Evidence of the ionospheric response to the QBO

Abstract

The yearly intensity variation of the day‐to‐day variability of the equatorial ionization anomaly (EIA) has been investigated. It is revealed that this yearly intensity variation is weakly anticorrelated with the solar activity and geomagnetic aa indices but obviously modulated by the QBO (Quasi‐Biennial Oscillation): in the east phase of the QBO the day‐to‐day variability of the EIA increases; in the west phase of the QBO the day‐to‐day variability of the EIA decreases. These effects seem to imply that it is not the solar bursts and/or geomagnetic storms but other disturbances to which the day‐to‐day variability of the EIA is to be ascribed. A possible explanation for this phenomenon is proposed.