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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 29, issue 5
Ann. Geophys., 29, 865–873, 2011
https://doi.org/10.5194/angeo-29-865-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 29, 865–873, 2011
https://doi.org/10.5194/angeo-29-865-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

  18 May 2011

18 May 2011

Annual and semiannual variations of vertical total electron content during high solar activity based on GPS observations

M. P. Natali and A. Meza M. P. Natali and A. Meza
  • Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata Paseo del Bosque s/n, (1900), La Plata, Argentina
  • Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, Buenos Aires, Argentina

Abstract. Annual, semiannual and seasonal variations of the Vertical Total Electron Content (VTEC) have been investigated during high solar activity in 2000. In this work we use Global IGS VTEC maps and Principal Component Analysis to study spatial and temporal ionospheric variability. The behavior of VTEC variations at two-hour periods, at noon and at night is analyzed. Particular characteristics associated with each period and the geomagnetic regions are highlighted.

The variations at night are smaller than those obtained at noon. At noon it is possible to see patterns of the seasonal variation at high latitude, and patterns of the semiannual anomaly at low latitudes with a slow decrease towards mid latitudes. At night there is no evidence of seasonal or annual anomaly for any region, but it was possible to see the semiannual anomaly at low latitudes with a sudden decrease towards mid latitudes. In general, the semiannual behavior shows March–April equinox at least 40 % higher than September one. Similarities and differences are analyzed also with regard to the same analysis done for a period of low solar activity.

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