Journal article
Multi‐Fluid MHD Study of the Disappearing Solar Wind Event Observed by MAVEN: Effects of Solar Wind Density
Journal of geophysical research. Space physics, Vol.130(7), e2025JA033997
07/2025
DOI: 10.1029/2025JA033997
Abstract
Using the latest Mars Multi‐fluid Magneto‐hydrodynamic (MHD) model (Y. J. Ma et al., 2019, https://doi.org/10.1029/2019ja027091 ), we examined an extremely low solar wind density event observed by Mars Atmosphere and Volatile Evolution (MAVEN) on 26 December 2022. Simulation results show that the solar wind density plays a crucial role in plasma interactions. The interaction region expands significantly from less than 2 R M under typical solar wind density conditions to more than 4 R M along the subsolar line for extremely low solar wind density (<0.1 cm −3 ), consistent with MAVEN observations during the event. Under low solar wind density conditions, the ion pickup plume becomes smaller and is associated with a lower flow speed. Model results also show a nonlinear correlation between the solar wind density and the ion escape rates. Specifically, when the solar wind density is relatively high (>0.2 cm −3 ), the total ion loss rate positively correlates with the solar wind density. However, when the solar wind density is extremely low, ion escape rates are nearly constant despite further decreases in solar wind density. For this event, the solar wind density dropped by over an order of magnitude, while the MHD model predicts the total ion escape rate reduced by approximately a factor of ∼3. Additionally, we investigated possible reasons for the sudden drop in magnetic field strength during the inbound segment of two consecutive orbits and found that a sudden change of the interplanetary magnetic field direction to radial configuration could also attribute to the observed field decrease.
Global Magneto‐hydrodynamic simulations reveal how Mars‐solar wind interaction responds to extremely low solar wind density conditions Solar wind density plays a crucial role in influencing the size of the interaction region and the structure of the ion pick‐up plume The ion escape rates typically increase with solar wind density but remain nearly constant when the density is very low
Details
- Title: Subtitle
- Multi‐Fluid MHD Study of the Disappearing Solar Wind Event Observed by MAVEN: Effects of Solar Wind Density
- Creators
- Yingjuan Ma - University of California, Los AngelesJasper S. Halekas - Department of Physics and Astronomy University of Iowa Iowa City IA USAShaosui Xu - University of California, BerkeleyChristopher M. Fowler - West Virginia UniversityJanet G. Luhmann - University of California, BerkeleyXiaohua Fang - University of Colorado BoulderGabor Toth - Department of Climate and Space Sciences and Engineering University of MI Ann Arbor MI USAShannon Curry - University of Colorado Boulder
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.130(7), e2025JA033997
- DOI
- 10.1029/2025JA033997
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Publisher
- Wiley
- Grant note
- NASANASA through the Mars Exploration ProgramNational Science Foundation: 2400337
This work was supported by NASA Grant NNH10CC04C to the University of Colorado, with a subcontract to UCLA and UCB. The MAVEN project is supported by NASA through the Mars Exploration Program. X.F. and Y.M. acknowledge support through NASA Grant 80NSSC23K0882 and NASA Grant 80NSSC23K1358. This work was also partly supported by National Science Foundation under Grant 2400337.
- Language
- English
- Date published
- 07/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984865311902771
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