Ion‐neutral chemistry model of the lower ionosphere of Mars

Abstract

[1] The ion neutral chemistry of the lower Martian atmosphere is more complex than any other ionospheric region and similar, in some aspects, to the terrestrial D region. Two ionization sources operate at these altitude levels: solar radiation, which is the most important one below around 70 km, and galactic cosmic radiation. The interaction of positive ions and electrons produced by these ionization sources with the Martian atmosphere, which is abundant in species able to be charged negatively, produces a high variety of positive and negative ions. We present here a new model of the ion chemistry developed to calculate the concentration of electrons and most abundant ions in the atmosphere of Mars below 100 km. The present knowledge of Mars' atmosphere allows us to include new neutral and ionic species, such as nitrogen derivated, in a more detailed ion-chemistry calculation than previous lower ionopheric models of Mars. We obtain that the electron density profile has a low-altitude secondary peak below the main photon-induced maximum. This peak is placed at around 35 km and is due to the high efficiency of the electron attachment to O x molecules, which entails that the concentration of negative ions is higher than that of electrons below around 30 km. The most abundant ionic species predicted are positive ions like hydronimum hydrates H 3 O + (H 2 O) n and O 2 + and negative ions like CO 3 À (H 2 O) n and NO 3 À (H 2 O) n .

Effect of dust storms on the D region of the Martian ionosphere: Atmospheric electricity

“…Neither in situ nor remote sensing measurements in the low-altitude daytime ionosphere are available at Mars. models have also confirmed that Mars has a permanent D region in the lower ionosphere [Whitten et al, 1971;Molina-Cuberos et al, 2001, 2002Haider et al, 2007Haider et al, , 2008Haider et al, , 2009aHaider et al, , 2009b]. Several theoretical 1 Physical Research Laboratory, Ahmedabad, India.…”

Applications of Electrified Dust and Dust Devil Electrodynamics to Martian Atmospheric Electricity

“…It decreases by more than two orders of magnitude compared to the simple model of ion-neutral chemistry of Molina-Cuberos et al (2002) to be less than ∼0.5 e cm −3 at ground with the ∼100 e cm −3 peak at 35 km lifted to ∼45 km, and also reduced by two orders of magnitude at ∼1 e cm −3 . Michael et al (2007 comprehensively modelled the role of aerosols on the charged particle distribution and conductivity in the lower atmosphere using aerosol properties (Chassefière et al 1995).…”

“…According to Molina-Cuberos et al (2002) the most abundant ions below ∼50 km are hydronium ions H 3 O + (H 2 O) n while O + 2 dominates above ∼70 km. The main negative ion species are water clusters of CO − 3 , NO − 2 , NO − 3 reaching a density of about 4500 ions cm −3 at the surface.…”

Advances in the aeronomy of Venus and Mars

“…The ionospheric D-regions of Mars has been modeled by Molina-Cuberos et al (2002) using a photochemical scheme that is similar to that of the terrestrial ionospheric D-region. Ionization by solar EUV and X-ray fluxes is dominant down to about 70 km and below that altitude ionization by cosmic rays becomes more important.…”