Mars ionosphere during two consecutive solar minima

Abstract

Mars Express has been exploring Mars since late 2003 giving us fascinating views of the red planet as well as unique science insights. The long-life of Mars Express is an asset in order to understand the long-term evolution of the atmosphere of Mars, and in particular, of the ionosphere and upper atmosphere. Currently, we have about 16 years of ionospheric observations at Mars, which cover near two cycles of solar activity. This is the first time that such a long time series observations can be investigated in other planet rather than Earth.  In particular, this work focuses on Mars’ ionospheric behaviour during two consecutive solar minima (23/24 and 24/25) using the same dataset. We use the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) on board Mars Express to investigate the total electron content behaviour of the whole atmosphere in relation to key parameters, such as the solar flux, solar illumination, dust storms and Sun-Mars distance. The topside variability of the ionosphere is also investigated through variations in the neutral scale height, and results are supported by ionospheric modelling. The main goal of this study is to investigate whether the ionosphere during the recent solar minimum 24/25 was similar (and to which degree) to the ionosphere at solar minimum 23/24, which was characterised by a pronounced reduction of both the topside and bottomside regions.