On the validity and comparison of various methods of analysis of ionospheric drift records for an equatorial station

Abstract

A few closely spaced receiver ionospheric drift records for an equatorial station in the Indian zone (Thumba, 0.6øS dip) are subjected to various methods of analysis proposed by different workers from time to time. It is shown that the modified time delay method of Bamgboye et al. offers a good substitute for the full correlation analysis for an equatorial station like Thumba when a complete knowledge of the ground diffraction pattern is to be derived from the time shifts alone. The methods proposed by POtter and Banerji are not applicable to an equatorial station owing to the extreme elongation of the irregularities in the magnetic north-south direction. The variant 2 method results for both V and V•. show a close correspondence with those of the full correlation analysis even for regions of extreme anisotropy like Thumba. The ionospheric drift records obtained by the closely spaced receiver technique are most commonly analyzed by the similar fades method [Mitra, 1949]. Pt•tter [1955] pointed out that in the absence of random velocities, the time shifts tx and tv are related by a straight line called Piitter's line. This, line enables the determination of the drift velocities from a smaller number of maximums and can be used even for an anisotropic pattern, which does not change its shape as it moves. Banertl [1960] modified this technique so that it could be used for a turbulent anisotropic pattern by using the results of Briggs and Spencer [1955] and making a suitable transformation of the coordinate system. This method requires a large number of time lags in order to get a good fit of the observed distribu-150 IOO SPEED IN M/S ß ß ß // ß ß e ß r;•.' //ß ß /e ß