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- Title
The Low‐Altitude Ionosphere of the Ice Giant Planets.
- Authors
Molina‐Cuberos, G. J.; Witasse, O.; Toledo, D.; Tripathi, S. N.
- Abstract
The study of atmospheric electricity of the lower stratosphere and upper troposphere of the ice giant planets can help to understand several physical phenomena such as cloud formation, lightning generation, aerosols growth, or chemical composition. At these depths, galactic radiation is the main energy source able to ionize the atmospheric constituents and to produce a low altitude ionospheric layer that can be similar in magnitude to the upper ionosphere produced by solar radiation and auroral electrons. The presence of aerosols affects the ion‐neutral chemistry by capturing electrons and ions depending on the aerosol size and number density. Here, we present a new one dimensional ionospheric model of Uranus and Neptune able to calculate the number densities of electrons and ions as well as the charging of aerosols between 100 Pa and 4 × 105 Pa. Since the results depends upon the amount and size of the atmospheric aerosols, as well as on the flux of the incoming cosmic radiation, several aerosol models, solar‐cycle conditions, and the effect of the intrinsic magnetic field are considered. Plain Language Summary: Uranus and Neptune form the group of ice giant planets in our solar system. They are mainly composed of hydrogen, helium, and volatiles. These planets are the only ones that have not had a dedicated mission to study their atmospheres in situ. The most valuable information was obtained during the Voyager 2 encounters in 1986 and 1989. Such missions provided a wealth of information and raised important questions that have not been addressed yet. Here, we present a new model to calculate the density of electrical charges in the low‐altitude atmosphere in order to estimate electrical conductivity. We found that a low‐altitude ionosphere is created by cosmic radiation. The presence of aerosols can reduce the amount of electrons by more than three orders of magnitude compared to an aerosol‐free atmosphere. The results of this study can help to understand several important atmospheric processes, such as the formation of aerosols and clouds, as well as the generation of lighting. Key Points: A state model of ions and electrons in the lower ionosphere of Uranus and Neptune has been developedThe size and density distribution of aerosols strongly affect the number density of electrons and ionsThe measurement of the electrical conductivity can be used to study the lower ionospheres of Uranus and Neptune
- Subjects
GAS giants; ELECTRICAL conductivity measurement; COSMIC rays; ATMOSPHERIC electricity; IONOSPHERE; ATMOSPHERIC aerosols; OCCULTATIONS (Astronomy); ATMOSPHERIC nucleation
- Publication
Journal of Geophysical Research. Planets, 2023, Vol 128, Issue 3, p1
- ISSN
2169-9097
- Publication type
Article
- DOI
10.1029/2022JE007568