User Assessment of 

Smoke-Dispersion Models 

for Wildland Biomass 

Burning 

Steve Breyfogle and Sue A. Ferguson 
Authors STEVE BREYFOGLE is a consultant, J.O.T. Consulting, P.O. Box 358, Roslyn, WA 

 98941; and SUE A. FERGUSON is an atmospheric scientist, U.S. Department of 

 Agriculture, Forest Service, Pacific Northwest Research Station, Forestry Sciences 

 Laboratory, 4043 Roosevelt Way, Seattle, WA 98105-6497.

Breyfogle, Steve; Ferguson, Sue A. 1996. User assessment of smoke-dispersion 

models for wildland biomass burning. Gen. Tech. Rep. PNW-GTR-379. Portland, 

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 30 p. 

Several smoke-dispersion models, which currently are available for modeling smoke 

from biomass burns, were evaluated for ease of use, availability of input data, and 

output data format. The input and output components of all models are listed, and differences in model physics are discussed. Each model was installed and run on a personal computer with a simple-case example. The steps required to obtain meaningful 

output for each model are described. Because validation data for wildland biomass 

burns were unavailable at the time of this assessment, recommending the use of one 

model over another was not possible. Limiting features of the source-strength component available for each model, however, suggest that dispersion models will not validate properly until models of source strength in biomass burns improve. Without validation data, preliminary recommendations are based on the style of user, user interfaces, output format, and available model components. Suggestions are made for 

which model that a local project, regional project, regional systems manager, or research scientist might select for research, regulatory, planning, and screening 

purposes. 

Keywords: Smoke, dispersion, models, fire, prescribed fire, emissions.

Abstract
Smoke-dispersion models are becoming increasingly valuable tools in smoke management, especially for screening and planning. Unfortunately, modeling smoke emission, 

transport, and dispersion from wildland biomass burns is not easy. The areal extent and 

varied species of biomass fuels require coarse estimates and empirical calculations to 

determine rates of source heat and emission. In addition, many wildland biomass burns 

originate in complex terrain, which influences transport winds and mixing heights. This is 

an especially important concern for nonbuoyant or neutrally buoyant plumes that are 

common in smoldering fires and understory burns. 

Modeling emissions from industrial stacks, on the other hand, is much more precise 

because source heat and emissions can be exactly known. Also, stack emissions usually 

are well above or away from influencing terrain and rarely go into a smoldering phase. 

Therefore, although many components of biomass smoke modeling can be borrowed 

from industrial stack models, source-strength and smoldering trajectories are unique to 

wildland biomass burning. 

Figure 1 shows the basic elements of smoke modeling. To determine source strength, 

components of heat and fuel (particle and gas species composition) must be known. For 

simulating biomass burns, additional information is required on (1) the pattern of ignition, 

(2)fuel moisture by size, (3) fuel loading by size, (4) fuel distribution, and (5) local weather 

that influences burn rates. Heat-release and emission rates for each gas species and 

particle size, which are calculated from the source-strength component, go into the 

plume-rise calculations. To accurately model plume-rise, ambient conditions of the 

atmosphere (temperature, wind, and humidity) and its mixing height must be known. In 

biomass burning, information on the existence and extent of local valley inversions also 

may be required. Once the height of the plume has been calculated, its horizontal 

trajectory and dispersion may be determined. In many industrial stack plumes and intense 

biomass fires, the trajectory winds can be well above influencing terrain, and standard 

dispersion algorithms are adequate. For low-intensity biomass fires, however, trajectory 

winds often are near Earth's surface, follow slope undulations, and are affected by diurnal 

temperature and pressure changes. The desired result of all models is the ability to 

estimate particle and gas concentrations, which affect human health and alter visibility. 

Several models have been adapted or specifically designed to accommodate the 

peculiarities of wildland biomass burning. The primary difference between dispersion 

models for biomass burns and those for point-source (industrial-stack) dispersion models 

is the ability to accept data and calculate plume rise from a buoyant source of areal 

emissions associated with burning biomass fuels. The following dispersion models 

currently are used by Federal wildland managers and were available for this 

assessment: SASEM (Sestak and Riebau 1988), VALBOX (Sestak and others 1989), 

VSMOKE (Lavdas, in press), VSMOKE-GIS,1

 NFSpuff (Harrison 1995), TSARS Plus 

(Hummel and Rafsnider 1995), and CALPUFF (Scire and others 1995b). 

1 VSMOKE and VSMOKE-GIS are scientifically the same, but the input 

and output formats are different (Personal communication. 1994. William 

A. Jackson, air resource specialist, U.S. Department of Agriculture, 

Forest Service, National Forests in North Carolina, United States Federal 

Courthouse Building, P.O. Box 2750, Asheville, NC 28802). The 

distinction may become apparent as the merits of each are discussed in 

the following sections. 

1 

Introduction 
2 
3

One reason for conducting this assessment is to help determine if the current direction 

in biomass smoke modeling is appropriate and what, if any, additional work is required 

to make the models more useful for smoke management. We, therefore, assessed the 

available models by evaluating their components in relation to the types of users and 

possible wildland smoke applications. In addition, each model was set up and run on a 

personal computer (PC) with a simple-case example to evaluate the ease with which 

meaningful output could be obtained. The following sections describe principle results, 

and the appendix summarizes the software capabilities of each model. 

This qualitative review makes no attempt to validate smoke-dispersion models for biomass burning. Recommendations for model usage and future research are based only 

on subjective assessments of model performance. 

