Investigation of Ionospheric Diurnal Double Maxima over Bangladesh

The diurnal double maxima (DDM) patterns in the total electron content (TEC) of the ionosphere have been inves-tigated using multiple station observations over Bangladesh. The daily TEC changes in the ionosphere are examined using global navigation satellite (GNSS) TEC data from 2020 to 2022. Descriptive statistics are involved in examining the monthly and seasonal variation of the occurrence rate of ionospheric DDM. To identify the possible disturbance sources responsible for ionospheric DDM, different periods are selected for study when DDM is observed at two of the TEC observing stations. The results show that the occurrence rate is higher in December, January, and February, but a drastic fall occurs in March and April in all three years. June and July have the second-highest ionospheric DDM incidence rate. Furthermore, the occurrence rate of ionospheric DDM is higher in winter and monsoon compared to pre-monsoon and post-monsoon. This study also found that the disturbance storm time (DST) index and the auroral electrojet (AE) magnetic activity index, which are related to ionospheric DDM, show storm and sub-storm signals.