Analysis of Observations of Interplanetary Scintillations

It is shown that under suitable conditions it may be possible to derive the speed of the solar wind from observations of interplanetary scintillations taken with a single antenna. Theory suggests that the characteristic diffraction pattern of the interplanetary medium may he identified as a sequence of minima in a Bessel transform of the time autocorrelation function of the observed (weak) variations in intensity; the location of the minima gives the speed of the solar wind. The necessary analysis has been done on scintillation data of CTA 21 taken at 430 MHz. On two occasions, out of eight analyzed, a pattern of deep minima was observed in the Bessel transform. In addition, power spectra of the observed intensity were obtained on all eight occasions, and a number of these spectra could be represented by a power law. It is suggested that the power-law frequency spectra may be interpreted in terms of a power4aw wavenumber spectrum of irregularities in electron density in the solar wind.