Analysis of Sq long-term changes at low latitudes

BLAS F. DE HARO BARBAS; ANA G. ELIAS; MARTA ZOSSI DE ARTIGAS

Buenos Aires

Workshop; 7th Workshop on Long-Term Changes and Trends in the Atmosphere; 2012

FACEYT - UNT

The Sq variation of the horizontal intensity, H, of magnetic observatories at low latitudes is analyzed, in search of significant long-term trends. These trends are expected based on increasing concentrations of greenhouse gases and the secular variations of the Earth’s magnetic field (B) which affect Sq through their effect over some of its main variables, like ionospheric conductivities and E-region electron concentration. The hourly geomagnetic field horizontal component, H, for the period 1960-2000, was analyzed. The solar activity effect was filtered out from Sq variation of H and then linear trends were assessed. The fact that the secular variation of B at the stations considered is not a uniform linear trend for the whole period was taken into account, as well as the alternating movement of the magnetic dip equator that is away or toward the station for different sub-periods. Our results are compared to those of other authors from Kyoto and Nagoya University, who made a similar analysis.