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Indices - Ground Based - aa

aa IAGA-endorsed magnetic activity index

https://doi.org/10.25577/9z05-v751

2026-03-19 02:25:06Z

Index which purpose is to measure the amplitude of global geomagnetic activity during 3-hour intervals normalized to geomagnetic latitude ±50°. aa was introduced to monitor geomagnetic activity over the longest possible time period.

ISGI website at EOST; aa Citation: Mayaud, P.-N., Menvielle, M., & Chambodut, A. (2023). aa geomagnetic index. EOST. (Dataset). https://doi.org/10.25577/9z05-v751 License: CC BY-NC https://creativecommons.org/licenses/by-nc/4.0/

Online

Open

CSV

Thank you for acknowledging the use of AMDA in publications with wording like "Data analysis was performed with the AMDA science analysis system provided by the Centre de Données de la Physique des Plasmas (CDPP) supported by CNRS, CNES, Observatoire de Paris and Université Paul Sabatier, Toulouse". See the Rules of the road at https://amda.cdpp.eu/help/policy.html . Please acknowledge the Data Providers.

Online

Open

CSV

VOTable

CDF

PNG

Thank you for acknowledging the use of AMDA in publications with wording like "Data analysis was performed with the AMDA science analysis system provided by the Centre de Données de la Physique des Plasmas (CDPP) supported by CNRS, CNES, Observatoire de Paris and Université Paul Sabatier, Toulouse". See the Rules of the road at https://amda.cdpp.eu/help/policy.html . Please acknowledge the Data Providers.

PT3H

aa

aa

nT

Aa

Aa

Daily Mean of aa

nT