Configuration of the nightside Venus ionopause

Journal Article · Tue May 01 04:00:00 EDT 1979 · Geophys. Res. Lett.; (United States)

DOI:https://doi.org/10.1029/GL006i005p00345· OSTI ID:6130169

Brace, L H; Taylor, Jr, H A; Cloutier, P A; Daniell, Jr, R E; Nagy, A F

Nightside measurements of electron and ion concentrations by instruments on the Pioneer Venus Orbiter have revealed an ionopause that is highly dynamic and whose global configuration is unexpectedly complex. Inbound crossings which occur at high northern latitudes encounter the ionpause at an average altitude of 870 km in the late afternoon sector. The average ionopause altitude increases slightly near 110/sup 0/ solar zenith angle, SZA, followed by a nightside compression to well below 500 km. The outbound crossings of the ionopause occur about 20/sup 0/ south of the equator. The ionopause at this latitude is found at an average altitude of 800 km in the afternoon-evening sector between 65/sup 0/ and 110/sup 0/ SZA, followed by a pronounced rise to altitudes as high as 3000 km in a pronounced bulge near 130/sup 0/ SZA. A gradual decrease in average ionopause height occurs between 130/sup 0/ and 150/sup 0/ SZA with the lowest ionopause heights observed beyond 150/sup 0/. Superposed on this average behavior is an orbit to orbit variability of height at high and low latitudes near the terminator appears to confirm the asymmetry of the obstacle and shock surface observed by the Venera spacecraft and earlier predicted on the basis of theortical arguments. The post-terminator bulge of the ionopause at the equator and its extreme inward movemnet on the nightside are qualitatively consistent with the same type of theoretical arguments but require in addition the existence of strong electric fields that penetrate to very low altitudes in the cavity behind Venus.

• Research Organization: NASA/Goddard Space Flight Center, Laboratory for Planetary Atmospheres, Greenbelt, Maryland 20771
• OSTI ID: 6130169
• Journal Information: Geophys. Res. Lett.; (United States), Journal Name: Geophys. Res. Lett.; (United States) Vol. 6:5; ISSN GPRLA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CHARGED PARTICLES
ELECTRIC FIELDS
ION DENSITY
ION DRIFT
IONS
NITROGEN IONS
OXYGEN IONS
PIONEER SPACE PROBES
PLANETARY ATMOSPHERES
PLANETS
PLASMAPAUSE
SPACE VEHICLES
VENUS PLANET