The ionopause current layer at Venus

Journal Article · Mon Jul 01 00:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA00674· OSTI ID:5224600

Cravens, T E ^[1]; Shinagawa, H ^[2]

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1. Univ. of Kansas, Lawrence (USA)
2. Communications Research Lab., Ibaraki (Japan)

Magnetic fields are induced by the solar wind in the ionospheres of planets such as Venus and Mars, which possess only weak, or nonexistent, intrinsic magnetic fields. The magnetometer on the Pioneer Venus Orbiter (PVO) observed large-scale magnetic fields in the ionosphere when the solar wind dynamic pressure was high. During high solar wind dynamic pressure conditions the ionopause was observed to be broad and at low altitudes, whereas during low solar wind dynamic pressure conditions the ionopause was located at high altitudes (z > 300 km) and was narrow ({Delta}z {approx} 20 km). The authors review the results of recent theoretical models of the magnetic field in the ionosphere of Venus, and, in particular, the one-dimensional MHD model of Shinagawa and Cravens (1988) and the two-dimensional kinematic dynamo model of Cravens et al. (1990). The results of these models are used as a starting point for an explanation of the behavior of the ionopause. It is well known that during low solar wind dynamic pressure conditions the location of the ionopause is determined by vertical pressure balance between the ionospheric thermal pressure and the magnetic pressure of the overlying magnetic barrier. The structure of the ionopause is not well understood; they suggest that the sensitivity of horizontal plasma transport to the presence of a magnetic field and the convergence of the vertical flow provide the explanation for the narrowness of the Venus ionopause. However, during high solar wind dynamic pressure conditions, ion-neutral friction also plays an important role in determining the thickness of the ionopause.

• OSTI ID: 5224600
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:A7; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALTITUDE
DIMENSIONS
FRICTION
INTERACTIONS
MAGNETIC FIELDS
MARS PLANET
MATHEMATICAL MODELS
MORPHOLOGY
PIONEER SPACE PROBES
PLANETARY IONOSPHERES
PLANETS
PLASMA DRIFT
PLASMA PRESSURE
SOLAR ACTIVITY
SOLAR WIND
SPACE VEHICLES
THICKNESS
VEHICLES
VENUS PLANET