A study of solar flare electromagnetic effects on the ionosphere of southern Brazil during solar cycle 23.

The solar x-ray radiation follows a behavior similar to the solar cycle activity, which results in periodic disturbances on the Earth's atmosphere. Among the most intense solar activity events are the solar flares: sudden, localized, transient increases in brightness caused by active regions near sunspots. The data analysis for investigation of this phenomenon can provide important information about the Sun/Earth interaction, Magnetospheric effects, as well as events occurring in the Ionosphere which may lead to disturbances in telecommunications, small satellites or even in the Space Weather. In this work we study the characteristics of high-intensity flares (X class) and its effects on the Earth occurred during the solar cycle 23 (1996 - 2007). For this purpose, we utilize X-rays data (in the range 0.5 to 8 A) from the GOES satellites (Geostationary Operational Environmental Satellites), as well as the equipments dedicated to study the Solar-Earth interactions at the Southern Space Observatory (SSO/CRS/INPE - MCT), (29°S, 53°W), Sao Martinho da Serra, RS, Brazil, such as riometer and magnetometer. With these tools, we search for any correlation between the solar activity and the ionospheric phenomenon, such as the Sudden Ionospheric Disturbance (SID), and magnetic crochet. These disturbances may cause sudden changes in the ionospheric density and variations in the components of the geomagnetic field that allow us to infer about the disturbed currents in the ionosphere.