The Role of Sporadic E Layer in the Creation of Nighttime Medium-Scale Traveling Ionospheric Disturbances

This study investigates the source of nighttime medium-scale traveling ionospheric disturbances (MSTIDs) in middle latitudes by analyzing various satellite observation data. Our investigation focuses on the causal linkage between sporadic E (Es) and MSTIDs. Es is suggested as an important source of MSTIDs, but their correlation on the global scale has not yet been rigorously investigated. Application of satellite observations for the study of MSTIDs is increasing recent years. The advantage of satellite observations relative to ground-based observations is the provision of the global distribution of MSTIDs. We establish the occurrence climatology of MSTIDs using the measurements of the electron density by CHAMP and Swarm satellites. The occurrence climatology of Es is determined using the GPS occultation data provided by CHAMP and COSMIC missions. By investigating the day-to-day variability of MSTIDs and Es and their occurrence climatology we evaluate to what extent the creation of nighttime MSTIDs can be attributed to Es. Ground-based observations (total electron content and airglow observations) are used to support the interpretation of space-borne observation data.