PNNL-SA-32278

Written by: John W. Buck

Prepared for the U.S. Department of Energy

Pacific Northwest National Laboratory
Operated by the U.S. Department of Energy
By Battelle




Requirements for the MEPAS Atmospheric Transport Module

1.0 Introduction

This document describes the requirements for the Multimedia Environmental Pollutant Assessment System (MEPAS) Atmospheric Transport Module. This module is specifically designed as an object for inclusion in the Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES), which is a software platform that allows for the linking of various environmental modules into complete emission, transport, and exposure assessment systems (Whelan et al. 1997). These requirements can be used by software engineers and testers to ensure that this module functions properly. Test cases will be developed from the test plan to ensure that the product meets the needs of the clients and to establish a baseline version of the module.

2.0 Purpose of the MEPAS Atmospheric Transport Module

The purpose of the MEPAS Atmospheric Transport Module is to simulate the transport, dispersion, and deposition of chemical and radionuclide constituents that become airborne. Input to the module consists of 1) time-varying, contaminant mass fluxes to the atmosphere, 2) physical characteristics of the source area, 3) average annual site/regional climatological dispersion data, 4) site/regional topographical data, and 5) constituent properties. The emission information originates from a source term module and constituent properties originate from the Global Input Data (GID) file. All other inputs are entered through a Module User Interface (MUI). Output consists of regional patterns of time-varying, contaminant air concentrations (on an annual basis) near the earth's surface, and time-varying, deposition rates (on an annual basis) to earth's surface. The outputs may be endpoints for an analysis or be used as input to other modules.

3.0 Summary of Requirements for the MEPAS Atmospheric Transport Module

This section provides an overall summary of the requirements for the MEPAS Atmospheric Transport Module and associated pre and post processors, along with the specific requirements for the MUI. Detailed input, output, and scientific requirements are described in the sections that follow.

The MEPAS Atmospheric Transport Module will

4.0 Input Requirements for the MEPAS Atmospheric Transport Module

The MEPAS Atmospheric Transport Module has three sources of input to conduct calculations:

The specifications for the GID and AFF files are described in Whelan et al. (1997).

AFF Inputs. The AFF is a FRAMES data specification file that is defined as output from source modules and input to air modules. The AFF provides the MEPAS Atmospheric Transport Module with

GID File Inputs. The GID file is a FRAMES data specification file that contains all to contaminant property data for the entire set of modules linked under FRAMES. The GID file provides the MEPAS Atmospheric Transport Module with MUI Inputs. The MEPAS Atmospheric Transport Module MUI is divided into three main data groups: 1) climatology, 2) joint frequency distribution, and 3) topographical data. The MUI has the following general requirements:

The user needs to input the following data into the MUI (some are option depending on user selections):

Climatology Data

Joint Frequency Distribution Data - General Information

Joint Frequency Distribution Data - Occurrences of wind speed, wind direction by stability class (A-G)

Topographical Data

5.0 Output Requirements for the MEPAS Atmospheric Transport Module

The MEPAS Atmospheric Transport Module is required to output its results to an Atmospheric Transport Output (ATO) file. The ATO is a FRAMES Air Transport Module output file that is specified by the FRAMES data specifications (Whelan et al. 1997) and may be used as input to other modules. This module is also required to produce a listing file (*.ALS file) that documents the data actually read in by the model and provides a summary of intermediate calculation and simulation results.

The MEPAS Atmospheric Transport Module outputs the following data to the ATO file:

Other output files that the MEPAS atmospheric transport module is required to produce are the ALS and ERR File:

6.0 Scientific Requirements for the Atmospheric Transport Module

Mathematical formulations and assumptions for the MEPAS Atmospheric Transport Module are contained in Droppo and Buck (1996). Some of main computational functions of the model are

The MEPAS Atmospheric Transport Module will have the following scientific requirements:

The mathematical formulations documented in Droppo and Buck (1996) provide more detail on the requirements and design of the MEPAS Atmospheric Transport Module.

7.0 References

Droppo, J. G. and J. W. Buck. 1997. The Multimedia Environmental Pollutant Assessment System (MEPAS): Atmospheric Pathway Formulations. PNNL-11090, Pacific Northwest National Laboratory, Richland, Washington.

Whelan G., K. J. Castleton, J. W. Buck, G. M. Gelston, B. L. Hoopes, M. A. Pelton, D. L. Strenge, and R. N. Kickert. 1997. Concepts of a Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES). PNNL-11748, Pacific Northwest National Laboratory, Richland, Washington.