2.2.6 spase://CDPP/NumericalData/AMDA/Indices/Ground_Based/ground-based-am am am IAGA-endorsed magnetic activity index 2018-01-16T11:00:00Z Index which purpose is to provide a characterization of global geomagnetic activity using a large set of stations representing all longitudes and possible hemispheric discrepancies. ISGI website at EOST; License: CC BY-NC https://creativecommons.org/licenses/by-nc/4.0/ spase://CDPP/Person/Aude.Chambodut TechnicalContact IAGA geomagnetic indices http://isgi.unistra.fr/indices_am.php spase://CDPP/Repository/CDPP/AMDA Online Open AMDA at CDPP http://amda.cdpp.eu Text ISGI/UNISTRA spase://CDPP/Instrument/AMDA/Indices/Ground_Based MagneticField 1975-01-01T00:00:00Z 2018-06-15T21:00:00Z PT3H Earth.NearSurface am am am = (an + as)/2 nT Am Am Daily Mean of am nT