The effect of the solar cycle on the maintenance of the nightside ionosphere of Venus

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

DOI:https://doi.org/10.1029/91JA00672· OSTI ID:5316960

Kliore, A J ^[1]; Luhmann, J G ^[2]; Zhang, M H.G. ^[3]

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1. California Inst. of Tech., Pasadena (USA)
2. Univ. of California, Los Angeles (USA)
3. Austrian Academy of Sciences, Graz (Austria)

Pioneer Venus radio occultation measurements of the nightside ionosphere of Venus collected from 1979 to 1986 have made it possible to study its behavior at times of both solar maximum and solar minimum. Although some solar maximum measurements are similar in nature to those observed at solar minimum, which have an average peak density of about 7 {times} 10{sup 3} cm{sup {minus}3}, others show much higher peak densities, reaching values of about 4 {times} 10{sup 4} cm{sup {minus}3}. These elevated peak densities also occur at higher altitudes. The integrated electron column densities for these measurements are also much higher, indicating the presence of substantial ionization above the main peak. The magnitudes of both the peak density and the integrated content above the peak are anticorrelated with the solar wind dynamic pressure, leading to the interpretation that these enhancements during solar maximum are due to transterminator transport of O{sup +} ions from the dayside when the solar wind dynamic pressure is low enough to permit a sufficiently high dayside ionopause. The resulting ionization peak can be many times the concentration produced by energetic electron fluxes impacting the neutral atmosphere on the nightside, which apparently form the remaining source of the nightside peak at such times during solar maximum, when transterminator flow is cut off by high solar wind pressure depressing the dayside ionopause, and during solar minimum, when the ionopause is always depressed.

• OSTI ID: 5316960
• Journal Information: Journal of Geophysical Research; (United States), Vol. 96:A7; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
VENUS PLANET
PLANETARY IONOSPHERES
ALTITUDE
CHARGED-PARTICLE TRANSPORT
CORRELATIONS
ELECTRON DENSITY
IONIZATION
OXYGEN IONS
PIONEER SPACE PROBES
PLASMA DENSITY
PLASMA PRESSURE
PRESSURE EFFECTS
SOLAR CYCLE
SOLAR WIND
CHARGED PARTICLES
IONS
PLANETS
RADIATION TRANSPORT
SOLAR ACTIVITY
SPACE VEHICLES
VEHICLES
640107* - Astrophysics & Cosmology- Planetary Phenomena