MEASUREMENTS OF GRADIENTS IN IONOSPHERIC PARAMETERS WITH A NEW 9-POSITION EXPERIMENT AT MILLSTONE-HILL

A new nine-position experiment is now routinely carried out with the Millstone Hill incoherent scatter radars which allows estimation of spatial gradients in the measured ionospheric scalar parameters N-e, T-e, and T-i, and in the components of the ion velocity vector vi. Use of this technique results in improved estimates of basic and derived parameters from incoherent scatter data at times of significant gradients. We detail the data analysis method and present the first results from this new experiment. The gradients in N,and in the components of vi are used to compute the motion term in the ionospheric F region continuity equation V.(Nv), which is then combined with partial derivative N/partial derivative t to estimate the O+ recombination rate beta at night. Meridional neutral winds U-mer are computed from the field-aligned ion velocity v(1) and a calculation of the O+ diffusion velocity v(d), and it is found that horizontal gradients in the ion velocity field at times significantly affect the calculation of the neutral winds.