Climatology of ionospheric scintillations and TEC trend over the Ugandan region

This study presents results on the investigation of the diurnal, monthly and seasonal variability of Total Electron Content (TEC), phase (_σΦ${\sigma }_{\mathrm{\Phi }}$) and amplitude (S4) scintillation indices over Ugandan (Low latitude) region. Scintillation Network Decision Aid (SCINDA) data was obtained from Makerere (0.34°N, 32.57°E) station, Uganda for two years (2011 and 2012). Data from two dual frequency GPS receivers at Mbarara (0.60°S, 30.74°E) and Entebbe (0.04°N, 32.44°E) was used to study TEC climatology during the same period of scintillation study. The results show that peak TEC values were recorded during the months of October–November, and the lowest values during the months of July–August. The diurnal peak of TEC occurs between 10:00 and 14:00 UT hours. Seasonally, the ascending and descending phases of TEC were observed during the equinoxes (March and September) and solstice (June and December), respectively. The scintillations observed during the study were classified as weak (0.1≤$\le$S4,_σΦ≤${\sigma }_{\mathrm{\Phi }}\le$0.3) and strong (0.3<$<$S4,_σΦ≤${\sigma }_{\mathrm{\Phi }}\le$1.0). The diurnal scintillation pattern showed peaks between 17:00 and 22:00 UT hour, while the seasonal pattern follows the TEC pattern mentioned above. Amplitude scintillation was more dominant than phase scintillation during the two years of the study. Scintillation peaks occur during the months of March–April and September–October, while the least scintillations occur during the months of June–July. Therefore, the contribution of this study is filling the gap in the current documentation of amplitude scintillation without phase scintillation over the Ugandan region. The scintillations observed have been attributed to wave-like structures which have periods of about 2–3 h, in the range of that of large scale travelling ionospheric disturbances (LSTIDs).