Variance and spectra of angle‐of‐arrival and Doppler fluctuations caused by ionospheric scintillation

The variance and spectra of angle‐of‐arrival and Doppler fluctuations were estimated by using 150‐ and 400‐MHz transmissions from the low‐orbiting U.S. Navy navigation satellites observed at the Millstone Hill radar facility. A theoretical model for the variance and spectra was also constructed by using the Rytov approximation and a power law power spectrum model for the electron density fluctuations. The model provided a means for the estimation of both the axial ratio and the location of the lower edge of the irregularity region, using only angle‐of‐arrival and Doppler observations made at a single location. Good agreement was obtained between the model estimates and observations. Analysis of data from two magnetic storms revealed simultaneous occurrences of E region and F region irregularities at invariant latitudes north of 56°.