We report observations of sporadic-E (Es) layers and visual meteor count data simultaneously observed during night-time over the Arabian Peninsula. A constant and well-established presence of Es has been reported with a consistent count of meteors also present throughout the 1-year observation period. Data show that the Es observations are not dependent on the presence of meteor flux; i.e., the presence of meteors is not the main cause of the presence of Es over the Arabian Peninsula.

In this paper, the receiver differential code bias (DCB) of BDS (BeiDou Navigation Satellite System) is estimated as the changing parameter within 1 d with epoch-by-epoch estimates. The intraday variability of receiver DCB is analyzed from 30 d of Multi-GNSS Experiment observations. In particular, the intraday stability of receiver DCB for the BDS-3 and BDS-2 observations is compared. The result shows that the intraday stability of BDS-3 receiver DCB is better than that of BDS-2 receiver DCB.

This study correlates ionospheric parameters with the integrated solar radiation for an analysis of the delayed ionospheric response in order to confirm previous studies on the delay and to further specify variations of the delay (seasonal and spatial). Results also indicate the dependence on the geomagnetic activity as well as on the 11-year solar cycle. The results are important for the understanding of ionospheric processes and could be used for the validation of ionospheric models.

In this work, we studied the HILDCAA disturbance time effects in the TEC by analyzing local time and seasonal dependences, and the influences of the solar wind velocity on a sample of 10 intervals occurring in 2015 and 2016. The main results show great variability in the hourly distribution of the dTEC between one interval and another, seasonal behavior different from that presented by geomagnetic storms, and interestingly no relation between the dTEC disturbances and the magnitude of the HSS.