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

Abstract

We present a statistical study of the physical properties of Medium Scale Traveling Ionospheric Disturbances (MSTIDs) registered over the Mexican territory during 2018 and 2019 (solar minimum). The analysis is based on Total Electron Content (TEC) approximations using data from the ground-based Global Navigation Satellite System (GNSS) receivers at different locations divided into three regions according to geomagnetic coordinates: North, Center, and South. The MSTIDs were classified into day and night events, and only geomagnetically quiet days were considered to reduce the solar influence. We explored fundamental aspects of the MSTIDs, such as differences between day and night events, occurrence patterns, and geographical differences. Our results show some similarities with the occurrence periods of gravity waves, exhibiting a high activity during summer and winter. For this period, however, most events occurred between 20:00 PM and 04:00 AM UT. Moreover, the disturbances’ energy was stronger (i.e., large amplitudes and power) around the sunset terminator for the three regions. This suggests that the density gradient generated when the sunlight falls benefits MSTIDs formation.