An asymptotic method of modeling radio occultations

A short-wave asymptotic method of modeling radio signals registered during radio occultation experiments is discussed. The method uses the theory of Fourier integral operators. Use of this method allows for a faster simulation of radio occultation data as compared to the method of multiple phase screens. The method was tested using global fields from analyses of the European Centre for Medium-Range Weather Forecast. The comparison of the asymptotic solution with the multiple phase screen method shows their good agreement. The limits of the applicability of the new method are discussed. (C) 2003 Elsevier Ltd. All rights reserved.