Correlation between the global occurrences of ionospheric irregularities and deep atmospheric convective clouds in the intertropical convergence zone (ITCZ)

Abstract

To study the seeding mechanism of ionospheric irregularity occurrences, a correlation study has been carried out between the global monthly/latitudinal (m/l) distributions of irregularity occurrences and the deep atmospheric convective clouds in the intertropical convergence zone (ITCZ) indicated by the outgoing longwave radiation (OLR) measurements. Seven longitude sectors - the African, Indian, West Pacific, Central Pacific, East Pacific, South American, and Atlantic sectors - are selected to study the correlations between the two distributions. The results indicate that good correlations exist only in the South American sector and to some extent in the African sector. For the other five sectors, no correlations are found in the m/l distributions between the irregularities and OLRs. This implies that the gravity wave induced in the ITCZ cannot be the sole seeding agent for the Rayleigh-Taylor (RT) instability in the global irregularity occurrences every season. We suspect that the post-sunset ionospheric electrodynamic perturbations could be the prevailing seeds for the RT instability globally year long. Together with the favorable post-sunset ionospheric condition, the global m/l distributions of irregularity occurrences could be adequately explained.