Relative Intensity of Incoherent and Semicoherent Scattering from Turbulent Particulate Clouds.
Topical rept. 21 Nov 77-31 Jul 78,
SRI INTERNATIONAL MENLO PARK CA
Pagination or Media Count:
Recently, interest has revived in the nature of radar backscatter from dust clouds lofted by surface nuclear detonations. As a result, radar backscatter experiments are being performed on high-explosive-produced dust clouds. Traditionally, the measurements obtained are interpreted as being the result of incoherent addition of scattering from the individual dust particles. However, during their early stages of evolution, such clouds demonstrate intense turbulence with apparent abrupt transitions from clean to dirty air. Such an environment seems conductive to contributions from semicoherent scattering. If such coherent contributions are important, then data interpretation must consider this process. This document presents analytical scattering formulas to be used to compare the magnitude of the two scattering processes, incoherent and semicoherent. A plausible model of the in-situ, three-dimensional spatial frequency power spectrum of dielectric fluctuations in the dustair interface is presented, and an analytical model of the dust-particle size distribution is derived--based loosely on the sketchy field measurement data available to us. Finally, all of the pieces of our analytical formalisms are assembled. The results show that the semicoherent scattering contribution to radar backscattering from high-explosive-produced dust clouds is very likely significantly weaker than contributions from incoherent scattering. We conclude that interpretation of radar backscatter data--for example, that of the Misers Bluff radar experiments--need not consider coherent scattering processes. Author
- Active and Passive Radar Detection and Equipment