Атты III халықаралық ғылыми-тәжірибелік конференция жинағЫ
жүктеу/скачать 8,11 Mb. Pdf көрінісі
|
III TOM
|
Abstract A solar flare typically produces immediate increases in the ionospheric ionization of varying degree at different heights, which are called the Sudden Ionospheric Disturbances (SIDs) or the ionospheric solar flare effects. In the present study of ionospheric solar flare effects through variation of ionospheric TEC, four different solar flare events during the solar minimum period for the year 2017 have been chosen. Key words: GPS, TEC, SIDs, The partially ionised region of the Earth‘s upper atmosphere, which extends from ~50 km above the surface of the Earth to ~1000 km, is called the ionosphere.The ionosphere is mainly formed by the interaction of solar X-ray and EUV ionizing radiation with neutral atmospheric constituents. Cosmic radiation also contributes to the formation of the ionosphere, but to a lesser extent [1,2,3,4,5]. However, the incident solar radiation‘s energetic photons interact with neutral atoms andmolecules in the upper atmosphere, giving the outer electron of such neutralspecies enough energy to escape the attraction of the positively charged nucleus. Ionospheric perturbations are mainly triggered by solar activity such as solar flares and coronal massejections, which have impinged on the terrestrial magnetosphere-ionosphere system. These event saffect the outermost geomagnetic field lines and compress the geomagnetic field causing geomagnetic disturbances. A solar flare can be defined as the sudden and explosive release of energy (~ 10 19 - 10 25 J) from a localized active region of the Sun ususlly near a complex group of sunspots, mainly in the form of electromagnetic radiaton across the entire spectrum. Solar flares and coronal mass ejections (CMEs) are the result of the sudden release of magnetic stresses accumulated for some period of time in the lower solar atmosphere. A strong outburst of solar activity occurred on 2017 September 4–10, when approaching a minimum of Cycle 24. It was due to the sharp development and evolution of the active region12673 during its passage across the western half of the visible disk. Numerous strong flaresoccurred at this time, including 27 M-class and 4 X-class flares. Among the latter, the X9.3 flareon September 6 was the most powerful in the last 10 years. It is not surprising that this activityand associated space weather disturbances arouse great interest, and many publications havealready been devoted to their study. A small fraction of the solar energy it is also hidden in the corona by large magnetic field frozen in huge plasma loops; these loops and strings are often dancing, connecting and reconnecting, leading to rare huge energy explosions in bright x-ray flare and exceptional mass ejection of solar particle burst, wind or flares. One of the brightest of this event had occurred very recently, just a year ago on 6th Sepetember 2017, as here shown in the x-ray figures: see Fig. 1 and by its time evolution peaks in Fig. 2. |