Conjugate All-sky Imagers to Study Ionospheric Processes from Low to Sub-auroral Latitudes

Optical observations from a chain of all-sky imagers (ASIs) in the 70° W longitudinal sector are used to investigate the electrodynamical coupling between both hemispheres. We use pairs of magnetically conjugate ASIs at mid and sub-auroral latitudes. Distinctive features found in the American longitude sector that can affect the inter-hemispheric behavior of the thermosphere/ionosphere include the presence of the South Atlantic magnetic anomaly and the large offset between magnetic and geographic latitudes. The processes discussed here involve low latitude equatorial spread-F (ESF) structures, medium scale traveling ionospheric disturbances (MSTIDs) and, at higher latitudes, stable auroral red (SAR) arcs. Complementary information is obtained from SuperDARN data, in-situ satellite measurements, and data from GPS receivers. The results show that the main inter-hemispheric differences are observed at low latitudes. This study represents initial attempts toward a comprehensive understanding of thermosphere/ionosphere processes from low to sub-auroral latitudes obtained with networks of instruments able to measure local and magnetically conjugate parameters simultaneously.