NeMars: An empirical model of the martian dayside ionosphere based on Mars Express MARSIS data

Abstract

Several models of the martian ionosphere have been developed in the last years. In this paper, a new empirical model for the dayside electron density of the martian ionosphere (primary and secondary layer), called NeMars, is described. The model is mainly based on MARSIS AIS data (Active Ionospheric Sounding from the Mars Advanced Radar and Ionospheric Sounding experiment aboard Mars Express mission) and to a lesser extent on radio occultation data from the Mars Global Surveyor mission. The model is able to reproduce to a reasonable degree the main characteristics of the electron density profiles obtained with the two techniques by considering solar zenith angle, solar flux F-10.7 as a proxy of the solar activity, and heliocentric distance. The model partially assumes the Chapman theory, the scale height for the main layer of the model varies with the solar zenith angle and the altitude, and the Chapman-like photochemical processes dominate diffusion up to about 200 km altitude. In addition, we assess the level of importance that parameters like heliocentric distance, solar longitude, solar activity or solar zenith angle have on the formation of the ionosphere. Eventually, we compare the Total Electron Content (TEC) derived from NeMars model with the values obtained from the MARSIS radar operating in subsurface mode.