Resumo

VAN ZELE, María Andrea. La fase principal de las tormentas geomagnéticas y la anomalía geomagnética del Atlántico Sur. Geoacta [online]. 2012, vol.37, n.2, pp.167-177. ISSN 1852-7744.

The aim of this study is to determine whether the rapid growth of the magnetic field intensity during the main phase of a geomagnetic storm(dB) depends on the intensity of the main field where it is recorded. For this storm variations calculated with in and outside the South Atlantic Geomagnetic Anomaly (SAMA), where the main geomagnetic field is minimal, are compare. From Vassouras (VSS, Brazil) observatory records, storm variations at the Anomaly area are calculated. Observatory records from Kourou(KOU) at the same longitude and conjugate geomagnetic latitude, and Kakadu (Australia) and Kanoya (Japan), at 180° of longitude and higher latitudes, are used for comparison. Geomagnetic storms registered between 2000 and 2009, with a well defined main phase according to Dst index, regardless their intensity, and lasting atleast a half an hour, are selected. It is established that a) the general characteristics recorded at the SAMA look like as those recorded outside; b) usually, the north component X rapid decrease is greater in VSS, but not in dependent of the start time or the season of year, c) usually storm variation of the total field(dB) is higher at VSS, but not independent of the start time or season. It can be concluded that where the total magnetic field is about a half of the corresponding to the dipole field, the rapid growth of the geomagnetic storm intensity during the main phase (dB) has a unique behavior associated with the intensity of the main field.

Palavras-chave : Geomagnetic storm; South Atlantic Magnetic Anomaly.

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