Three‐dimensional multifluid simulations of ionospheric loss at Mars from nominal solar wind conditions to magnetic cloud events

Abstract

Three‐dimensional multifluid simulations of the solar wind interaction with a magnetized Mars are used to determine both the effect of the crustal magnetic field on ionospheric loss rate and the ionospheric loss rate as a function of solar wind conditions. Ionospheric losses on the order of 1025 O2+ ions per second are found for quiet solar wind conditions. This is of the same order as that estimated from Phobos 2 measurements. Varying the orientation of Mars' magnetic anomalies relative to the incident solar wind direction leads to only minor variation in the ionospheric loss rates of O2+ for each set of solar wind conditions studied. Solar wind parameters were varied from nominal solar wind conditions to conditions with high‐speed flows, high densities, and large IMF magnitudes. Outflow rates on the order of 1026 O2+ ions per second were seen for storm‐like conditions. The simulations indicate that ionospheric outflow rates increase by a larger percentage for high solar wind number density when compared to high solar wind speed or strong IMF conditions alone. This is due to the higher solar wind density and temperature of the precipitating ions. The results also indicate a significant influence of pickup on ionospheric loss.