Observation and Modeling of Multiple-Period Traveling Ionospheric Disturbances in the American Sector

Abstract:

We have used total electron content (TEC) values measured by several networks of GPS/GNSS receivers to investigate the characteristics and dynamics of TIDs in South and Central America. Analysis of TEC values observed between 2010 and 2016 shows that TIDs occur every day, are conjugate during the afternoon and early evening times and display multiple periodicities. Their phase velocities are predominantly away from the magnetic equator on both sides of the equatorial line containing a magnitude between 100 and 450 m/s. Although the TIDs occurrence exhibit a pronounced day-to-day variability, TIDs are present almost every day and every hour. Spectral and wavelet analysis of the TEC perturbations associated with TIDs show multiple periods varying between 10 and 120 minutes. TIDs with periods over 30 min occur concurrently and seem to be produced by the same train of GWs. TIDs containing periods as small as 10 min occur occasionally and sporadically. The latter TIDs show velocities that are different from the ones with a more extended period suggesting a different source and dynamics. This study demonstrates a possible relationship between these TIDs and lightning in the troposphere. We also show the results of a modeling effort to simulate the ionospheric response to the wind field related to the passage of atmospheric gravity waves.