Journal article
Solar cycle and seasonal variability of the nightside ionosphere of Mars: Insights from five years of MAVEN observations
Icarus (New York, N.Y. 1962), Vol.393, p.114615
03/15/2023
DOI: 10.1016/j.icarus.2021.114615
Abstract
Using Mars Atmosphere and Volatile EvolutioN (MAVEN) observations from 2014 to 2019, we characterize how the structure and composition of the nightside ionosphere varies on solar cycle and seasonal timescales. At fixed altitudes between 150 and 200 km, plasma densities vary substantially on these timescales in response to variations in fixed thermospheric pressure levels, which cause the ionosphere to rise and fall in altitude. Additionally, solar cycle and seasonal trends in the electron impact ionization (EII) rate affects nightside densities; higher densities are observed near solar maximum and Mars perihelion (when EII rates are largest), and lower densities are observed near solar minimum and Mars aphelion (when EII rates are smallest). Lastly, densities in the high-altitude (>200 km) nightside ionosphere vary significantly over the solar cycle: topside O+ densities vary by a factor of ∼50 and topside O2+ densities vary by a factor of ∼40. Topside ion densities were relatively stable throughout the solar minimum of 2018–2019.
•Densities at fixed altitudes vary because the thermosphere expands and contracts.•Densities at fixed pressure levels vary with season and over the solar cycle.•Topside O+ and O2+ densities vary substantially over the solar cycle.
Details
- Title: Subtitle
- Solar cycle and seasonal variability of the nightside ionosphere of Mars: Insights from five years of MAVEN observations
- Creators
- Z. Girazian - University of IowaJ. Halekas - University of IowaR.J. Lillis - University of California, Berkeley
- Resource Type
- Journal article
- Publication Details
- Icarus (New York, N.Y. 1962), Vol.393, p.114615
- Publisher
- Elsevier Inc
- DOI
- 10.1016/j.icarus.2021.114615
- ISSN
- 0019-1035
- eISSN
- 1090-2643
- Grant note
- DOI: 10.13039/100000104, name: National Aeronautics and Space Administration, award: 80NSSC19K1219
- Language
- English
- Date published
- 03/15/2023
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984428780602771
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