E-REGION MIDLATITUDE DECAMETER IRREGULARITIES OBSERVED AT 4 RADAR FREQUENCIES - EXPERIMENT AND FIRST RESULTS

Citation
Gc. Hussey et al., E-REGION MIDLATITUDE DECAMETER IRREGULARITIES OBSERVED AT 4 RADAR FREQUENCIES - EXPERIMENT AND FIRST RESULTS, Annales geophysicae, 15(7), 1997, pp. 918-924
Citations number
13
Categorie Soggetti
Astronomy & Astrophysics","Geosciences, Interdisciplinary","Metereology & Atmospheric Sciences
Journal title
ISSN journal
09927689
Volume
15
Issue
7
Year of publication
1997
Pages
918 - 924
Database
ISI
SICI code
0992-7689(1997)15:7<918:EMDIOA>2.0.ZU;2-2
Abstract
In this paper an experiment designed for multifrequency azimuthal Dopp ler-spectrum investigations of decametre-scale plasma irregularities i n the midlatitude E region is introduced and some preliminary results are presented. The observations were made with the high-frequency Vale nsole radar in the south of France. The radar operated in a multifrequ ency mode that allowed simultaneous measurements of Doppler spectra at the four frequencies of 9.23, 11.03, 12.71 and 16.09 MHz, which corre spond to scatter from field-aligned irregularities with wavelengths of 16.2, 13.6, 11.8 and 9.3 m, respectively. In addition, a digital iono sonde was operating beneath a small part of the radar viewing region. The data show that lower-frequency echoes are stronger, more frequent and more spatially extended than higher-frequency ones, in general agr eement with theory and rocket measurements. On the other hand, the pre liminary analysis shows no pronounced differences of the Doppler spect rum with radar frequency. Some trends in the spectral moments do exist , however, which can be understood as the result of temporal and/or sp atial mixing of backscatter from directly generated (primary) plasma w aves by the gradient drift instability and secondary low-velocity wave s. Finally, a close relation of mid-latitude coherent backscatter with patchy sporadic E-layers is present in the data, but the details of t his relation remain unresolved.