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Properties of Mars' Dayside Low-Altitude Induced Magnetic Field and Comparisons with Venus
  • Susanne Byrd,
  • Zachary Girazian,
  • Suranga Ruhunusiri
Susanne Byrd
University of Iowa

Corresponding Author:[email protected]

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Zachary Girazian
The University of Iowa
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Suranga Ruhunusiri
University of Iowa
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Mars and Venus have atmospheres but lack large-scale intrinsic magnetic fields. Consequently, the solar wind interaction at each planet results in the formation of an induced magnetosphere. Our work aims to compare the low-altitude (< 250 km) component of the induced magnetic field at Venus and Mars using observations from Pioneer Venus Orbiter (PVO) and Mars Atmosphere and Volatile EvolutioN (MAVEN). The observations from Mars are restricted to regions of weak crustal magnetism. At Venus, it has long been known the vertical structure of the induced magnetic field profiles have recurring features that enable them to be classified as either magnetized or unmagnetized. We find the induced field profiles at Mars are more varied, lack recurring features, and are unable to be classified in the same way. The solar zenith angle dependence of the low-altitude field strength at both planets is controlled by the shape of the magnetic pileup boundary. Also, because the ionospheric thermal pressure at Venus is often comparable to the solar wind dynamic pressure, the induced fields are weaker than required to balance the solar wind by themselves. By contrast, induced fields at Mars are stronger than required to achieve pressure balance. Lastly, we find the induced fields in the magnetized ionosphere of Venus have a weaker dependence on solar wind dynamic pressure than the induced fields at Mars. Our results point to planetary properties, such as planet-Sun distance, having a major effect on the properties of induced fields at nonmagentized planets.
15 Dec 2023Submitted to ESS Open Archive
27 Dec 2023Published in ESS Open Archive