| Autor: |
Qin, JunFeng, Curry, Shannon, Mitchell, Dave, Xu, Shaosui, Lillis, Robert, Andersson, Laila |
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| Zdroj: |
Geophysical Research Letters; Nov2024, Vol. 51 Issue 22, p1-12, 12p |
| Abstrakt: |
We investigate how the Martian dayside ionospheric structure is modified by crustal magnetic field (CMF) strength and upstream solar wind pressure by analyzing electron density data from the Langmuir Probe and Waves instrument onboard the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft. We find that the electron density above the exobase is anticorrelated with the ratio of solar wind's normal dynamic pressure (PSW⊥ ${P}_{\text{SW}\perp }$) to CMF magnetic pressure (PCMF ${P}_{\text{CMF}}$). We also analyze the electron density behavior across different magnetic topologies as a function of PSW⊥/PCMF ${P}_{\text{SW}\perp }/{P}_{\text{CMF}}$. The extremely low electron density in the draped topology relates to ionopause‐like structures. The lower electron density in the closed and open topology under higher PSW⊥/PCMF ${P}_{\text{SW}\perp }/{P}_{\text{CMF}}$ may be attributed to a downward force, potentially the J × B force in the case of closed topology. This study highlights the complex interplay between solar wind and CMF in influencing the Martian dayside upper ionosphere. Plain Language Summary: Mars is unique in the solar system because it lacks a global dipole field like Earth and instead has crustal magnetic fields (CMF, i.e., pockets of magnetic fields unevenly distributed on its surface). Such a magnetic scenario yields a very special picture of the interaction between solar wind (a stream of charged particles from the Sun) and the Martian upper atmosphere. For decades, people have found that the structure of the Martian ionosphere (an ionized layer in its upper atmosphere) can be heavily influenced by solar wind dynamic pressure (ram pressure of the stream of charged particles) and CMF strength, but the physics behind this is unclear. Our results indicate that the competition between the solar wind dynamic pressure and CMF strength can induce electromagnetic force, which affects the electron density in the Martian ionosphere. This study sheds light on the detailed physics of the interaction between solar wind and CMF and its implication for the behaviors of the Martian ionosphere. Key Points: The electron density in the Martian dayside upper ionosphere is anticorrelated with pressure ratio of solar wind to crustal magnetic fieldThe electron density in closed, open, and draped topology behaves differently as a function of this ratioThe J × B force may play an important role in the effect of crustal magnetic field and solar wind conditions on the Martian upper ionosphere [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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