Abstract
<strong class="journal-contentHeaderColor">Abstract.</strong> The EISCAT UHF radar system was used to study the characteristics of E-region coherent backscatter at very large magnetic aspect angles (5â11°). Data taken using 60 μs pulses during elevation scans through horizontally uniform backscatter permitted the use of inversion techniques to determine height profiles of the scattering layer. The layer was always singly peaked, with a mean height of 104 km, and mean thickness (full width at half maximum) of 10 km, both independent of aspect angle. Aspect sensitivities were also estimated, with the Sodankylä-Tromsø link observing 5 dB/degree at aspect angles near 5°, decreasing to 3 dB/degree at 10° aspect angle. Observed coherent phase velocities from all three stations were found to be roughly consistent with LOS measurements of a common E-region phase velocity vector. The E-region phase velocity had the same orientation as the F-region ion drift velocity, but was approximately 50% smaller in magnitude. Spectra were narrow with skewness of about +1 (for negative velocities), increasing slightly with aspect angle.
Highlights
It is well known that coherent radar backscatter is obtained from the auroral E-region
Coherent backscatter can be observed at aspect angles greater than 2°, in contradiction to the predictions of linear theory
In these experiments coherent backscatter at 933 Mhz has been observed at aspect angles up to 11°, at which point the observed echo strengths are at approximately the same level as incoherent backscatter
Summary
It is well known that coherent radar backscatter is obtained from the auroral E-region. A series of previous experiments (Moorcroft and Schlegel, 1988, 1990; Schlegel and Moorcroft, 1989; Schlegel et al, 1990) have demonstrated the utility of the EISCAT UHF system for making detailed observations of coherent backscatter from the auroral E-region. In this study we shall report on the results of a June 1989 experiment, which detected coherent echoes at aspect angles as large as 11.3°. These data have been used to retrieve height profiles of the scattering region, to determine the aspect sensitivity over a wide range of aspect angles, and to examine the relationship between F-region electric fields and coherent phase velocities
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
