The effects of X-class solar flare monitored by ground-based GPS receivers

In this investigation, we present and discuss the observations of two X-class solar flares in 25 February 2014 and 19 October 2014. The solar flare events take place at the active region AR11990 and AR12192. For this investigation, we present the X-ray flux observed by geostationary operational environmental satellite (GOES) and total electron content (TEC) observations from Global Positioning System (GPS) satellites. From the collected data, it shows that quite amount of TEC observed during the solar flare events. The TEC observations for the February 25
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ranged from 20 to 81 TECU, while the TEC observations for the October 19
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ranged from 67 to 126 TECU. The comparison of X-ray flux data and TEC data is used to determine the responses between them. The results indicate that a solar flare begins with a dramatic increase in X-ray radiation, which correlates with a sustained increase in TEC measurements. Additionally, from the observations show that the TEC effect occurs when the X-ray flux increases exceed one hour. This work may contribute to a better understanding of the ionosphere's consequences of solar flares. Moreover, this investigation also improves the understanding of relation between TEC and X-ray flux.