1. NAME AND TITLE

DWNWND: Interactive Gaussian Plume Atmospheric Transport Model.

2. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; PDP-10.

4. NATURE OF PROBLEM SOLVED

DWNWND computes sector center-line and average pollutant concentrations for sites downwind of the source. The code is interactive and prompts the user to input source and atmospheric parameters. Horizontal and vertical diffusivities are computed based on the user's choice of dispersion parameters. Eight sets of dispersion parameters are available. Plume tilt and plume depletion are among the mechanisms considered.

5. METHOD OF SOLUTION

DWNWND is an interactive implementation of the Gaussian plume formulation of atmospheric transport. Lagrangian interpolation is used to compute equation coefficients based on surface roughness if the user's choice is Hosker's formulation of the Briggs-Smith parameters. A Simpson's Rule integration is used to calculate plume depletion.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

DWNWND executes a typical problem run in approximately 1 second.

8. COMPUTER HARDWARE REQUIREMENTS

DWNWND is operable on the PDP-10 computer. No auxiliary storage is required.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCE

D. E. Fields and C. W. Miller, "User's Manual for DWNWND An Interactive Gaussian Plume Atmospheric Transport Model with Eight Dispersion Parameter Options," ORNL/TM-6874 (May 1980).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code.

12. DATE OF ABSTRACT

February 1982; revised February 1983.