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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Latitude-dependent delay in the responses of the equatorial electrojet and S-q currents to X-class solar flares

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Nogueira, Paulo A. B. [1] ; Abdu, Mangalathayil A. [2] ; Souza, Jonas R. [2] ; Denardini, Clezio M. [2, 3] ; Barbosa Neto, Paulo F. [2, 3] ; Serra de Souza da Costa, Joao P. [1] ; Silva, Ana P. M. [1]
Total Authors: 7
[1] Fed Inst Educ Sci & Technol Sao Paulo, Sao Paulo - Brazil
[2] Inst Nacl Pesquisas Espaciais, Div Aeron, BR-12227010 Sao Jose Dos Campos, SP - Brazil
[3] Inst Nacl Pesquisas Espaciais, Embrace Space Weather Program, BR-12227010 Sao Jose Dos Campos, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: Annales Geophysicae; v. 36, n. 1, p. 139-147, JAN 25 2018.
Web of Science Citations: 2

Ionosphere (equatorial ionosphere)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 S-q 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 S-q current outside the magnetic equator, in response to the flare radiation enhancement. The S-q 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. (AU)

FAPESP's process: 12/08445-9 - Study of day-to-day variability of the mesosphere, thermosphere and ionosphere at low latitude and equatorial region, during the solar cycle 24
Grantee:Paulo Roberto Fagundes
Support type: Research Projects - Thematic Grants