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A Search by Radar Backscatter, for Irregularities Produced by the Lagopedo F-Region Electron Depletion Releases.

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Final rept. 1 Jun-31 Dec 77,

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During early September 1977, the Los Alamos Scientific Laboratory launched two rockets bearing the explosive nitromethane into the F-region over Kauai in the Hawaiian Island chain. The detonation of this material produced a large, generally spherically shaped, reduction in the F-region electron density centered at altitudes between 265 and 285 km. The experiment was called Operation Lagopedo. Some plasma theoreticians had expected that the edges of this electron-depleted region would become unstable by the gradient drift instability process, leading to the generation of magnetic-field-aligned irregularities similar to those produced in the equatorial ionosphere. The naturally produced equatorial irregularities, called spread-F, are regularly detected by magnetic-field-aligned backscatter radar echoes at HF. Therefore, an attempt was made by SRI International to detect the presence of irregularities in the Lagopedo ionospheric hole by the same HF backscatter means. This report describes the SRI experimental program. The SRI HF radar was capable of detecting field-aligned irregularities with spatial wavelengths between approximately 5 and 10 m 16 MHz to 32 MHz radar frequencies. System sensitivity was a factor of 200 to 800 times more sensitive than equatorial equipment used at comparable frequencies. An additional 20 dB of Doppler processing can be achieved during post-mission data reduction if necessary. The magnetic orthogonality condition was met in the vicinity of the Lagopedo electron depletion regions, yet no field-aligned echoes were observed.

Subject Categories:

  • Atmospheric Physics
  • Active and Passive Radar Detection and Equipment
  • Plasma Physics and Magnetohydrodynamics

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