Split-step solution of the 4th moment equation for propagation through intense ionospheric disturbances

We solve the 4th moment equation for propagation through an extended random medium using the split-step technique. The statistics of ionospheric variations are specified in terms of a structure function consistent with Rino´s power law phase screen model (1979). Solutions of the 4th moment equation are not limited to the weak scatter or asymptotically strong scatter regimes; they are valid over the full range of geophysically observed conditions. We compare numerical results with observations of GPS (L band) scintillations acquired at Ascension Island (7.96°S, 14.41°W) during the previous solar maximum. We demonstrate that accurate predictions of the decorrelation time require proper treatment of the propagation geometry and rate at which the ray path scans through the drifting plasma irregularities.