Latitude-dependent delay in the responses of the equatorial electrojet and Sq currents to X-class solar flares
| Autor: | M. A. Abdu, P. A. B. Nogueira, Jonas Rodrigues de Souza, Ana P. M. Silva, João P. Serra de Souza da Costa, Paulo França Barbosa Neto, Clezio Marcos Denardini |
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| Rok vydání: | 2018 |
| Předmět: |
Atmospheric Science
010504 meteorology & atmospheric sciences Astrophysics::High Energy Astrophysical Phenomena Flux Astrophysics 7. Clean energy 01 natural sciences Latitude law.invention law Electric field 0103 physical sciences Earth and Planetary Sciences (miscellaneous) Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics Physics::Atmospheric and Oceanic Physics 0105 earth and related environmental sciences Physics Solar flare Geology Astronomy and Astrophysics Equatorial electrojet 13. Climate action Space and Planetary Science Extreme ultraviolet Physics::Space Physics Ionosphere Flare |
| Zdroj: | Annales Geophysicae. 36:139-147 |
| ISSN: | 1432-0576 |
| Popis: | We have analyzed low-latitude ionospheric current responses to two intense (X-class) solar flares that occurred on 13 May 2013 and 11 March 2015. Sudden intensifications, in response to solar flare radiation impulses, in the Sq and equatorial electrojet (EEJ) currents, as detected by magnetometers over equatorial and low-latitude sites in South America, are studied. In particular we show for the first time that a 5 to 8 min time delay is present in the peak effect in the EEJ, with respect that of Sq current outside the magnetic equator, in response to the flare radiation enhancement. The Sq current intensification peaks close to the flare X-ray peak, while the EEJ peak occurs 5 to 8 min later. We have used the Sheffield University Plasmasphere-Ionosphere Model at National Institute for Space Research (SUPIM-INPE) to simulate the E-region conductivity enhancement as caused by the flare enhanced solar extreme ultraviolet (EUV) and soft X-rays flux. We propose that the flare-induced enhancement in neutral wind occurring with a time delay (with respect to the flare radiation) could be responsible for a delayed zonal electric field disturbance driving the EEJ, in which the Cowling conductivity offers enhanced sensitivity to the driving zonal electric field. Keywords. Ionosphere (equatorial ionosphere) |
| Databáze: | OpenAIRE |
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