In wildland fire management, prescribed burning carries the major emphasis for 

normal model use. Many users screen burns with models to help estimate possible 

impacts, and a few states require model output to be included in burn plans.2 Some 

users play "what-if" games with the models and use output from different burn scenarios to help discuss burn options with state regulators. Other users run models under 

various climate and burn scenarios to help in long-range planning and assessing environmental impact. Applications to wildfire are gaining interest, especially where 

models can help determine the effects of wildfire versus prescribed fire.

We categorized the types of users based on their typical applications and familiarity 

with modeling techniques as follows: 

1. Local project managers likely spend most of their time in the field, and thus 

typically cannot afford to learn or run complex computer programs. Smoke-dispersion 

models might be used to supplement information required to obtain burn permits or to 

help visualize the effects of various burning options. The models should be fast, 

require few input data, be easy to use, and run on a PC. 

2. Regional project managers may be in a fuels or smoke-management role. They 

often come from a field background and may have slightly more computer background 

than a local project manager. Smoke-dispersion models may be used to supplement 

information in an environmental impact assessment or to evaluate tradeoffs between 

prescribed burning and wildfire. Regional managers also may require that models run 

on PCs and be relatively easy to initialize and run. 

3. Regional systems managers may work most frequently with air-quality issues 

and thus have greater meteorology or computer background than regional project 

managers. Their job may be structured in a way that would allow more time for 

modeling; they may use smoke models in similar ways as regional project managers 

but are likely to deal with more complex issues or larger domains. They could have 

access and know-how to run both PCs and workstation-style computers. 

2

 Personal communication. 1994. Michael L. Sestak, U.S. 

Geological Survey, 240 W. Prospect St., Fort Collins, CO 80526. 

User Applications 
4. Research scientists should have the most knowledge of how to run and use 

smoke-dispersion models. They might test the sensitivities of models to various burn 

scenarios and model configuration options. They may be involved in interpreting 

model results and offering advice to managers on how to apply models appropriately 

for individual cases or large-scale assessments. 

Wildland smoke managers traditionally categorize models based on their anticipated 

application. These model categories are defined as follows: 

1. Research models are capable of modeling for many chemical components, gas 

and particulate concentrations, and a large radius of receptor sites and their dispersed 

concentrations. 

2. Regulatory models can be used for permit approval and would be capable of 

showing dispersion over large geographic areas (>10,000 acres). 

3. Planning models may apply to local or regional planning issues and could provide 

supporting data to help acquire burn permits for specific burns or report potential 

environmental impacts from various burn scenarios. These types of models should 

have the ability to run well in advance of an actual fire (greater than 1 year) and would 

be easier to use than research models. 

4. Screening models should provide users with a "worst case" scenario to determine 

if alternative burn plans are warranted or if more indepth modeling is required. Therefore, screening models can be quite simple, able to capture only the worst conditions, 

and easy to run. Field users concerned with smaller (10- to 100-acre) prescribed 

burns might use a screening model to aid in visualizing what fuel and weather 

conditions are best suited for the burn. Managers may use these simple models to 

screen for the effects of large fires or multiple fires. 

Currently, no model is used for making regulatory decisions about whether to burn. 

SASEM is used to support the obtainment of air-quality permits in several states, and 

some agencies are beginning to encourage the use of dispersion modeling to quantify 

smoke impacts in documents that report potential environmental impacts. All models 

were designed to supplement local expertise. Because no model has been officially 

validated for biomass burning,3

 regulatory use would be inappropriate at this time. 

Components of each model are summarized in table 1. The simplest models (for 

example, SASEM) seem to estimate many coefficients in the component equations. 

These models are computationally efficient and can function on the simplest 

computing platforms. Complex models (for example, TSARS Plus and CALPUFF) 

more fully derive each equation. These models can be computationally expensive 

and benefit from high-speed computers. Table 2 summarizes the computer 

requirements for each model. Some models request readily available input data, and 

model results are output in formats that match regulatory figures (see table 3).

3

 Some biomass smoke trajectories have been validated against 

observation data (for example, Hardy and others 1993) and several 

models use dispersion components that have passed the Environmental 

Protection Agency (EPA) approval process (for example, Lavdas, in press; 

Sestak and Riebau 1988; Scire and others 1995b) but the peculiarities of 

biomass burns have not been tested thoroughly enough for validation. 

Model Components 

4 
5
6 


Two of the models (NFSpuff and TSARS Plus) have internal digital elevation model (DEM) 

data. These necessitate large hard disk storage space (50 to 100 megabytes) for computer 

simulations. TSARS Plus should include topography for all Western states,4 but the version 

tested included only data for Wyoming. NFSpuff currently is restricted to the Western United 

States by its inclusive topography. CALPUFF requires users to supply their own DEM but, 

once supplied, makes automatic use of it.5

 Using DEM files allows easy selection of domain. 

The terrain data are used by each model to calculate surface trajectories. Also, output 

graphics are projected over topography. 

VSMOKE, VSMOKE-GIS, and SASEM were designed to function anywhere over relatively 

flat terrains and do not require DEM data. Topography can be part of an ArcView©7

project, however, if it is desired in output graphics for VSMOKE-GIS. VALBOX was 

designed to simulate smoke in a confined valley that users define by the dimensions of a 

box. 

SASEM, VSMOKE, and VSMOKE-GIS each model one burn at a time. ArcView, 

however, can plot the results of multiple burns from VSMOKE-GIS. CALPUFF, NFSpuff, 

VALBOX, and TSARS Plus all can model multiple burns simultaneously. 

