Measurement of Aspect Angle of Field-Aligned Plasma Irregularities in Mid-Latitude E Region Using VHF Atmospheric Radar Imaging and Interferometry Techniques

Remote Sensing

Jenn-Shyong Chen¹  Chien-Ya Wang²  Yen-Hsyang Chu³ 

[1] Center for General Education, China Medical University, Taichung 406040, Taiwan;Department of Optoelectric Physics, Chinese Culture University, Taipei 11114, Taiwan;Department of Space Science and Engineering, National Central University, Taoyuan 320317, Taiwan;

关键词: radar imaging;    aspect angle;    field-aligned plasma irregularities;    mid-latitude E region;    norm-constrained Capon;    VHF radar;   

DOI  :  10.3390/rs14030611

来源: DOAJ

【 摘 要 】

Multireceiver and multifrequency radar imaging were carried out with the 46.5 MHz MU radar in Japan (34.85°N and 136.10°E) to examine the aspect sensitivity of field-aligned plasma irregularities (FAIs) in the mid-latitude ionosphere E region. A radar beam was directed to geographic north and at 51° zenith angle, which was normal to the geomagnetic field line around 100 km height. Nineteen receivers and five carrier frequencies were used for radar imaging to retrieve the power distribution in the radar volume, and then the aspect angle along the geomagnetic field line was calculated according to the angular power distribution. Retrieval algorithms such as Fourier, Capon, and norm-constrained Capon (NC-Capon) were employed, in which the NC-Capon was applied to FAIs for the first time and found to be more suitable for the present study. The aspect angles estimated by the NC-Capon ranged between 0.1° and 0.4° mostly, and averaged around 0.2°, which were the same order to the previous measurements with radar interferometry (RI), made for equatorial electrojet irregularities and the lower mid-latitude sporadic E region. For comparison, RI-estimated aspect angles were also investigated and found to be close to that of NC-Capon, but distributed over a wider extent of angles.

【 授权许可】

Unknown