O I 630.0‐nm dayglow in the region of equatorial ionization anomaly: Temporal variability and its causative mechanism

Abstract

Results of the continuous measurements of O I 630.0‐nm dayglow from Mount Abu (20° 20′N dip latitude), a station in the region of equatorial ionization anomaly (EIA) by means of a recently developed ground‐based dayglow photometer are presented. The measurements on magnetically quiet and moderately active days reveal that there are strong noontime bite‐outs in 630.0‐nm intensities. The temporal variabilities in the intensities show a good correlation with those in electron densities in the lower F region over Ahmedabad (18° 23′N dip latitude) with a time delay of 1 hour. Theoretical estimation of the intensities indicates that the dissociative recombination of O 2 + with ambient electrons is mainly responsible for the observed temporal variability in the dayglow emission. The time delay between the theoretically evaluated and the measured noontime bite‐outs is discussed in the context of the development of the EIA.