Earth Planets Space, Vol. 63 (No. 4), pp. 327-333, 2011
M. Mosert1, L. A. McKinnell2,3, M. Gende4, C. Brunini4, J. Araujo5, R. G. Ezquer6,7,8, and M. Cabrera6
1Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (ICATE)CONICET, Av. España 1512 (Sur), CC 467, 5400 San Juan, Argentina
2Hermanus Magnetic Observatory, Hermanus 7200, South Africa
3Department of Physics and Electronics, Rhodes University, Grahamstown 6140, South Africa
4FCAG, Observatorio Astronomico, UNLP, Paseo del Bosque 1900, La Plata, Argentina
5Instituto Antártico Argentino, Dirección Nacional del Antártico, Cerrito 1248, Ciudad Autónoma de Buenos Aires, Argentina
6CIASuR, Facultad Regional Tucumán, Universidad Tecnológica Nacional, Argentina
7Laboratorio de Ionósfera, Dpto. de Física, FACET, Universidad Nacional de Tucumán, Av. Independencia 1800, CP 4000, Tucumán, Argentina
8Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Argentina
(Received May 31, 2010; Revised November 24, 2010; Accepted January 16, 2011; Online Online published June 14, 2011)
This paper presents a preliminary analysis of the variations of the critical frequency of the F2 region (foF2) and the total electron content (TEC) derived from Global Positioning System (GPS) data. Hourly foF2 values were scaled from ionograms recorded at San Martin (68.1°S, 293.0°E) and the TEC values were derived from GPS observations at O´Higgins (63.3°S, 302.5°E). The database includes measurements obtained under different seasonal and solar activity conditions. The study shows that the daily peak of foF2 occurs around local noon in winter and fall, and in spring a secondary peak is observed around midnight. In summer (January) foF2 reaches its minimum value around the noon sector while the maximum in the diurnal variation of foF2 is located in a time sector close to midnight. This behaviour is observed at low and high solar activity. The semiannual anomaly appears around noon at high and low solar activity and the winter anomaly is not observed. The effect of the solar activity is generally observed in every season. The analysis of the GPS TEC measurements in the same region indicates that the diurnal, seasonal and solar activity variations are similar to those observed in the foF2 values. An analysis of the performance of the IRI model to predict foF2 is also shown using the two IRI options (URSI and CCIR). The comparisons between the experimental values and the IRI predictions show some discrepancies.
Key words: Ionosphere, high latitude, IRI, foF2, GPS TEC.