Equatorial ionospheric response to isolated aurora

Authors: Hajkowicz L A

Publish Date: 1996/09/30

Volume: 14, Issue: 9, Pages: 906-916

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Abstract

Abstract The equatorial ionospheric response to 228 isolated rapidonset auroral substorms as defined from the auroral electrojet index AE was found from enhancements of the virtual minimum height of the Fregion ∆hprimeF in the declining phase of a solar cycle 1980–85 The responses found for three longitudinal sectors at the equator Africa Ouagadougou and Dakar Asia Manila and America Huancayo were compared with the response close to the auroral source region at Yakutsk northern Siberia The auroral substorm onsets were centered at 17 and 15 UT at sunspot maximum 1980–82 and minimum 1983–85 preceding by 3–5 h the period of postsunset height rise in the African sector whereas other sectors were in the early afternoon Huancayo and morning Manila The African response particularly at Ouagadougou was distinctly different from other sectors In the sunspot maximum years 1980–81 the auroral surges were followed after about 3 h by a sharp depression ∆hprimeF0 in the postsunset height rise with a period of little or no response ∆hprimeF=0 in 1982 A response polarity reversal ∆hprimeF0 was noted in this sector for sunspot minimum 1983–85 when large hprimeF enhancements were observed at the sunset region The responses in the Asian and American sector were positive except for a case in Huancayo when response was negative following an auroral surge before the sunset at this station It appears that the aurorally generated largescale travelling ionospheric disturbances LSTIDs which first cause positive height enhancements in a subauroral location Yakutsk subsequently affect the unstable postsunset ionosphere in the equatorial Africa

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