Those models that consider the effects of complex terrain (NFSpuff, TSARS Plus, and 

CALPUFF) must simulate topographically forced surface winds. TSARS Plus and CALPUFF 

do this by interpolating observations to a three-dimensional grid (NUATMOS: Ross and 

others 1988 and CALMET: Scire and others 1995a, respectively). Both require at least one 

surface-wind observation and one upper air observation. NFSpuff currently estimates 

surface trajectories by extrapolating upper level winds. When upper level winds are 

decoupled from the surface or there are insufficient data, NSFpuff and CALPUFF can 

optionally approximate diurnally varying slope winds. Local valley inversions that affect 

mixing height may be simulated by TSAR Plus and CALPUFF if there are enough 

observational data to capture the local feature. NFSpuff and CALPUFF can imply local 

inversions with the diurnally varying wind options. 

Another consideration in modeling winds in complex terrain is that the ingestion of surface 

observations does not always improve simulations. In fact, surface-wind observations may 

degrade simulations if observation sites are influenced by fine-scale topography or land 

use that is below the model resolution and not representative of the burn site, as often is 

the case. Until fully physical meteorological models can simulate winds and mixing heights 

in real time below 1 kilometer spatial resolution (still some years away), some amount of 

parameterization for approximating terrain and land use effects on winds will remain 

necessary.

4

 DEM data for all Western states should be available in 1996 (see footnote 2). 

5

 Complete DEMs for the United States should be on a newly available compact disk 

for CALPUFF (Personal communication. 1994. Scire, Joe. Earth Tech, 196 Baker 

Avenue, Concord, MA 01742). 

6

 In this case, the terrain, whether flat or gently rolling, should not influence the 

direction or speed of near-surface winds, which control smoke trajectories. 

7

 The use of trade or firm names in this publication is for reader information and 

does not imply endorsement by the U.S. Department of Agriculture of any product 

or service.

Domain 

9
Weather Input 

Source Strength 

10 

Source-strength modeling is a weak link in selecting domains and modeling dispersion 

patterns in regions of complex terrain. In theory, all models that rely on the USDA FS 

emission production model (EPM) for their source-strength calculations should be restricted 

by fuel type to areas with vegetation common to the Pacific Northwest. Likewise, selection of 

the internal, source-strength algorithm option in VSMOKE should be restricted by fuel type to 

areas with vegetation common to the Southeastern United States. In practice, it is possible to 

circumvent this restriction by choosing Northwest (or Southeast) surrogates for actual 

vegetation type. 

Modeling dispersion patterns in complex terrain assumes a source of nonbuoyant or 

neutrally buoyant smoke, usually from smoldering, that follows topographically controlled, 

near-surface winds. Emission rates in the smoldering phase, especially the late stages of 

residual smoldering, are not properly accounted for in any of the available source-strength 

models (Ferguson and Hardy 1993, Lavdas 1982, Sestak and Riebau 1988). Therefore, 

even though smoke-dispersion models may be capable of simulating surface trajectories in 

complex terrain, by the time the burn reaches its residual smoldering phase, the 

source-strength models have unrealistically stopped generating smoke. 

Two models (NFSpuff and CALPUFF) allow input of time-varying, grid-point weather data 

files to represent upper air conditions. NFSpuff includes automated retrieval of preformatted 

nested grid model (NGM), 850 millibar data from the National Center for Environmental 

Prediction (NCEP) via a private vendor. If other grid-point data are desired for use with 

NFSpuff, then it is theoretically possible for users to acquire them and preprocess them to fit 

the format of NFSpuff. NFSpuff optionally allows users to input a time-invariant steering wind 

instead of a grid-point data file. CALPUFF can accept upper air grid-point weather data from 

any source, but users are required to perform all their own preprocessing to fit the input 

format requirements of CALPUFFCALMET. 

All other models require users to manually input weather-observation data. For SASEM and 

VSMOKE-GIS, this is a relatively simple task because only single values for wind speed and 

direction at the trajectory level are necessary. TSARS Plus requires at least one user input, 

upper air observation and improves with multiple observations from several different heights. 

CALPUFF uses hourly surface-observation data if they are preprocessed into the input file 

format of CALPUFF-CALMET. In TSARS Plus and CALPUFF, the more surface-observation 

stations there are, the more accurate the surface trajectories are modeled. VALBOX 

accepts a surface data record from one station for several time periods. NFSpuff currently 

uses no surface observations. 

Currently there are only three ways to estimate source strength from biomass burns for 

dispersion modeling: (1) EPM (Hardy and Ferguson 1994, Sandberg and Peterson 1984), (2) 

the internal algorithm of VSMOKE's (Lavdas 1982; Lavdas, in press), or (3) the internal 

algorithm of SASEM's (Sestak and Riebau 1988). Emission production model (EPM) was 

designed to model high-intensity slash burns in clearcut harvest residue in Washington and 

Oregon. It models heterogeneous fuel types and moisture regimes and considers slope and 

weather. Because emissions for each fuel type are empirically derived in EPM, it is not 

transportable to regions with different vegetation types. Regions outside of Washington and 

Oregon that use EPM must select Northwest fuel types that most closely match their own. The 

internal algorithm 
of VSMOKE is similar to EPM but relies more on user estimates of burn characteristics than 

mechanistic modeling and includes emission equations for fuel types in the Southeastern 

United States. The source-strength algorithms of SASEM are the simplest, assuming 

homogeneous fuel type and spacing of fuels. 

All models include or refer to EPM as a primary source-strength component option. VALBOX 

and TSARS Plus optionally include the source-strength component of SASEM. CALPUFF, 

VSMOKE-GIS, and VSMOKE can accept data from any sourcestrength model if it is 

preprocessed to fit a specified file structure (CALPUFF and VSMOKE) or keyed into an entry 

form (VSMOKE-GIS). Currently, however, only EPM is available as an external 

source-strength module. 

