Anomalous UV auroral spectra during a large magnetic disturbances

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

DOI:https://doi.org/10.1029/JA094iA06p06955· OSTI ID:5914460

Ishimoto, M; Meng, C I ^[1]; Romick, G R ^[2]; Huffman, R E ^[3]

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1. Johns Hopkins Univ., Laurel, MD (USA)
2. Univ. of Alaska, Fairbanks (USA)
3. Air Force Geophysics Lab., Hanscom Air Force Base, MA (USA)

Ultraviolet and far ultraviolet auroral spectra (1,100-2,900 {angstrom}) were taken during a very disturbed period (K{sub p} = 7+) on June 2, 1978, by the S3-4 polar-orbiting satellite over the nightside, winter southern hemisphere polar region. The spectra from the equatorward section ({minus}53{degree} to {minus}60{degree} geomagnetic latitude) of the auroral precipitation showed many striking differences from those of the diffuse aurora in other orbits or the poleward section of the diffuse auroral region ({minus}60{degree} to {minus}65{degree} geomagnetic latitude) on the same orbit. The differences are as follows: (1) intensity ratios of the nitrogen atomic lines (1,744 {angstrom} and 2,143 {angstrom}) to the Lyman-Birge-Hopfield (LBH) (3-10) band were 2 instead of 1; (2) intensity ratio of the oxygen line (1,356 {angstrom}) to the LBH (3-10) band was 15 instead of 4; (3) rotational temperature of the Vegard-Kaplan band system was 1,000 K instead of 400 K; and (4) effective vibrational temperature of the LBH band system was above 3,000 K instead of below 1,000 K. These and other characteristics are consistent with the assumption that observed spectra may originate from two different altitude regimes. Emissions from low altitudes (approximately 120 km) were produced by typical keV diffuse auroral-electron precipitation, and those from high altitudes (approximately 200 km) were produced by keV heavy particle precipitation. The lack of significant enhancement of Lyman {alpha} emission indicates a very weak proton precipitation. The authors believe that these low-latitude anomalous ultraviolet spectral features are likely due to the keV ion-atom oxygen precipitation, previously observed by a mass spectrometer at 800 km.

• OSTI ID: 5914460
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A6; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
AURORAL ZONES
CHARGED-PARTICLE PRECIPITATION
DATA ANALYSIS
DISTURBANCES
EARTH PLANET
ELECTROMAGNETIC RADIATION
ELEMENTS
FAR ULTRAVIOLET RADIATION
NITROGEN
NONMETALS
OXYGEN
PLANETS
POLAR REGIONS
RADIATIONS
SATELLITES
SOUTHERN HEMISPHERE
SPECTRA
ULTRAVIOLET RADIATION
ULTRAVIOLET SPECTRA