Statistical Characteristics of the Occurrence of ERI and FRI in the Equatorial Ionosphere With Observations of JULIA Radar

摘要

Abstract Based on observations of the Jicamarca Unattended Long‐term investigations of the Ionosphere and Atmosphere (JULIA) radar, we perform statistical analysis on the occurrence of 3‐m‐scale E‐region irregularities and F‐region irregularities (FRI) in Jicamarca region of South America. The results show that there is a negative correlation between the occurrence rates of equatorial irregularities in E‐ and F‐region. When the equatorial spread F appears, the occurrence rate of irregularities in E‐layer decreases. By analyzing the ion zonal drift velocity detected by JULIA radar, it is proposed that the vertically polarized electric field in the bottom F‐layer could extend downward to E‐layer when FRI appears, leading to the weakening or even reversal of E‐layer electric field. As a result, the electron vertical drift velocity in the E‐layer decreases so as to suppress the growth rate of two‐stream instability, which cause a weakening or even disappearance of equatorial irregularities in E‐region.