Statistical investigations of layer-type and clump-type plasma structures of 3-m field-aligned irregularities in nighttime sporadic e region made with Chung-Li VHF radar

C. Y. Wang, Y. H. Chu, C. L. Su, R. M. Kuong, H. C. Chen, K. F. Yang

研究成果: 雜誌貢獻期刊論文同行評審

15 引文 斯高帕斯(Scopus)

摘要

With interferometry measurements made with Chung-Li 52 MHz VHF radar, characteristics of layer-type and clump-type plasma structures of 3-m field-aligned irregularities are investigated for the first time. Long-term statistics show that the thickness and the zonal extent of the layer-type plasma structures are in the ranges of approximately 0.1-4 km and 5-28 km, respectively. However, the vertical and zonal extents of the clump-type plasma structure are comparable with each other, ranging from 2 to 12 km. These features clearly imply that the cross sections of the layer-type and clump-type plasma structures intercepted by a fan-like effective radar beam are, respectively, in highly elongated and nearly circular shapes. The mean height of the clump-type plasma structures is slightly higher than that of the layer-type plasma structures by about 5 km. From interferometry-measured echo distributions about the perpendicularity to the local magnetic field line, it is found that the mean aspect angle of the 3-m field-aligned irregularities for the layer-type plasma structures is about 0.05° smaller than that for the clump-type plasma structures. In addition, the height dependence of the aspect angle of the layer-type plasma structures is different from that of the clump-type plasma structures. The former tends to increase with height, while the later decreases with altitude. The zonal trace velocities of the layer-type and clump-type plasma structures estimated from their temporal displacements in the horizontal plane are, respectively, in ranges of-150-100 m/s and-180-80 m/s, in which negative (positive) values indicate eastward (westward) drift. The characteristics of the Doppler spectra of the echoes from the layer-type and clump-type plasma structures are also analyzed and the relations between the spectral parameters and the aspect angles are also discussed in this article.

原文???core.languages.en_GB???
文章編號A12311
期刊Journal of Geophysical Research: Space Physics
116
發行號12
DOIs
出版狀態已出版 - 2011

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