The biomass smoke-dispersion models tested for this assessment use three different 

standards for calculating dispersion: (1) box, (2) plume, and (3) puff. The box method 

assumes instantaneous mixing within a valley (VALBOX). These types of models usually are 

restricted to weather conditions that include low wind speeds and a strong temperature 

inversion that confines mixing height to within valley walls. The coordinates used to calculate 

box dispersions usually are fixed in space and time and thus called Eulerian coordinates. The 

plume method assumes that the smoke travels in a straight line under steady-state conditions 

(the speed and direction of particles do not change with time). SASEM, VSMOKE, and 

VSMOKE-GIS are plume models. The puff method simulates a continuous plume by rapidly 

generating a series of puffs (NFSpuff, TSARS Plus, and CALPUFF). All puff and plume 

models in this assessment assume that concentrations crosswind of the plume disperse in a 

bell-shape (Gaussian) distribution pattern. These models also use Lagrangian coordinates 

that essentially follow parcels as they move. 

Choosing a model for biomass burn simulations is not straightforward. If meteorological data 

are scarce or quick estimates of "worst case" conditions are desired, then plume models 

(SASEM, VSMOKE, VSMOKE-GIS) may be sufficient. The straight-line trajectories even may 

apply in mountain regions if the plume rises well above influencing terrain. Box models 

(VALBOX) also are a good choice for burns confined to a valley. Puff models (NSFpuff, 

TSARS Plus, and CALPUFF) are designed to address all conditions, from straight-line plumes 

and tortuous trajectories to simple valley slosh. They require, however, abundant and realistic 

input data that may not always be available to run properly. 

A complete scientific evaluation of smoke-dispersion models is beyond the scope of this work. 

Principle components (plume rise, trajectory, and dispersion) of all models, however, assume 

functions that are consistent with standard, Environmental Protection Agency-approved, 

industrial stack-emission models. This was most easily discovered in user manuals citing 

peer-reviewed literature from which model theories and methods are based, or those manuals 

that include complete derivations of model-specific equations. 

Primary differences in physics between the models seem to be the degree to which they fully 

derive equations. All models include some empirical coefficients, approximations, or 

parameterized equations when insufficient input data are expected or when faster 

computations are desired. The degree to which this is done differs among models and 

between components of each model.

11

Plume 

Trajectory and 

Dispersion 

Model Physics 
Note that it is not clear whether fully physical calculations of plume rise and dispersion 

are more accurate than approximate calculations in biomass burning. There is a high 

degree of uncertainty in modeling source-strength of biomass burns. The burning 

material is scattered and highly variable in composition. Also, burn rates are time 

varying and influenced by ambient weather, ignition patterns, complex slope topography, and structure of surrounding vegetation. The plume rise component retains the 

broad uncertainty of source-strength heat-release calculations. Likewise, dispersion 

components retain the broad uncertainty of source-strength emission composition and 

release-rate calculations. 

Only CALPUFF includes simple atmospheric chemistry to convert S02 to S04 and 

NOx to N03. None of the other models include any atmospheric chemistry. Available 

source-strength modules for biomass burns, however, do not generate S02 or NOx,

so the chemistry option of CALPUFF would not apply to biomass burns at this time. 

Output variables of all biomass smoke models, therefore, are the result of dispersed 

input variables (currently from EPM or internal algorithms of SASEM or VSMOKE). 

Depending on the output file format and which method is used to estimate emissions, 

output variables of each model include one or many components of the following 

particles and gases: 

TSP Total suspended particles 

PM10 Particles having diameters less than 10 microns 

PM2.5 Particles having diameters less than 2.5 microns 

PM Particulate matter (TSP, PM10, or PM2.5) 

CO Carbon monoxide 

C02

 Carbon dioxide 

CH4 Methane

All models output concentrations of particles with distance from the source. All but 

VSMOKE-GIS and VALBOX output time-varying information on concentrations. 

The type of concentrations variously include average, total, maximum, 1 hour, and 

24 hour. The specific outputs for each model are summarized in table 3. 

VALBOX, VSMOKE, and SASEM have strictly tabular output. TSARS Plus includes 

internal graphical displays as well as tabular files. NFSpuff plots TSP with time in 

planar, cross-section, or oblique views over gridded topography. In addition, NSFpuff 

displays dot-contour maps of maximum and 24-hour average TSP concentrations. 

TSARS Plus plots 1- and 24-hour PM10 concentrations over a grid. The plume path 

is shown over a contour map of topography. To determine concentrations in relation 

to topography with TSARS Plus, it is necessary to cross-reference the trajectorytopography map with the concentration map and a table of concentration values. 

VSMOKE-GIS is linked to ArcView for graphically viewing isopleths of total surface 

PM concentrations as a geographical information system (GIS) overlay. Tabular 

annual or run-length output files in CALPUFF include location data so that the files 

can be postprocessed for export to external graphics programs.8

8

A newly available compact disk for CALPUFF includes 

graphics simulation software (see footnote 5). 

Output Variables 

Output Products 

12 
na = not available. a SASEM , VSMOKE, and CALPUFF have passed EPA requirements for regulatory dispersion modeling. It is the 

opinion of the authors that the peculiarities of biomass burns in wildland areas have not been tested thoroughly enough for validation. 

Therefore, no model is recommended for regulatory applications at this time. 

