Ionospheric wind measurements at 150 KC

The results of ionospheric wind measurements utilizing the three spaced-receiver technique at longwave lengths are given. Evidence is presented which indicates the presence of diurnal and seasonal variations of upper atmosphere wind movements. The measured wind magnitudes range from 20 to 300 meters per second with most probable values between 40 and 100 meters per second. By the method of Briggs-Phillips (1950), the "angular spreading" of the downcoming reflected wave is found to be approximately as compared to the theoretical prediction of . This appears to verify the fact that the ionosphere acts as a diffracting screen at long wavelengths. The calculated rms line-of-sight speeds of ionospheric scattering centers are found to be about 6-8 meters per second. Agreement is found between the speeds obtained by the Booker-Ratcliffe-Shinn (1950) autocorrelation method and Ratcliffe\´s (1958) speed of fading method. A study of the fading rate of the first reflected echo indicates the presence of fades of 1/4 to 15 minutes duration with maximum between 1 and 2 minutes. The fading rate is found to increase with greater indices of geomagnetic activity (kw). Several other factors and correlations are also discussed.