Interplanetary energetic ions and polar radio wave absorption

Journal Article · Sat Apr 01 04:00:00 EST 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA04p03543· OSTI ID:5915564

Armstrong, T P; Laird, C M ^[1]; Venkatesan, D ^[2]; Krishnaswamy, S; Rosenberg, T J ^[3]

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1. Univ. of Kansas, Lawrence (USA)
2. Univ. of Calgary, Alberta (Canada)
3. Univ. of Maryland, College Park (USA)

This is a study of the ionization input of interplanetary (including solar flare) energetic protons and alpha particles into the south polar ionosphere over the interval 1982-1985. It is well known that interplanetary ions have full and prompt access to the polar ionosphere. The incremental ionization produced at 20-120 km. altitudes causes enhanced radio wave absorption which is observed by riometers operated by the University of Maryland, at South Pole, Antarctica. The authors compute the expected absorption from the vertical structure of the ionization deposited by these energetic particles and compare the computed values with the observations. The contribution of the alpha particles is found to be quite small as a percentage of the absorption except at the peak of the day 35, 1983, event, when their contribution to the absorption is about 0.6 dB out of a total of 3.4 dB. The dominant contribution to absorption at 30 MHz usually arises from protons below 10 MeV, specifically in the 2- to 4-MeV interval. They have propagated the observed fluxes and energy spectra of protons and alpha particles through a seasonally adjusted slab model of the polar atmosphere. The atmospheric ionization resulting from the slowing and stopping of protons and alpha particles is used to estimate an equilibrium vertical ionization profile which is then convolved with an absorption efficiency profile to yield a calculated absorption. There is good agreement between the computed and observed absorption when the daily averaged absorption is above 0.1 dB; this shows that the interplanetary ions are the dominant contributors on those days.

• OSTI ID: 5915564
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A4; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
ALPHA PARTICLES
BARYONS
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
EARTH ATMOSPHERE
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ENERGY SPECTRA
FERMIONS
GEOMAGNETIC FIELD
HADRONS
INTERPLANETARY MAGNETIC FIELDS
IONIZATION
IONOSPHERE
IONS
MAGNETIC FIELDS
MATHEMATICAL MODELS
NUCLEONS
PLANETARY IONOSPHERES
POLAR REGIONS
PROTONS
RADIATIONS
RADIOWAVE RADIATION
SOLAR ALPHA PARTICLES
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SPECTRA
STELLAR RADIATION