Discussion of paper by F. L. Scarf, ‘Effect of coherent density fluctuations on the radar determination of total electron content’

Abstract

Howard et al. [1965] and Yoh et al. [1966] have recently reported on a beautiful set of radar experiments in which group and phase delay introduced by the cislunar medium were interpreted in terms of a mean plasma electron concentration. Electron concentrations found by these techniques appear to be very much higher than those derived by other means, such as from whistlers [Carpenter, 1966], from micropulsations [Watanabe, 1965], or on theoretical grounds [Dessler and Michel, 1966]. Scarf [1966] subsequently attempted to explain the discrepancy as an effect of coherent density fluctuation on the mean propagation constants of the plasma, In what follows we show that the effect discussed by Scarf is probably unimportant and hence that some other explanation of the curious discrepancy between the results of the radar propagation experiments and the currently accepted model of the magnetospheric tail must be sought.