Mid-latitude E region field-aligned irregularities observed with the MU radar

Journal Article · Sun Sep 01 00:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA01321· OSTI ID:5180620

Yamamoto, Mamoru; Fukao, Shoichiro; Tsuda, Toshitaka; Kato, Susumu ^[1]; Woodman, R F ^[2]; Ogawa, Tadahiko ^[3]

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1. Kyoto Univ. (Japan)
2. Inst. Geofisico del Peru, Lima (Peru)
3. Communications Research Lab., Ibaraki (Japan)

Fine structures of E region field-aligned irregularities were observed on June 24-25, 1989, with the MU radar at Shigaraki, Japan. Doppler spectra were obtained every 20 s with a range resolution of 600 m. Field-perpendicular echoes appeared from 2130 to 2330 LT and from 0400 to 1100 LT, times that correspond to postsunset and postsunrise period in the E region. A preliminary examination of the Doppler spectra indicates spectral widths of 50-120 m s{sup {minus}1} and the mean Doppler velocities are well below the ion acoustic speed. These spectral characteristics are consistent with those obtained in the equatorial and auroral electrojets, and have been attributed to the gradient drift instability. The echoes observed during the postsunset and postsunrise periods showed quite different morphologies in the time-height distribution. For this reason, they are classified into two types, continuous and quasi-periodic. The appearance of the continuous echoes was mainly continuous in time and situated between 90 and 100 km altitude during the postsunrise period. The appearance of the quasi-periodic echoes was intermittent with periods of 5-10 min and situated above 100 km altitude during the postsunset period. The quasi-periodic echoes showed phase propagation toward the radar, while the averaged mean Doppler velocity was away from the radar. By measuring the time delays in echo regions from five directions, an apparent westward motion (approximately 120 m s{sup {minus}1}) of the irregularity regions was estimated.

• OSTI ID: 5180620
• Journal Information: Journal of Geophysical Research; (United States), Vol. 96:A9; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
E REGION
ELECTRON DENSITY
AURORAL ZONES
DOPPLER EFFECT
DRIFT INSTABILITY
ELECTROJETS
EQUATOR
MORPHOLOGY
RADAR
VELOCITY
CURRENTS
EARTH ATMOSPHERE
ELECTRIC CURRENTS
INSTABILITY
IONOSPHERE
MEASURING INSTRUMENTS
PLANETARY IONOSPHERES
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
RANGE FINDERS
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena