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Comparison between in‐situ spectral measurements of F‐region irregularities and backscatter observations at 3 m wavelength
Author(s) -
Woodman R. F.,
Basu Sunanda
Publication year - 1978
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl005i010p00869
Subject(s) - backscatter (email) , scintillation , wavelength , physics , spectral index , spectral density , optics , ultra high frequency , magnetic field , computational physics , spectral line , astronomy , telecommunications , computer science , wireless , statistics , mathematics , quantum mechanics , detector
In situ measurements of equatorial electron density irregularities in the F‐region by rockets and satellites have yielded a power‐law form of one‐dimensional wave number spectrum of spectral index 2 in a direction transverse to the magnetic field over a scale size range of several km to several tens of m. Equatorial scintillation measurements in the WHF/UHF band which are most sensitive to irregularities of several km to several hundred m are consistent with the in situ spectral results. The backscatter measurements made at Jicamarca at 50 MHz provide an additional measurement of the spectral power at 3m wavelength. Computations are presented for the backscatter intensity expected from irregularities with power law spectrum in the transverse direction but which are infinitely elongated along the magnetic field. The computed intensity is compared with actual backscatter measurements and correlated scintillation observations. It is found that in order to reconcile the backscatter measurements with the simultaneous VHF/UHF scintillation observations a gaussian type cut‐off of the power‐law spectrum is necessary at m wavelengths near the O + ion gyro‐radius.