MGS electron density profiles: Analysis and modeling of peak altitudes

► We have analyzed nearly all the MGS RO profile shapes and peak altitudes. ► We assign each RO profile to 1-4 types, and find a solar cycle variation for 2 types. ► We fit the peak densities versus ln(eff sec χ) and find non-Chapman behavior. ► We find that the E region peaks decreases in altitude with increasing F10.7. ► We analyze “data” from our numerical models and find non-Chapman behavior. ► We infer that the underlying thermosphere in the terminator region changes rapidly.