angeo-16-55-1998.pdf (1.48 MB)
Simultaneous observations at different altitudes of ionospheric backscatter in the eastward electrojet
journal contribution
posted on 2015-03-18, 11:49 authored by Stephen E. Milan, Mark LesterA common feature of evening near-range ionospheric backscatter in the CUTLASS Iceland radar field of view is two parallel, approximately L-shell-aligned regions of westward flow which are attributed to irregularities in the auroral eastward electrojet region of the ionosphere. These backscatter channels are separated by approximately 100–200 km in range. The orientation of the CUTLASS Iceland radar beams and the zonally aligned nature of the flow allows an approximate determination of flow angle to be made without the necessity of bistatic measurements. The two flow channels have different azimuthal variations in flow velocity and spectral width. The nearer of the two regions has two distinct spectral signatures. The eastern beams detect spectra with velocities which saturate at or near the ion-acoustic speed, and have low spectral widths (less than 100 m s–1), while the western beams detect lower velocities and higher spectral widths (above 200 m s–1). The more distant of the two channels has only one spectral signature with velocities above the ion-acoustic speed and high spectral widths. The spectral characteristics of the backscatter are consistent with E-region scatter in the nearer channel and upper-E-region or F-region scatter in the further channel. Temporal variations in the characteristics of both channels support current theories of E-region turbulent heating and previous observations of velocity-dependent backscatter cross-section. In future, observations of this nature will provide a powerful tool for the investigation of simultaneous E- and F-region irregularity generation under similar (nearly co-located or magnetically conjugate) electric field conditions.
Funding
CUTLASS is supported by PPARC, the Swedish Institute for Space Physics, Uppsala, and the Finnish Meteorological Institute. SEM is supported on PPARC grant no. GR/L00865.
History
Citation
ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, 1998, 16 (1), pp. 55-68 (14)Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and AstronomyVersion
- VoR (Version of Record)
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ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCESPublisher
European Geosciences Union (EGU), Copernicus Publications, Springer Verlag (Germany)issn
0992-7689eissn
1432-0576Copyright date
1998Available date
2015-03-18Publisher DOI
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http://www.ann-geophys.net/16/55/1998/angeo-16-55-1998.htmlLanguage
enAdministrator link
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Science & TechnologyPhysical SciencesAstronomy & AstrophysicsGeosciences, MultidisciplinaryMeteorology & Atmospheric SciencesGeologyauroral ionosphereionospheric irregularitiesplasma convectionRADAR AURORAL BACKSCATTERSMALL-SCALE IRREGULARITIESLATITUDE F-REGIONEQUATORIAL ELECTROJETDOPPLER VELOCITYPLASMA-WAVESDRIFTCONVECTIONDYNAMICSMOTIONS
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