Solar wind interaction with the Martian upper atmosphere: Crustal field orientation, solar cycle, and seasonal variations

Abstract

A comprehensive study of the solar wind interaction with the Martian upper atmosphere is presented. Three global models: the 3‐D Mars multifluid Block Adaptive Tree Solar‐wind Roe Upwind Scheme MHD code (MF‐MHD), the 3‐D Mars Global Ionosphere Thermosphere Model (M‐GITM), and the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M‐AMPS) were used in this study. These models are one‐way coupled; i.e., the MF‐MHD model uses the 3‐D neutral inputs from M‐GITM and the 3‐D hot oxygen corona distribution from M‐AMPS. By adopting this one‐way coupling approach, the Martian upper atmosphere ion escape rates are investigated in detail with the combined variations of crustal field orientation, solar cycle, and Martian seasonal conditions. The calculated ion escape rates are compared with Mars Express observational data and show reasonable agreement. The variations in solar cycles and seasons can affect the ion loss by a factor of ∼3.3 and ∼1.3, respectively. The crustal magnetic field has a shielding effect to protect Mars from solar wind interaction, and this effect is the strongest for perihelion conditions, with the crustal field facing the Sun. Furthermore, the fraction of cold escaping heavy ionospheric molecular ions [( and/or )/Total] are inversely proportional to the fraction of the escaping (ionospheric and corona) atomic ion [O+/Total], whereas and ion escape fractions show a positive linear correlation since both ion species are ionospheric ions that follow the same escaping path.

Mars‐solar wind interaction: LatHyS, an improved parallel 3‐D multispecies hybrid model

“…Simulated escape rate estimates span values between 0.2 and 3.7 × 10 24 ions s −1 . These estimates are consistent with estimates deduced from observations [e.g., Brain et al , ], which include all ions above 30 eV, and other global simulations [e.g., Ma and Nagy , ; Dong et al , ]. For a given run, the reconstructed escape rate from the three methods varies by 18 to 36%, which confirms the quasi‐stationarity of the simulation.…”

“…The 1‐D and 3‐D ionospheric models [ Krasnopolsky , ; Fox , ; González‐Galindo et al , ] which have a much better spatial resolution and a complete description of the ionospheric chemistry are more appropriate. A first approach used by several global models [ Ma et al , ; Brecht and Ledvina , ; Dong et al , ] is to simplify the ionospheric description and limit the chemical reactions to the most important ones. We focus on the two main neutral species of the Martian atmosphere (CO 2 and O) below the exobase level (∼200 km height), the three major ion species (O , CO , and O + ) and the main associated chemical reactions [ Krasnopolsky , ].…”

“…One of the first models used a magnetogasdynamic approach [ Spreiter and Stahara , ]. Since then, more sophisticated models have been developed with different formalisms such as multispecies MHD [e.g., Ma et al , , ; Ma and Nagy , ; Terada et al , ; Ma et al , ], multifluid MHD [e.g., Harnett and Winglee , ; Najib et al , ; Riousset et al , ; Dong et al , , , ], and hybrid models [e.g., Modolo et al , , , ; Kallio et al , ; Brecht and Ledvina , ; Bößwetter et al , ]. Another approach is to use test particle models to study the properties and the dynamic of a specific ion population [e.g., Chaufray et al , ; Fang et al , ; Curry et al , , ; Poppe and Curry , ].…”

Pressure and ion composition boundaries at Mars

“…The solar wind inputs are specified as follows: a density of 4 cm −3 , a plasma temperature of 3.5 × 10 5 K, a velocity of 400 km/s, and the interplanetary magnetic field (IMF) being 3 nT in a typical away sector (IMF pointing away from the Sun) Parker spiral pattern with an angle of 56°. These inputs correspond to Case 17 of Dong et al [].…”

The Propitious Role of Solar Energetic Particles in the Origin of Life

“…In addition, extreme space weather events also enhance atmospheric loss due to erosion by the solar/stellar wind (Dong et al 2014(Dong et al , 2015a(Dong et al ,b, 2017a(Dong et al , 2018Jakosky et al 2015;Ma et al 2017). In fact, if the atmosphere is altogether depleted in O(100) Myr (Dong et al 2017b;Lingam & Loeb 2017e), there might not be sufficient time for life to originate and evolve (Lingam & Loeb 2017f,b); see Spiegel & Turner (2012) for a detailed Bayesian discussion of the constraints on the characteristic timescale for abiogenesis.…”