Small-scale plasma, magnetic, and neutral density fluctuations in the nightside Venus ionosphere

Journal Article · Sun Apr 01 00:00:00 EST 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA04p04085· OSTI ID:5223106

Hoegy, W R; Brace, L H; Kasprazak, W T ^[1]; Russell, C T ^[2]

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1. NASA Goddard Space Flight Center, Greenbelt, MD (United States)
2. Univ. of California, Los Angeles (United States)

Pioneer Venus orbiter measurements have shown that coherent small-scale waves exist in the electron density, the electron temperature, and the magnetic field in the lower ionosphere of Venus just downstream of the solar terminator (Brace et al., 1983). The waves become less regular and less coherent at larger solar zenith angles, and Brace et al. suggested that these structures may have evolved from the terminator waves as they are convected into the nightside ionosphere, driven by the day-to-night plasma pressure gradient. In this paper the authors describe the changes in wave characteristics with solar zenith angle and show that the neutral gas also has related wave characteristics, probably because of atmospheric gravity waves. The plasma pressure exceeds the magnetic pressure in the nightside ionosphere at these altitudes, and thus the magnetic field is carried along and controlled by the turbulent motion of the plasma, but the wavelike nature of the thermosphere may also be coupled to the plasma and magnetic structure. They show that there is a significant coherence between the ionosphere, thermosphere, and magnetic parameters at altitudes below about 185 km, a coherence which weakens in the antisolar region. The electron temperature and density are approximately 180{degree} out of phase and consistently exhibit the highest correlation of any pair of variables. Waves in the electron and neutral densities are moderately correlated on most orbits, but with a phase difference that varies within each orbit. The average electron temperature is higher when the average magnetic field is more horizontal; however, the correlation between temperature and dip angle does not extend to individual wave structures observed within a satellite pass, particularly in the antisolar region.

• OSTI ID: 5223106
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:A4; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
VENUS PLANET
PLANETARY IONOSPHERES
ALTITUDE
CONVECTION
CORRELATIONS
ELECTRON DENSITY
ELECTRON TEMPERATURE
FLUCTUATIONS
GRAVITY WAVES
MAGNETIC FIELDS
PIONEER SPACE PROBES
PLASMA DENSITY
PLASMA PRESSURE
PRESSURE GRADIENTS
ENERGY TRANSFER
HEAT TRANSFER
MASS TRANSFER
PLANETS
SPACE VEHICLES
VARIATIONS
VEHICLES
640107* - Astrophysics & Cosmology- Planetary Phenomena