Statistical analysis of TEC perturbations over a low latitude region during 2009-2013 ascending solar activity phase

摘要

Total Electron Content (TEC) perturbations are manifestations of ionospheric irregularities which induce fluctuations in the amplitude and phase of trans-ionospheric radio signals. TEC data derived from Global Positioning System (GPS) receivers at Mbarara (Geogra. -0.60°N, 30.74°E and Geomag. -10.22°N, 102.36°E) and Entebbe (Geogra. 0.04°N, 32.44°E and Geomag. -9.53°N, 104.10°E) from 2009 to 2013 were used to study TEC perturbations over the low latitude region of Uganda. The results show that the frequency of occurrence of TEC perturbations of ＞4 TECU increased steadily from 2009 to 2013. TEC perturbations with amplitude ＜4 TECU occurred at all times. The likelihood of TEC perturbations exceeding 6 TECU was higher during the equinoxes than during the solstices in most of the years. Comparison of TEC perturbations with 10.7 cm solar radio flux (F10.7) data showed a weak positive correlation with this solar proxy. Wavelet analysis performed on the TEC perturbations revealed wave-like oscillations with periods typical of Traveling Ionospheric Disturbances (TID). These wave-like structures (WLS) dominated from 13:00 to 19:00 LT for most of the years analyzed. Though the WLS were observed to increase with solar activity, no seasonal pattern was recorded in their occurrence.