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

Autor(es)

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]

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: Annales Geophysicae; v. 36, n. 1, p. 139-147, JAN 25 2018.
• Citações Web of Science: 2

Resumo

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)

• Processo FAPESP: 12/08445-9 - Estudo da variabilidade dia-a-dia da mesosfera, termosfera e ionosfera em baixas latitudes e região equatorial, durante o ciclo solar 24
• Beneficiário: Paulo Roberto Fagundes
• Modalidade de apoio: Auxílio à Pesquisa - Temático