A Comparative Study of Metallic Ions in the Atmospheres of Earth and Mars

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Metals are injected into planetary atmospheres by the ablation of interplanetary dust particles. The major species (Fe, Mg and Na) exist as atoms and ions that are excellent tracers of dynamics and chemistry. This project will contrast the behaviour of these metals in the Martian and terrestrial atmospheres. On Earth, metals are observed by ground-based lidar, rocket-borne mass spectrometry, and from optical spectrometers on satellites. For Mars, NASA's MAVEN spacecraft is providing unprecedented measurements of metallic ions over much of the planet's ionosphere. This is because MAVEN's highly elliptical orbit permits sampling to unusually low altitudes. Surprisingly different behaviour in the metal ions has been observed, which is probably due to (at least) two factors: unlike the Earth which has a permanent magnetic field, Mars only has patches of crustal magnetism mainly in the southern hemisphere; and Mars has a CO2 - rather than an N2/O2 - atmosphere.This project will used global whole-atmosphere models of Earth and Mars to understand why the metals behave so differently. The objective will be to improve our understanding of the coupling between the neutral and ionized atmosphere. An important reason for doing so is to understand the effects of space weather on our atmosphere, both short-term perturbations and longer-term climatic influences. The two models that will be employed are WACCM-X, an extended version of the Whole Atmosphere Community Climate Model from the National Center for Atmospheric Research (Boulder, USA), and the LMD-Mars model from the CNRS in Paris. Both are available at Leeds. This project will provide a high level of specialist scientific training in: (i) the application of world-leading atmospheric chemistry-climate models; (ii) analysis and synthesis or large datasets; (iii) use of advanced High Performance Computing facilities.