Impacts of the Martian crustal magnetic fields on the thermosphere, ionosphere, and hot oxygen corona
Abstract
A quantitative evaluation of the atmospheric loss at Mars is crucial to understanding the time-dependent inventory of water. Nonthermal mechanisms such as dissociative recombination of molecular ions result in the formation of the hot corona in the upper thermosphere and exosphere, where the escape of heavy neutral atoms occurs. Since Mars does not have an appreciable intrinsic magnetic field, its atmosphere is exposed to the direct interaction with the solar wind. The discovery of crustal magnetization at Mars by Mars Global Surveyor (MGS) shows that the crustal magnetic fields play a role in variation of the ionospheric content and the transport of ions in the upper atmosphere. These crustal magnetic fields may influence the production of hot oxygen atoms from dissociative recombination of O2+, which is the dominant source of hot oxygen at the current epoch. In this study, we investigate the effects of the Martian crustal magnetic fields on the hot oxygen corona by examining the impacts on the horizontal and vertical structure of the ionosphere and the resulting loss rates of hot oxygen from the hot oxygen corona in the upper atmosphere. To describe the upper atmosphere self-consistently, our 3D Adaptive Mesh Particle Simulator (AMPS) is one-way coupled with the 3D Mars Global Ionosphere Thermosphere Model (M-GITM), a newly developed thermosphere/ionosphere model. The crustal magnetic fields are prescribed in new M-GITM simulations. Subsequently, the structure and spatial variation of the ionosphere and hot oxygen corona are compared to those simulated without the inclusion of the crustal fields. The coupled framework provides the macroscopic properties of the resulting hot oxygen corona and estimates the global oxygen loss rates for the conditions considered. These results are also important and are being used to contribute to the investigation of the solar wind interaction with the Martian upper atmosphere. This work has been supported by grant NNX09AL26G from the Mars Fundamental Research Program.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #46
- Pub Date:
- November 2014
- Bibcode:
- 2014DPS....4630601L