TDIM ionospheric model TEC, hmF2, and NmF2 at mid-latitude northern hemisphere, used in the paper titled "Is TEC a Viable Servo Input?"

The externally imposed vertical drift in the F region is an extremely important driver of ionospheric dynamics but is very difficult to measure or map. Ionospheric servo algorithms have used hmF2 as F-region observable to infer the vertical drift. However, an even more plentiful observable is the total electron content (TEC) whose coverage over northern mid-latitudes has both spatial and temporal availability that matches those of the probable mechanisms responsible for vertical drift dynamics.

This ionospheric, first principle physics, study shows that TEC is a viable servo parameter at mid-latitudes in the noon sector. The servo relationship is shown to be linear over at least one hour for vertical drifts between + 100 m/s. Simulations over a full range of seasons and the solar cycle confirm the linear relationship between TEC and vertical drift with changing linear rate coefficients. These simulation results are dependent upon the vertical drift adopted to generate a baseline ionosphere from which the servo simulations evolve. Thus this type of TEC servo would generate relative vertical drifts. These, in turn, would create latitude-longitude maps of the vertical drift dynamics.