Journal article
Importance of Ambipolar Electric Field in Driving Ion Loss From Mars: Results From a Multifluid MHD Model With the Electron Pressure Equation Included
Journal of geophysical research. Space physics, Vol.124(11), pp.9040-9057
11/2019
DOI: 10.1029/2019JA027091
Abstract
The multifluid (MF) magnetohydrodynamic model of Mars is improved by solving an additional electron pressure equation. Through the electron pressure equation, the electron temperature is calculated based on the effects from various electron‐related heating and cooling processes (e.g., photoelectron heating, electron‐neutral collision, and electron‐ion collision), and thus, the improved model can calculate the electron temperature and the electron pressure force terms self‐consistently. Model results of a typical case using the MF with electron pressure equation included model are compared in detail to identical cases using the MF and multispecies models to identify the effect of the improved physics. We find that when the electron pressure equation is included, the general interaction patterns are similar to those with no electron pressure equation. However, the MF with electron pressure equation included model predicts that the electron temperature is much larger than the ion temperature in the ionosphere, consistent with both Viking and Mars Atmosphere and Volatile EvolutioN (MAVEN) observations. Using our numerical model, we also examined in detail the relative importance of different forces in the plasma interaction region. All three models are also applied to a MAVEN event study using identical input conditions; overall, the improved model matches best with MAVEN observations. All of the simulation cases are examined in terms of the total ion loss, and the results show that the inclusion of the electron pressure equation increases the escape rates by 50–110% in total mass, depending on solar condition and strong crustal field orientation, clearly demonstrating the importance of the ambipolar electric field in facilitating ion escape.
Key Points
For the first time, the effect of the ambipolar electric field is self‐consistently included in the global multifluid MHD model
The ambipolar electric field plays a significant role in driving ion loss from Mars. The ion mass loss can be enhanced by more than 50%
The improved model matches best with MAVEN observations in comparison with previous models
Details
- Title: Subtitle
- Importance of Ambipolar Electric Field in Driving Ion Loss From Mars: Results From a Multifluid MHD Model With the Electron Pressure Equation Included
- Creators
- Y. J. Ma - University of California, Los AngelesC. F. Dong - Princeton Plasma Physics LaboratoryG. Toth - University of MichiganB. Holst - University of MichiganA. F. Nagy - University of MichiganC. T. Russell - University of California, Los AngelesS. Bougher - University of MichiganXiaohua Fang - Laboratory for Atmospheric and Space PhysicsJ. S. Halekas - University of IowaJ. R. Espley - Goddard Space Flight CenterP. R. Mahaffy - Goddard Space Flight CenterM. Benna - Goddard Space Flight CenterJ. McFadden - University of California, BerkeleyB. M. Jakosky - Laboratory for Atmospheric and Space Physics
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.124(11), pp.9040-9057
- DOI
- 10.1029/2019JA027091
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 18
- Grant note
- NASA (NNH10CC04C)
- Language
- English
- Date published
- 11/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428769802771
Metrics
13 Record Views