as indices represent the perturbation amplitudes determined from the values of K index, defined on the same observatories, combined into groups, which are calculated Km, Kn, Ks indices of geomagnetic activity (see above).
The indices an, as and am are expressed in gammas.

Аm index is defined as the average of eight values of the index am per day.

The final values of the am index is calculated and made available by International Service of Geomagnetic Indices – ISGI Collaborating Institutes from data collected at magnetic observatories.

Download am, an, as indices for the period 1959 - 2013 in IAGA2002 format.

WDC for STP, Moscow is grateful to the ISGI Collaborating Institute EOST, Strasbourg, France, INTERMAGNET network and International Service of Geomagnetic Indices – ISGI (

Using the data, please be sure to indicate the above organizations according to the following tamplate.

Как цитировать наборы данных: Ball, A. and M. Duke [2011], How to cite datasets and link to publications, DCC How-to Guides, Edinburgh: Digital Curation Centre.

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