Turbulence in planetary occultations: A strong scattering formulation including an inhomogeneous background
Article first published online: 7 DEC 2012
Copyright 1982 by the American Geophysical Union.
Volume 17, Issue 3, pages 565–573, May-June 1982
How to Cite
1982), Turbulence in planetary occultations: A strong scattering formulation including an inhomogeneous background, Radio Sci., 17(3), 565–573, doi:10.1029/RS017i003p00565.(
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 18 JAN 1982
- Manuscript Received: 8 OCT 1981
We show, from a Huygens-Fresnel integral formulation of the scattered electromagnetic field, that the wave equation for a thin turbulent medium with nonconstant mean characteristics can be reformulated as a problem involving turbulence on a constant background. This is accomplished by a set of simultaneous transformations, which, when reversed and applied to known solutions of the simpler problem involving a constant background, yield results that correctly account for the inhomogeneous ambient atmosphere upon which the turbulence is superimposed. When applied to the mutual coherence function it is found that this quantity is unaltered if the separation of the two field points in the plane of the receiver is replaced by the corresponding separation obtained by projecting these points along the average refracted rays back to the ray periapsis. For the associated spectral broadening function this implies that spectra corresponding to different occultation depths and geometries may be obtained by simple translation of a shape-invariant spectrum along the frequency axis. We also find that the scintillation index approaches asymptotically unity in strong scattering in precisely the same way as if the ambient background were strictly homogeneous, consistent with recent numerical simulations of a one-dimensional scattering model.