Application of the Calder Finite Difference Diffusion Model to Calculations of Instantaneous Elevated Line Source Dosages.
DUGWAY PROVING GROUND UTAH
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This paper compares calculations of vertical and surface dosage distributions, obtained from a finite difference numerical solution of the classical line source diffusion equation, to calculations obtained from an analytical solution and to observed distributions obtained from several line source releases. The analytical solution uses constant values of vertical turbulence and wind speed averaged with height. This solution then approximates the effects on surface dosages of increasing stability aloft by using reflection from the top of the mixing layer. The finite difference numerical solutions considers the change of eddy diffusivity and wind speed with height in such a way as to produce vertical dosage profile closer to the observed. Turbulence values for use in the numerical model are obtained from calculations of vertical diffusivity based on statistical theory. The numerical solution predicts the vertical dosage profile more accurately than the analytical solution. Both solutions predict surface dosages equally well. Verification of the numerical solution on other data appears desirable.
- Atmospheric Physics