The long-term behavior of the main peak of the dayside ionosphere of venus during solar cycle 21 and its implications on the effect of the solar cycle upon the electron temperature in the main peak region

Journal Article · Sun Oct 01 04:00:00 EDT 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA10p13339· OSTI ID:5833581

Kliore, A J; Mullen, L F ^[1]

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1. California Institute of Technology, Pasadena (USA)

One hundred four measurements of the peak electron density in the dayside ionosphere of Venus (solar zenith angle (SZA) <80{degree}), along with 11 Venera 9-10 measurements, were analyzed in order to establish the response of the dayside peak to the varying solar EUV flux over the maximum to minimum phase of solar cycle 21 (December 1979 to December 1986). The relationship of the peak electron density normalized to SZA = 0{degree} and the EUV flux index was found to be N{sub m} = N{sub 150}(F{sub EUV}/150){sup 0.376}, which is in agreement with theoretical predictions based on Chapman theory modified for photochemical processes. The corresponding dependence on solar zenith angle at any given value of F{sub EUV} was found to be N{sub m}(SZA) = N{sub 0}cos{sup 0.511} (SZA). The altitude of the peak was found to be independent of either SZA or F{sub EUV}. When the CO{sub 2}{sup +} production rate P{sub CO{sub 2{sup +}}} was computed using the Venus International Reference Atmosphere (VIRA) upper atmosphere model and the EUV flux computed from Hinteregger's (1981) formulae, it was found that the theoretically expected value of 0.5 for {Delta} log (N{sub m}/T{sub e}{sup 0.275})/{Delta} log (P{sub CO{sub 2{sup +}}}) was not obtained. Instead, when the assumption was used that T{sub e} = T{sub n} at the altitude of the peak, and the solar cycle corrections given in the VIRA model were applied, a log-log slope of 0.454 {plus minus} 0.010 was obtained, and a value of 0.485 {plus minus} 0.009 resulted when the VTS3 Venus thermosphere model (Hedin et al., 1983) was used. This suggested that the assumption T{sub e} = T{sub n} is not satisfactory.

• OSTI ID: 5833581
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A10; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics &amp; Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
DATA ANALYSIS
ELECTROMAGNETIC RADIATION
ELECTRON DENSITY
ELECTRON TEMPERATURE
EXTREME ULTRAVIOLET RADIATION
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMISTRY
PLANETARY IONOSPHERES
PLANETS
RADIATIONS
SOLAR CYCLE
SOLAR FLUX
SPACE VEHICLES
ULTRAVIOLET RADIATION
VARIATIONS
VEHICLES
VENERA SPACE PROBES
VENUS PLANET