PROJECT AURORA III. PART I: SOME EVIDENCE FOR THE OCCURRENCE OF HIGH ELECTRON DENSITIES IN THE AURORAL D AND E REGION. PART II: AN ANALYSIS OF THE STATISTICS OF SIMULTANEOUS AURORAL ECHOES.
Final rept., pts 1 and 2, 12 Feb 62-15 Jun 65,
CORNELL AERONAUTICAL LAB INC BUFFALO N Y
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Part I A-scope photographs of simultaneous auroral echoes at 49.7, 143.5 and 226 Mcs using scaled antenna systems with five degree beamwidths are presented and are discussed. The photographs clearly show that on occasion the 49.7 and 143.5 Mcs echoes can arise at disparate ranges. These photographs are interpreted as indicating the presence of local electron densities occupying regions which subtend angles smaller than the five degree system beamwidth in excess of 2 x 10,000,000 electronscu cm. Consequently single scatter theory cannot always be applied to the analysis of auroral echoes at frequencies as low as 50 Mcs. Part II The amplitude distribution and wavelength dependence of simultaneous auroral echoes at 49.7, 143.5 and 226 Mcs have been studied. Amplitude distributions are very closely Rayleigh distributed. The data are interpreted as indicating a wavelength dependence which varies as lambda to 3.5 power for frequencies between 50 Mcs and 143.5 Mcs and lambda to 6.5 power for frequencies between 143.5 and 226 Mcs. During conditions of strong auroral activity, auroral absorption may tend to mask the wavelength dependence at the two lower frequencies. Author