Observation of TEC perturbation associated with medium-scale traveling ionospheric disturbance and possible seeding mechanism of atmospheric gravity wave at a Brazilian sector

In the present study, we document daytime total electron content (TEC) disturbances associated with medium-scale traveling ionospheric disturbances (MSTIDs), on few chosen geomagnetically quiet days over Southern Hemisphere of Brazilian longitude sector. These disturbances are derived from TEC data obtained using Global Navigation Satellite System (GNSS) receiver networks. From the keograms and cross-correlation maps, the TEC disturbances are identified as the MSTIDs that are propagating equatorward-eastward, having most of their average wavelengths longer in latitude than in longitude direction. These are the important outcomes of the present study which suggest that the daytime MSTIDs over Southern Hemisphere are similar to their counterparts in the Northern Hemisphere. Another important outcome is that the occurrence characteristics of these MSTIDs and that of atmospheric gravity wave (AGW) activities in the thermosphere are found to be similar on day-to-day basis. This suggests a possible connection between them, confirming the widely accepted AGW forcing mechanism for the generation of these daytime MSTIDs. The source of this AGW is investigated using the Geostationary Operational Environmental Satellite system (GOES) and Constellation Observing System for Meteorology, Ionosphere, and Climate satellite data. Finally, we provided evidences that AGWs are generated by convection activities from the tropospheric region.