Solar EUV index for aeronomical studies at earth from Langmuir probe photoelectron measurements on the Pioneer Venus Orbiter

Journal Article · Wed Jul 01 04:00:00 EDT 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA00384· OSTI ID:7262129

Hoegy, W R ^[1]; Mahajan, K K ^[2]

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1. NASA Goddard Space Flight Center, Greenbelt, MD (United States)
2. National Physical Lab., New Delhi (India)

The authors present a solar EUV index for aeronomical studies at Earth, obtained from the Langmuir probe measurement of photoelectron current on the Pioneer Venus orbiter (PVO). When the probe is in the solar wind and is negatively biased, the current, I{sub pe}, is mainly due to the impact of solar EUV photons with energies above the work function of the probe. I{sub pe} thus measures the total EUV flux over the wavelength interval from about 30 nm to Lyman alpha; on Venus this solar flux, V{sub EUV}, was defined by Brace et al. (1988). When translated to the solar longitude of Earth, for Earth use, it is called E{sub EUV}. To examine the potential of E{sub EUV} as a solar EUV flux index, they study the behavior of ionospheric parameters f{sub 0}E,f{sub 0}F{sub 1}, and f{sub 0}F{sub 2} at mid-latitude stations and compare their relationship with E{sub EUV} and with the 10.7-cm solar radio flux. They find f{sub 0}F{sup 1} and f{sub 0}F{sub 2} to be better correlated with E{sub EUV} than with the 10.7-cm flux. However, f{sub 0}E is better correlated with the 10.7-cm flux, because the 10.7-cm flux is also a proxy for soft X rays, which are an important ionizing source in the E region. They also provide a table of the EUV index, E{sub EUV}, for the period February 12, 1979, through most of 1991 which extends in time the table (of Venus values) published earlier by Brace et al. (1988). The EUV index will continue to grow until the end of the PVO mission in late 1992.

• OSTI ID: 7262129
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A7; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMISTRY
COLLISIONS
COMPARATIVE EVALUATIONS
CORRELATIONS
EARTH ATMOSPHERE
EARTH PLANET
ELECTRIC PROBES
ELECTROMAGNETIC RADIATION
EVALUATION
EXTREME ULTRAVIOLET RADIATION
HEATING
IONIZATION
IONOSPHERE
LANGMUIR PROBE
MEASURING METHODS
ORIGIN
PHOTOCHEMISTRY
PHOTON COLLISIONS
PLANETARY IONOSPHERES
PLANETS
PROBES
RADIATIONS
SOLAR ACTIVITY
SOLAR FLUX
SOLAR RADIATION
SOLAR WIND
STELLAR RADIATION
THERMOSPHERE
ULTRAVIOLET RADIATION