Line-of-sight Doppler velocity V∗ and three-dimensional apparent echolocation (XL, YL, ZL), are among the principal parameters available for each ionospheric echo from most observing modes of the dynasonde. An ensemble of three or more echoes containing diverse XL, YL, ZL is sufficient to determine the full vector velocity VX, VY, VZ common to the ensemble. We present a procedure based on weighted least-squares, which may be applied to an entire recording or to suitably selected parts of it, to yield ‘best’ estimates of VX, VY, VZ and their confidence limits. Each observation is weighted according to an r.m.s. phase error incurred in the estimation of XL, YL, ZL and V∗. A measure of the fraction of observed Doppler variance expressed by the analysis is useful to decide if spatial or temporal variabilities are significant within the ensemble. Often at Tromsø the results are directly applicable to the estimation of prevailing electric fields with high (⪢10 s) time resolution.

A computer is used to simulate fading records that might have been observed in a spaced-antenna drift experiment. The model for computer analysis permits scattering centers to be located at random positions, then moved stepwise across the sky to simulate a drift; random changes are also studied. The output format matches that of actual experimental equipment, and the simulated records are used to validate standard correlation analysis programs. Correlation analysis correctly detects the mean direction and speed of the ‘diffraction’ pattern produced in this way, and estimates a random velocity fluctuation magnitude directly related to the random changes in the model. The statistically rigorous formulation of correlation analysis by Fedor (1967) is shown to estimate reasonable error limits for the wanted parameters.

Dynamic processes in the E-region, resulting mainly in neutral air motions, appear as the direct causes of certain phenomena (e.g. sporadic E) and are also responsible for much of the less obvious variability of the region. Since it is the time variation of the vertical structure which is usually observed, and since the vertical ionization gradients are large, vertical motions are of greatest interest. We show here that the vertical component of motion of the neutral air, although of relatively small magnitude, cannot be neglected in estimating vertical ion motions. It is therefore important that the total motion of the air, and of the ionization, be subject to measurement.