02/09/2026
By Lynne Schaufenbil
Mid-latitude Quiet-time Longitude Variations of Thermospheric Composition & Ionospheric Density
Katelynn Greer, Larisa Goncharenko, V. Lynn Harvey, Chihoko Cullens,
Understanding natural quiet-time variability is critical for understanding disturbed, or storm-time, conditions. This natural variability should not be mistaken for storm-driven variability. Further, most empirical models struggle to represent this quiet-time variability. Still, the quiet-time ionospheric structure exhibits pronounced longitudinal and local-time variability. We examined seasonal, quiet-time, mid-latitude total electron content (TEC) longitude and local time variations concurrently with three potential drivers: neutral winds, composition, and wind- induced vertical drift. Using an observational, systems approach, we jointly analyze mid-latitude total electron content (TEC) together with thermospheric winds and composition (O/N₂) from four instruments on three satellites during quiet periods in 2020 (low F10.7, low Ap, nominal polar-vortex state). Our results reveal the following: 1) neutral winds exhibit strong diurnal and seasonal variation, with notable longitudinal asymmetries that influence latitudinal advection and vertical plasma drift, 2) O/N₂ composition displays clear seasonal structure and significant longitudinal variability, some of which is driven by winds and some of which may be driven by wave-driven processes, and 3) vertical plasma drift, derived from the interaction between neutral winds and the geomagnetic field, explains many features of TEC variability not captured by composition or winds alone. These results provide an observational benchmark of mid-latitude quiet-time variability in winds, O/N2, and TEC across longitude and local time, providing a foundation for future model–data comparison studies.
If you are interested in attending, please email Lynne_Schaufenbil@uml.edu