Conjugacy of daytime ELF-VLF emission activities in the auroral zones

Journal Article · Fri Jun 01 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA095iA06p07847· OSTI ID:5311214

Sato, Natsuo ^[1]; Suzuki, Hiroyuki; Maezawa, Kiyoshi ^[2]; Saemundsson, T ^[3]

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1. National Institute of Polar Research, Tokyo (Japan)
2. Yamagata Univ. (Japan)
3. Univ. of Iceland, Reykjavik (Iceland)

Statistical characteristics of emission occurrence are examined, using 1 year of digital data of 750-Hz, 2-kHz, and 4-kHz intensity records. These waves were measured simultaneously at a conjugate pair of stations, namely Syowa Station in Antarctica and Husafell in Iceland. The following notable diurnal and seasonal variation and Kp dependence was found for the daytime emissions (04-14 MLT): (1) The 750-Hz emissions were mostly observed during the daytime around noon in both conjugate regions. The emission occurrence reached a maximum 1-3 hours earlier at Syowa than at Husafell during the equinox season. The seasonal variation of 750-Hz emission occurrence showed a maximum during local summer and a minimum during local winter at both stations. The ratio of the emission enhancement in summer to that at the equinox is higher at Husafell than at Syowa. The emissions mostly occurred during moderately disturbed conditions of Kp {approximately} 2-4 at both stations. (2) The 2-kHz emission occurrence reached a maximum around 13 MLT at Syowa and around 11 MLT at Husafell. Peaks of the emission occurrence during summer shifted to the afternoonside at Syowa and to the morningside at Husafell. The occurrences at Syowa reached a maximum during local summer and a minimum during winter. (3) The occurrence of 4-kHz emissions was much more frequent at Husafell than at Syowa. The emissions at Husafell occurred mostly in the morning ({approximately}08 MLT) and in local winter, and the occurrences became more frequent with increasing magnetic activity. On the bases of these statistical characteristics, the authors discuss the effects of sunlight and geomagnetic activity which cause an asymmetry of wave propagation from the magnetosphere to the ionosphere in the two hemispheres.

• OSTI ID: 5311214
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 95: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
ASYMMETRY
AURORAL HISS
AURORAL ZONES
DAILY VARIATIONS
DATA ANALYSIS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTROMAGNETIC RADIATION
IONOSPHERE
MAGNETIC STORMS
MATHEMATICS
PLANETARY IONOSPHERES
RADIATIONS
SEASONAL VARIATIONS
STATISTICS
VARIATIONS
WAVE PROPAGATION