Figure 8. (a) Seasonal variability of the Total Electron Content measured by MARSIS; (b) the atmospheric density at 140 km given by the Mars Climate Database; (c) the column abundance of different species between 100 at 200 km given by the MCD; (d) the surface pressure measured by REMS/MSL; (e) the solar irradiance measured by TIMED-SEE and extrapolated to the Sun-Mars distance; and (f) the Sun–Mars distance. From Sánchez-Cano et al., 2018a, under Creative Common license CC-BY-4.