Abstract

VAN ZELE, María Andrea. The quiet geomagnetic variations sq and their relationship with solar parameters. Geoacta [online]. 2013, vol.38, n.1. ISSN 1852-7744.

The objective of this work is to verify if the quiet geomagnetic variations (Sq) recorded at African longitudes resemble these that were found at eastern observatories in relation with solar parameters. The solar geomagnetic variations during geomagneticaly quiet days (Sq) are due to the movement of particles at the ionospheric E region, and generated by the solar radiation impinging on them. Km indices are used for determining of the quietness of a day. SymH and SymD indices are used for eliminating the symmetric ring current and solar flux pressure on the magnetosphere. Sq variations of the choose days during a timespan [2000, 2007] recorded at BNG and HER were studied. To verify if the impinging solar radiation influences on the geomagnetic perturbation, F10.7 for quiet and disturbed days are compared, observing the existence of extreme values during high activity. Following other authors, a solar parameter deduced from F10.7 index (the F107DP(81)), is considered adequate as a proxy of the EUV radiation, considering a previous comparison with the MgII (an incomplete record). Later, the vertical projection of F107DP(81) on the observatory is computed (proyF107DP) according to the day of the year. Though the small number of selected days do not allow a Fourier analysis, it could be concluded that the Sq at HER (at mid latitude, into the SAMA) fulfill the characteristics found at the antipodes: the mean geomagnetic variation is smaller than in BNG (at low latitude), the solar radiation is an important contribution at the Sq variation according to the solar activity at both observatories; but it is not for the annual or semiannual variation; it should be conclude, as other authors, that the winds at the ionosphere are responsible of these last variations.

Keywords : Sq; Quiet geomagnetic variations; BNG; HER; Solar activity.

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