1. NAME AND TITLE

MESOI: Interactive Mesoscale Lagrangian Puff Dispersion Model with Deposition and Decay.

2. CONTRIBUTORS

Pacific Northwest Laboratory, Richland, Washington.

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran 77; VAX 11/780.

4. NATURE OF PROBLEM SOLVED

MESOI Version 2.0 is a third generation Lagrangian puff transport and diffusion model based on the earlier MESODIF model. It explicitly treats physical processes affecting material released to the atmosphere which were not treated in the earlier versions. It is an interactive model for estimating the transport, diffusion, deposition and decay of effluents released to the atmosphere. It is capable of treating simultaneous releases from as many as four release points which may be elevated or at ground level.

5. METHOD OF SOLUTION

The puffs are advected by a horizontal wind field that is defined in three dimensions. The wind field may be adjusted for expected topographic effects. The concentration distribution within the puffs is initially assumed to be Gaussian in the horizontal and vertical. However, the vertical concentration distribution is modified by assuming reflection at the ground and the top of the atmospheric mixing layer. Material is deposited on the surface using a source depletion, dry deposition model and a washout coefficient model. The model also treats the decay of a primary effluent species and the ingrowth and decay of a single daughter species using a first order decay process.

6. RESTRICTIONS OR LIMITATIONS

No change or group of changes that cause the model execution time to exceed 15 minutes will be retained. Model execution time for simulation of a 12 hour release from a single source is less than 5 minutes.

7. TYPICAL RUNNING TIME

No study has been made by RSIC of typical running times for MESOI Version 2.0.

8. COMPUTER HARDWARE REQUIREMENTS

Early versions of MESOI were designed for computers with relatively limited memories. This version is targeted for minicomputers with relatively large memories such as the VAX and the Data General MV 8000 computers. It is highly modular, however, so it can be fitted into smaller minicomputers or larger microcomputers.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran 77 compiler is required.

10. REFERENCE

J. V. Ramsdell, G. F. Athey, C. S. Glantz, "MESOI Version 2.0: An Interactive Mesoscale Lagrangian Puff Dispersion Model With Deposition and Decay," NUREG/CR-3344 (November 1983).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code, sample problem, and meteorological data input.

12. DATE OF ABSTRACT

June 1986.