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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/50461


    Title: 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
    Authors: Wang,CY;Chu,YH;Su,CL;Kuong,RM;Chen,HC;Yang,KF
    Contributors: 太空科學研究所
    Keywords: QUASI-PERIODIC ECHOES;EQUATORIAL ELECTROJET;INTERFEROMETRY INVESTIGATIONS;TURBULENCE;WAVES
    Date: 2011
    Issue Date: 2012-03-27 17:32:34 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 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 degrees 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.
    Relation: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
    Appears in Collections:[太空科學研究所 ] 期刊論文

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