  Numerical solutions are given for a parabolic approximation of the acoustic
wave equation at 200 and 250 Hz in two and three spatial dimensions to
determine if azimuthal coupling in the cross-range coordinate significantly
affects horizontal correlation in the presence of internal gravity waves in the
sea. No evidence for coupling is found for distances of 4000 km and less. This
implies that accurate solutions are possible using computations from uncoupled
vertical slices. Shapes of horizontal correlation are closer to shapes given by
two theories than at lower frequencies.
