Mars Dust Storm Effects in the Ionosphere and Magnetosphere and Implications for Atmospheric Carbon Loss
Résumé
Mars regional and global dust storms are able to impact the lower/upper atmospheres through dust aerosol radiative heating and cooling and atmospheric circulation. Here we present the first attempt to globally investigate how the dust impact transfers from the neutral upper atmosphere to the ionosphere and the induced magnetosphere above 100-km altitude. This is achieved by running a multifluid magnetohydrodynamic model under nondusty and dusty atmospheric conditions for the 2017 late-winter regional storm and the 1971-1972 global storm. Our results show that the dayside main ionospheric layer (below ∼250-km altitude) undergoes an overall upwelling, where photochemical reactions dominate. The peak electron density remains unchanged, and the peak altitude shift is in accordance with the upper atmospheric expansion (∼5 and ∼15 km for the regional and global storms, respectively). Controlled by the day-to-night transport, the nightside ionosphere responds to the dust storms in a close connection with what happens on the dayside but not apparently with the ambient atmospheric change. At higher altitudes, dust-induced perturbations propagate upward from the ionosphere to the magnetosphere and extend from the dayside to the nightside, within a broad region bounded by the induced magnetospheric boundary. It is found that the global dust storm is able to dramatically enhance the CO2+ loss by a factor of ∼3, which amounts to an increase of ∼20% or more for total carbon loss (in the forms of neutrals and ions). Strong dust storms are a potentially important factor in atmospheric evolution at Mars.
Domaines
Planète et Univers [physics]
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JGR Space Physics - 2019 - Fang - Mars Dust Storm Effects in the Ionosphere and Magnetosphere and Implications for.pdf (25.38 Mo)
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