The appendix describes in detail the effort required to obtain a reasonable output 

from each model. SASEM and VALBOX were the easiest to use. Burn experience is 

necessary, however, to be able to select appropriate dispersion-day indices and 

mixing heights. VSMOKE and VSMOKE-GIS were quite easy, also, but ArcView required a steeper learning curve. Prior GIS experience would help to run VSMOKEGIS. In addition, burn experience would help in selecting appropriate stability classes, 

plume rise speed, and transport wind for VSMOKE and VSMOKE-GIS. NFSpuff was 

very easy, prior burn experience is unnecessary to run it, and meteorological input 

data are readily available. TSARS Plus was moderately difficult to run, mainly 

because of poor error trapping9

 and intensive key punching required to enter input 

data. CALPUFF was designed for flexibility. Therefore, it necessarily requires time to 

learn about all input, run, and output options, and configure the program to fit individual modeling tasks. Once set up, however, the program runs smoothly. Locating 

sufficient meteorological input data for TSARS Plus and CALPUFF could become 

difficult, or at least time-consuming. 

This assessment considered ease of use, availability of input data, and format of 

output data. None of the models has all components necessary for any of the four 

categories of application (research, regulatory, planning, and screening). There are 

some basic characteristics of each model, however, that lend it to one or another of 

the other model application categories. 

Based on our user-assessment of the currently available versions and a cursory 

understanding of user needs and abilities, we have attempted to suggest appropriate 

applications for each model. These are described below and summarized in table 4. 

9

 A newer version has better error trapping (see footnote 2). 

Conclusions 

Ease of Use 

13
CALPUFF has so many alternatives for model input and such well-documented science 

that it can benefit most research projects. It has only two options for dispersion 

calculations (both Gaussian approximations), however, which may limit its ability to 

research all variations of biomass burning. The ability of CALPUFF to model an unlimited 

number of burns over an unlimited area make it ideal for large-scale planning applications. 

Its difficult configuration requirements may cause local and regional project managers and 

those with limited computer experience to avoid using CALPUFF. 

TSARS Plus has similar model components to CALPUFF and thus is similarly applicable 

to research problems. In addition, it includes five alternatives to calculate dispersion (each 

Gaussian approximations) that may make it a more interesting tool than CALPUFF. Its 

current choice of topography restricts its use to Wyoming. In addition, the reliance on 

user-input data instead of file reads make it an unattractive tool to most researchers. Only 

five simultaneous burns are possible, and the tedious input requirements also make it a 

difficult tool for planning. Its cumbersome error-trapping (see footnote 9) limits its 

applicability to those with computer experience. 

NFSpuff is fast, easy, and visually pleasing to run. Little or no prior computer or burn 

experience is necessary to use it. It is an ideal screening tool. Also, because it can model 

up to 100 burns simultaneously over a broad geographical area, it may provide a 

reasonable planning tool. Its current reliance on NGM data limits simulations with 

time-varying weather to 48-hour periods. The optional user-input steering wind and 

diurnal-varying surface wind, however, may allow reasonable long-period simulations for 

regional haze issues. Its science is not as well documented as CALPUFF or TSARS Plus, 

and it is limited by its choice of topography to the Western United States. It may not be 

appropriate, therefore, as a research tool. 

VSMOKE and VSMOKE-GIS easily simulate one burn at a time. The link with ArcView 

makes VSMOKE-GIS a wonderful tool for quick screening or simple project planning. 

ArcView also allows the results of multiple burns to be viewed simultaneously. The 

period-by-period tabular output of VSMOKE allows detailed project planning. Both 

models are limited to regions of flat or gently rolling terrain. The ability of VSMOKE to use 

EPM10 (or data from any other source-strength model) extends its use to relatively flat 

terrain in the Western United States. 

VALBOX is designed for and is a reasonable choice for screening burns that are confined 

to simple valleys. It has a specific application and is not meant for planning or research. 

SASEM is the easiest of all models to run and is perfect for anyone from a field 

technician on up who wants to screen individual burns. Its tabular output makes it more 

difficult to use as a planning tool, but because it has more output options than NFSpuff, it 

may be better for project planning in the Western United States as long as the domain is 

relatively flat.

10 The option to use an EPM-created data file was turned off in the 

VSMOKE-GIS version available for this analysis. Output from EPM, or any 

other source-strength model, however, may be hand entered from one of the 

entry-form screens of VSMOKE-GIS (see footnote 1). 

14 
Of the models tested, only SASEM and VALBOX have ceased development. In other 

models, the physics appear relatively stable, but user interfaces and output formats are 

changing. In addition, program bugs are being fixed. It is clear that all models would benefit 

from some improvement. Without a strict model comparison against a reliable set of 

validation data, it is impossible to determine which model is best or even the most realistic. 

Therefore, it would be unfair to recommend the use of one model over another based solely 

on this preliminary evaluation. 

There are at least three critical areas, however, that necessitate additional work before 

any model improvements can be realized: 

1. A source-strength model must be developed that can be applied to all vegetation types 

and burning scenarios, including wildfires and the residual phase of smoldering that is 

common in prescribed understory burns. 

2. Smoke trajectories in complex terrain require improved methods of simulating fineresolution slope winds. 

3. Data on particle and gas concentrations in and around biomass burns must be coupled 

with data on ambient weather and fuel conditions to validate smoke-dispersion models. 

Currently, only data from lofted plumes (acquired by tower-mounted sampling packages, 

aircraft, and satellite) are available for validation. None of the models can be used for 

regulatory applications, and no model can be recommended for use over another until this 

type of validation occurs. 

In addition to the above, improved access to available weather data would greatly 

improve accuracy and ease of use. 

