Comparisons between strong HF backscatter and VHF radar aurora
Article first published online: 7 DEC 2012
Copyright 1979 by the American Geophysical Union.
Volume 14, Issue 6, pages 1121–1133, November-December 1979
How to Cite
1979), Comparisons between strong HF backscatter and VHF radar aurora, Radio Sci., 14(6), 1121–1133, doi:10.1029/RS014i006p01121., , and (
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Received: 8 JAN 1979
It is well known that various types of irregularity structures exist in the E and F regions of the auroral and subauroral ionosphere. In this study the location and occurrence probability of these structures have been compared with HF and VHF radars located in Finland and Germany. It has been found that E-region radar aurora is observed at both HF and VHF frequencies and that its cross section approximately follows a λ3 law in this frequency range. The F-region irregularities and the backscatter echoes caused by them are found to fall into auroral and nonauroral groups. The auroral group occurs near the L values of radar aurora and is often observed on the same magnetic field unes as the equatorward portion of the VHF radar aurora. Moreover, there is a second type of F-region echo that appears to be anticorrelated with radar auroral activity. This latter type of F-region echo occurs at lower latitudes (L value between 3 and 4) and appears to require low electron densities in the F region. HF and VHF radar auroras are known to be produced by electrostatic plasma streaming instabilities. The sources of F-region HF backscatter are not as yet known; however, they may be due to either irregular structures in particle precipitation or to plasma instability mechanisms.