VHF backscatter radar observations of type I waves during a counter electrojet event

• Published in: Geophysical research letters Vol. 21; no. 18; pp. 2047 - 2050
• Main Authors: Somayajulu, V. V., Selvamurugan, R., Devasia, C. V., Cherian, Ligi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.09.1994; Blackwell Publishing Ltd
• Subjects: Backscattering; Dipping; Earth, ocean, space; Electric fields and currents; Electrojets; Electron density; Equatorial ionosphere; Exact sciences and technology; External geophysics; Geophysics; Ionosphere; Ionospheric irregularities; Ionospheric soundings; Phase velocity; Physics of the ionosphere; Plasma waves and instabilities; Radar; VHF; Ionospheric sounding; Magnetometry; Equatorial ionosphere; Radar; Density gradient; Electron density; Ionospheric irregularity; Counter electrojet
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/94GL01590

The paper presents simultaneous observations made at Trivandrum (Dip ‐ 0.5°N) during a strong counter electrojet event using VHF backscatter radar, Ionosonde and Magnetometer. The VHF backscatter radar observations of 2.7 m scale size irregularities have shown that Type I waves with phase velocities in the range of 180–220 ms−1 can be generated in the presence of a destabilizing gradient. This gives direct experimental evidence that the electron density gradient will affect the type I threshold velocity, sometimes substantially.