1. The USDA Forest Service and Bureau of Land Management, remote automated weather 

system (RAWS) data should be made more easily available from the USDA Forest Service 

weather information management system (WIMS) computer. The WIMS user interface 

should be modified to make command-line download links possible so that RAWS data 

from selected sites may be automatically retrieved and available for smoke-modeling input. 

2. Grid-point weather data (for example, NGM and other NCEP model output) and radiosonde observation data must be more accessible to government offices. For example, a 

contract with the National Weather Service could be made to transfer data twice daily to 

WIMS, where it would be accessed by smoke-model users. Currently, these data are 

purchased through private vendors. 

To take advantage of the various modeling techniques and considerations of input 

availability, a reasonable approach for future development would be to build a fully functional 

modular framework (for example, Bevins and Andrews 1993). A truly modular system would 

be able to select appropriate components that match available input data and user output 

requirements. 

This work was supported by the U.S. Department of the Interior, Wildland Fire Research 

Initiative. Many thanks to Larry Mahaffey for his support and guidance. Helpful instruction 

and reviews by each modeler (Halstead Harrison, Mike Sestak, AI Riebau, Bill Jackson, 

Leonidas Lavdas, and Joe Scire) were much appreciated. In addition, the insightful 

comments and suggestions from Colin Hardy were invaluable.

15

Acknowledgments 

Recommendations 
Bevins, C.D.; Andrews, D.L. 1993. The Loki software architecture for fire and ecosystem 

modeling: a tinker toy approach. In: Proceedings of the 12th conference on fire and 

meteorology; 1993 October 26-28; [Meeting location unknown]. Jekyll Island, GA: Society of 

American Foresters: 252-259. 

Environmental Systems Research Institute, Inc. 1994. ArcView. Redlands, CA. 98 p. 

Ferguson, S.A.; Hardy, C.C. 1994. An aspect of modeling smoldering emissions. 

International Journal of Wildland Fires. 4(3): 135-142. 

Fox, D.G.; Dietrich, D.L.; Childs, J.E. 1983. Topographic air pollution analysis system 

(TAPAS) user support documentation. Fort Collins, CO: U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Forest and Range Experiment Station. 60 p. 

Hardy, C.C.; Ferguson, S.A.; Speers-Hayes, P. [and others]. 1993. Assessment of PUFF: 

a dispersion model for smoke management. Final report to U.S. Department of Agriculture, 

Forest Service, Pacific Northwest Region. Portland, OR: U.S. Department of Agriculture, 

Forest Service, Pacific Northwest Research Station; Pacific Northwest Region. 32 p. 

Harrison, H. 1995. A user's guide to "PUFFX": a dispersion model for smoke management 

in complex terrain. Mercer Island, WA: WYNDSoft Inc. 42 p. 

Hummel, J.; Rafsnider, J. 1995. TSARS plus smoke production and dispersion model 

user's guide. Preliminary Draft 7.95 . National Biological Service and the Interior Fire 

Coordination Committee. 96 p. Unpublished report. On file with: Environmental Science 

and Technology Center (ESTC), 2401 Research Blvd., Suite 205, Fort Collins, CO 80526. 

Jackson, W.A. [In preparation]. VSMOKE-GIS manual for ArcView. Asheville, NC: U.S. 

Department of Agriculture, Forest Service, National Forests in North Carolina. [Not paged]. 

Lavdas, L.G. 1982. A day/night box model for prescribed burning impact in Willamette 

Valley, Oregon. Journal of Air Pollution Control Agency. 32: 72-76. 

Lavdas, Leonidas G. [In press]. Program VSMOKE - user's manual. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. [Not 

paged]. 

Ross, D.G.; Lorimer, G.S.; Liuqiong, Li; Smith, I.N. 1987. CITPUFF: a Gaussian puff 

model for estimating pollutant concentration in complex terrain. CAMM Rep. No. 21/87, U.S. 

Department of Agriculture, Forest Service contract no. 28-K6-378, TAPAS Operational 

development and demonstration under a subcontract from Air Resource Specialist, Inc., Fort 

Collins, CO. 72 p. Unpublished report. On file with: Chisholm Institute of Technology Printing 

Services, 900 Dandenong Road, Caulfield East, Vic. 3145 (Australia). 

Ross, D.G.; Smith, I.N.; Mannis, P.C.; Fox, D.G. 1988. Diagnostic wind field modeling for 

complex terrain: model development and testing. Journal of Applied Meteorology. 27: 

785-796.

16 

References 
17 

Sandberg, D.V.; Peterson, J. 1984. A source strength model for prescribed fires 

in coniferous logging slash. In: Proceedings of the 21st annual meeting of the Air 

Pollution Control Association; 1984 November 12-14; Portland, OR. Seattle, WA: 

U.S. Department of Agriculture, Forest Service, Forest Residues and Energy 

Program. 10 p. 

Scire, J.; Insley, E.M.; Yamartino, R.J.; Fernau, M.E. 1995a. A user's guide for 

CALMET meterorological model. Doc 1406. Concord, MA: Sigma Research/Earth 

Tech. 221 p. 

Scire, J.; Strimaitis, D.G.; Yamartino, R.J.; Xiaomong, Zhang. 1995b. A 

user's guide for CALPUFF dispersion model. Doc. 1321-2. Concord, MA: 

Sigma Research/Earth Tech. 315 p. 

Sestak, M.L.; Marlatt, W.E.; Riebau, A.R. 1989. VALBOX: ventilated valley box 

model. 32 p. Unpublished report. On file with: Michael Sestak, U.S. Department of 

the Interior, Bureau of Land Management, and Colorado State University, Environmental Science and Technology Center, 2401 Research Blvd, Suite 205, Fort 

Collins, CO 80526. 

