Frequency interpolation technique for broadband parabolic equation calculations

A method is developed for increasing the efficiency of broadband parabolic equation modeling. For broadband adiabatic mode calculations, the smoothnes s of the wavenumbers and mode functions in frequency permits interpolation across frequency. In order to permit frequency interpolation, the pressure field computed by the PE is transformed to mode space and the complex mode amplitudes are interpolated across frequency. For mildly range dependent en vironments a speed increase of a factor of ten can be achieved. A convergen ce test of propagation through internal waves indicates that a frequency in terpolation across four frequencies is possible.