The dependence of peak electron density in the ionosphere of Mars on solar irradiance

Previous studies of the Mars ionosphere have concluded that increased solar flux leads to increased peak electron densities. Many have described this relationship as N-m F-k, where N(m)is the peak electron density, F, the ionizing flux, is represented by either F-10.7 or E-10.7, and k is an exponent. The derived exponents have varied greatly, but have a mean value of k similar or equal to 0.35. Here, we explore this relationship using solar spectra measurements from the TIMED-SEE instrument and Mars Global Surveyor radio occultation data. Our derived exponents, k similar or equal to 0.50, are larger than those found by previous studies that used F(10.7)or E(10.7)and are close to the theoretical prediction of simplistic Chapman theory.