Study on the relationship between the residual 27 day quasiperiodicity and ionospheric Q disturbances

In this paper, the relationship between the residual 27 day quasiperiodicity (QP) and Q disturbances is studied using three methods. Two Q disturbances identified by the monthly median method (MMM) and the commonly used 27 day running median centered method (RMC) show significant diurnal variation but are seen quiet in the same period when the spectral whitening method (SWM) is used. Further analysis indicates that diurnally varying Q disturbance events tend to appear in the extreme value position (EVP) of QP, which are the Q disturbance events related to QP. And their percentages are 81.8% for RMC and 95.6% for MMM but 0% for SWM. By studying the power spectrum, it suggests that the QP is the significant frequency component in the frequency domain of RfoF2‐RMC and RfoF2‐MMM (RfoF2 denotes to the relative deviation of foF2). However, there are no obvious periodic components in RfoF2‐SWM. Finally, to further verify whether the QP can contribute to common Q disturbance events, band‐pass filtering is used to extract the QP at different stations. The occurrence percentages of Q disturbances in the EVP of QP thus obtained with MMM and RMC are higher than with SWM for 90% of the stations. In addition, the average occurrence percentage based on RMC (37.5%) is also significantly higher than the percentage of EVP (23.2%). These findings suggest that the limitations of traditional methods lead to a significant QP in their results and that this residual QP may cause artificial Q disturbances. Key Points The relationship between the residual 27 day quasiperiodicity and Q disturbance is studied based on three methods Ionospheric disturbance derived by MMM and RMC remains a significant 27 day quasiperiodicity The 27 day quasiperiodicity is proved to contribute to Q disturbances