Incoherent scatter radar study of the impact of the meteoric influx on nocturnal E-region ionization

We use the Arecibo incoherent scatter radar data collected from 1987 to 1995 to study meteoric impact on the nocturnal E-region electron/ion content. The nighttime ionization is observed to increase after midnight, which we interpret to be due to increase in background meteoric input. The column incremental rate due to meteoric ionization between 0100 to 0600 LT is estimated to be 10(9)/cm(2)/hr. Direct meteoric deposition is responsible for 60% of the total ionization in the morning hours in the altitude range of 97 to 114 km. Although there appears to be an increase in electron content during shower periods, there is not an one-to-one relation between meteor showers and E-region ionization enhancement.