Sestak, M.L.; Riebau, A.R. 1988. SASEM simple approach smoke estimation 

model. Tech. Note 382. Denver, CO: U.S. Department of the Interior, Bureau of 

Land Management. 31 p. 

Wood, M.C.; Marlatt, W.E. 1980. The impact of growth on air quality in 

Telluride valley–a modeling assessment prepared for the town of Telluride, 

CO. Fort Collins, CO: Marlett and Associates. 44 p.
18 

In testing these programs, the technical background and computing resources that 

typically may be available to a local burn boss or regional fire and smoke manager 

were assumed. The goal was to determine what steps were necessary and how easy 

it was to achieve a reasonable output. No attempt was made to perform rigorous product testing or validate the accuracy of output data. 

A laptop computer was used for testing (486 DX50 MHZ, 8 megabytes system ram 

and a 4 MB permanent swap file). MSDOS 6.22 and WINDOWS 3.11 were the 

operating systems used during the test. Each program was run once or until complete 

model results were achieved. The models then were run through twice more to ensure 

that outputs were consistent. If the model was a native DOS program, it was first run in 

that operating system. The model was later run in a DOS Virtual Machine (VM) under 

Windows to see if all functions worked properly in that operating environment. Note 

that WINDOWS-95 was not used and there is some indication of potential 

incompatability. 

All programs were tested with a similar set of input data to ensure some consistency. 

Test data were collected at a prescribed understory burn about 40 miles southwest of 

Bend, Oregon, at Pringle Falls Natural Research area on May 18, 1995. The surface 

winds during this burn had low speeds and shifting directions. The Pringle Falls data 

were used as input for all the programs tested because not all of the five models 

provided sample data sets. The Pringle Falls data also included visual observations of 

smoke and data from an onsite nephelometer. 

Seven dispersion models, VALBOX, SASEM, VSMOKE, VSMOKE-GIS, NFSpuff, 

TSARS Plus, and CALPUFF were tested during summer 1995. Modelers were given 

a draft copy of this assessment document in September and have since fixed many of 

the errors and problems reported below. All but SASEM and VALBOX remain in 

development mode as of November 1995. Of these, NFSpuff probably was closest to 

being "user ready" at the time of testing. All models could add or change functions if 

given enough support to do so. 

All models had user interactive prompting or dialog input. All the software packages 

received were virus free. Two of the seven models, CALPUFF and VSMOKE-GIS, 

offer WINDOWS-based user input, whereas NFSpuff, TSARS Plus, SASEM, 

VSMOKE, and VALBOX are DOS based. One of the five programs (VSMOKE-GIS) 

offers GIS graphic display for viewing final products. NFSpuff offers graphic display of 

concentrations, and TSARS Plus has tabular and graphics output. SASEM, VSMOKE, 

and VALBOX offer tabular data reporting. 

All the models use EPM to calculate fire emissions of particulate matter (TSP, PM10, 

and PM2.5) and carbon gases (CO, C02

, and CH4). The EPM has emission factor 

data only for biomass species in Washington and Oregon. VSMOKE and 

VSMOKE-GIS have an option for an internal algorithm to calculate emissions for the 

Southeastern United States (see text footnote 8). In addition, SASEM has an option 

to use its internal algorithm to calculate emissions from homogeneous fuel types. 

Appendix 

Testing Technique 

Software Model Review 
19 

SASEM [version 3.0, 1989]–SASEM is part of the Tiered Smoke/Air Resource System 

(TSARS3), along with VALBOX and EPM. SASEM was designed as a screening tool for 

prescribed burns and was not intended for use with large wildfires. It addresses the 

regulatory needs for ensuring air-quality impacts under controlled burning situations for 

Federal lands. It has been adopted by the states of Colorado, Wyoming, New Mexico, and 

Arizona as the default software tool for burn planning. SASEM was not designed to integrate 

topographic influence, low wind speeds, or multiple fires. 

The program installation is quick and has a small memory footprint while running, thereby 

allowing use on a wide range of processors with base memory of 512 kilobytes or greater. No 

problems were noted running in either native DOS or in a DOS VM under Windows. SASEM 

offers straightforward command-line questions for user input but does not allow file saving or 

retrieval of user-created datasets. Default output files are overwritten on each invocation of 

the program. This forces users to turn to the DOS command line if they are interested in 

cataloging their work. This also forces users to complete all desired combinations for fuels, 

site, and weather input in a single sitting. The addition of file sharing would greatly improve 

the program. 

SASEM took less than 1 hour to run during the initial test, which indicated the ease of using 

the program. No errors were encountered other than disabling of the print commands in the 

TSARS3 batch file. This batch file must be edited if no printer is attached.1

SASEM is limited to 100-kilometers downwind dispersion, which is the limit of the Gaussian 

plume model used. Users are expected to be familiar with the "dispersion day scale," with no 

definitions given. Up to 10 downwind receptor sites can be defined. If SASEM emissions are 

used, the fire duration is defined by the user. If EPM emissions are used, duration is until the 

heat produced becomes less than one calorie per second. 

Output products for SASEM are geared toward screening for prescribed burns and regulatory 

emission control. The default product is a tabular data set that combines all the possible 

combinations for dispersion conditions, incremented wind speed, estimated concentrations, 

and plume height. The estimated concentrations are listed as either no violation, or the 

distance range (miles) for which the primary or secondary particulate standards are exceeded. 

Interpretation of the results by those not familiar with the format takes some time. The receptor 

sites only are referenced in the optional Visibility Table data set. This summarizes the possible 

combinations of receptor site, "dispersion day," wind-direction range, and two different visibility 

scales. Again, this output requires equal time to interpret if users are not familiar with the 

scales involved.

