Climatology of Medium-Scale Traveling Ionospheric Disturbances (MSTIDs) Observed with GPS Networks in the North African Region

Abstract

We present for the first time the climatology of medium-scale traveling ionospheric disturbances (MSTIDs) by using Global Positioning System (GPS) receiver networks on geomagnetically quiet days (Kp ≤ 3) over the North African region during 2008–2016. The ionospheric Total Electron Content (TEC) were estimated from the dual-frequency GPS measurements, and the TEC perturbations (dTEC) data were derived from the estimated TEC data. We focused on the TEC perturbations (dTEC) associated MSTIDs and statistically analyzed its characteristics, occurrence rate, diurnal and seasonal behavior as well as the interannual dependence. The results show that MSTID is a local and seasonal dependence. The result reveals that occurrence of MSTIDs increases with solar activity. It also shows that MSTIDs predominantly propagates towards the South (equatorward). The MSTIDs event period is (12 ≤ period ≤ 53 min), while the dominant peak-to-peak amplitude is (0.08 ≤ amp ≤ ~ 1.5 dTECU). The study also shows that the amplitude of MSTIDs is higher at the northwest (Lat: ~ 32° N to ~ 38° N, Long: ~ 2° W to ~ 15° W) when compared with northeast (Lat: ~ 28° N to ~ 38° N, Long: ~ 23° E to ~ 40° E), and the disturbance occurrence time is more frequent within the hours of (1200–1600 LT), and (1000—1400 LT) in December solstice at daytime for stations located in the northwest and northeast part of the African region, respectively. While at the nighttime, the MSTIDs also exhibits variability in disturbance occurrence time around (northwest: 2100–0200 LT) and (northeast: 1900-0200 LT) in June solstice, but get extended to March equinox during solar maximum (2014). The mean phase velocity in daytime MSTIDs is higher than the nighttime in every season, except during June solstice.

Properties of Medium-Scale Traveling Ionospheric Disturbances Observed over Mexico During Quiet Solar Activity

“…This threshold value of the TIDs events was established by analyzing the standard deviation of all wave-like patterns identified in the MNIG station. Other authors have used threshold values between 0.07 -1 TECu [9,13,18], which agree with the value used in this work. It is important to mention that the amplitude was calculated using the mean value approximation between the upper and lower points of the disturbance, referred to as the average absolute amplitude.…”

The Role of Convectively‐Generated Gravity Waves in Poleward Propagation of MSTIDs Over Srinagar (34.1°N, 74.8°E)

“…Moreover, Oluwadare et al. (2022) pointed out that the MSTIDs can be potentially generated by the primary waves which survive the dissipation or can possibly be caused by secondary GWs or even both these waves can possibly propagate further up to the thermosphere. These authors also pointed out that lower atmospheric GWs with convective sources penetrate into the thermosphere as higher order GWs.…”

“…Vadas & Azeem (2021) suggested that during the convective processes, local body forces act onto the atmosphere which accelerates the neutral wind in the primary direction of GWs and sometimes also leads to the generation of secondary waves. Moreover, Oluwadare et al (2022) pointed out that the MSTIDs can be potentially generated by the primary waves which survive the dissipation or can possibly be caused by secondary GWs or even both these waves can possibly propagate further up to the thermosphere. These authors also pointed out that lower atmospheric GWs with convective sources penetrate into the thermosphere as higher order GWs.…”