Disruption of E region echoes observed by the EAR during the development phase of equatorial spread F: a manifestation of electrostatic field coupling

Abstract

Simultaneous observations of E- and F- region irregularities made using the Equatorial Atmosphere Radar (EAR) are presented to study the coupling between the E- and F- region. The observations clearly suggest that the disruption of E region field aligned irregularities (FAI) over the EAR is closely associated with the development phase of equatorial plasma bubble. The observed coupling effects on the low latitude E region FAI during the development phase of equatorial bubble are found to be quite pronounced over the EAR. This is consistent with the fact that the E region over the EAR connects the F region over the equator, where strong polarization electric fields are generated in association with equatorial plasma bubble phenomenon. Relatively weak vertical downward electric field and large eastward polarization electric field associated with plasma density depletion in the evening equatorial ionosphere, which map to low latitude E region over the EAR, are proposed to be responsible for the inhibition of growth of irregularities.