1

 Although not described in the user manual, it was learned later that simply typing NUL 

when asked for, "Name of list device [PRN]:" will eliminate this error (Personal 

communication. 1994. Sestak, M.L.; Riebau, A.R. U.S. Geological Survey, 240 W. Prospect 

St., Fort Collins, CO 80526).
20 

VALBOX [version date 01/90]–VALBOX, like SASEM, is part of TSARS3. VALBOX requires 

14 steps to define a box representing the volume of a mountain valley and its weather 

components. Wind direction and speed also are user-defined values that can vary with time. 

Emissions data can be used from the other two modules or calculated from within VALBOX. 

VALBOX allows data file access. Users select the output time format and the duration of the 

burn. 

VALBOX requires a steeper learning curve than SASEM on how to define the input variables. 

Good error handling is accomplished by repeating the current prompt if an answer has been 

miskeyed during the text input. For incorrect numeric responses the message, "value may be 

too low (or high) / do you wish to keep it Y/N?," is returned. Nowhere in the manual were 

minimum and maximum values listed for numeric input options or what would happen to the 

program results if the questionable input values were used. Minimal explanations for each 

question can be accessed by typing a question mark followed by a carriage return at the 

current command prompt. At times, users may wish for a little less brevity. All modules come 

loaded with default entries for each item, which can speed user input after the user becomes 

familiar with the programs. 

The wind-input format is the poor person's "regime modeler," where inventories can be built, 

saved, and reused later. At each time prompt, variations in wind speed (mph) and direction 

(denoted by + for up valley and - for down valley) can be entered. This is tedious when entering 

several varying winds because, although the program seems to allow a large number of wind 

inputs, it allows users to edit only a small number. It would be helpful if the wind input option 

could use delimited text files or local weather datasets collected by remote stations. Currently, 

the user-input scheme is not efficient. In addition, air buoyancy and its relation to temperature 

and relative humidity is ignored. These factors need to be considered. Another input box for 

wind-speed units would save lots of conversion work. 

The current user-input requirements were awkward and left little desire to continue after the first 

half hour, especially with runs that included shifting wind direction and that exceeded 24 hours. 

The initial test took 1.5 hours to produce a result. The learning curve is tedious and takes a 

dedicated user to become proficient. Defining the box or boxes for the model is time-consuming 

and would be improved by using digitized maps. The tradeoff here is that the programming 

effort, hardware and system requirements for digitizing would increase the scope of the model 

substantially. 

VALBOX produces a tabular data set for TSP, with the default concentrations output at a 

user-specified time interval. In addition, run-time averages of concentrations may be requested. 

Users must run the model through two additional loops to obtain a printout of PM10 and CO 

concentrations. A user-definable selection for one or all of the outputs at a single command 

prompt would be good. The manual states that the model is for very low wind speeds. Wind 

speeds at Pringle Falls were often below 1 mph, which raised the, "value may be too low / do 

you wish to keep it Y/N?," warning during user input. This is a thoughtful reminder that few 

instruments can measure very low wind speeds accurately, thereby allowing users to 

reconsider or continue.
VSMOKE [version 19950128] and VSMOKE-GIS [version date 04/95]–VSMOKE

was initially written to determine potential visibility reduction for motorists and is a dispersion 

model only. VSMOKE can be used to estimate visibility if the relative humidity is < 70 percent. 

VSMOKE uses a Gaussian dispersion algorithm based on industrial smoke-stack emissions. 

The program currently comes in two versions, DOS (VSMOKE) or a visual basic (VB) 

front-end (VSMOKE-GIS) that preprocesses user input for display in ArcView. 

The copy received for the evaluation was the VSMOKE-GIS for Windows beta version 

(Jackson 1995). A draft manual was included with the software with reference to Lavdas (in 

press). The brevity of the manual was good. Description of some key input variables of the 

main GIS Input Form VSMOKE-GIS's, however, were missing. Others were worded so the 

tester had to truly test by trial and error to achieve success, which caused confusion. No 

onboard help was available within the program. 

Initial installation of VSMOKE-GIS is quick and easy. A VSMOKE-GIS group is created 

automatically for Program Manager in Windows with an internal VSMOKEGIS icon. When 

fully loaded, VSMOKE-GIS uses about 190 kilobites of the available system resources. 

Although the geographical user interface (GUI) is attractive, use of the tab key, instead of the 

mouse, to move between input boxes leads users on a trail of confusion. The program was 

sensitive to user input, and it crashed or trapped an error issuing an alert box) and then 

terminated the program on seven different occasions. Users need seven steps to calculate 

downwind PM concentrations for prescribed fires. The initial time required to successfully 

complete all form options and save the appropriate files for ArcView was quick and easy. It 

required about 4 hours, however, to resolve problems of loading and running ArcView. 

Weather-input options include one single user-defined wind direction for the duration of the 

dispersion run, a transport wind speed, mixing height, and atmospheric stability class. Check 

boxes exist for the period of daylight and the expected plume-rise speed (a qualitative value 

based on the user's guess). Site data includes universal transverse mercator (UTM) grid 

coordinates, fire size, and background concentration level. 

Total emissions are not calculated in VSMOKE-GIS. Instead total source emission rate for PM 

(grams per second) and total sensible heat emissions (megawatts) were calculated by the 

program from the Calculations menu option. This form allows users to choose fuel type, 

loading, smoke duration, and fire length. To finish this form, choose the Calculate button and 

the Use Answer button; the results are entered into the main GIS Input Form. It is important to 

remember to enter the size of the fire (acres) on the main input form before using the 

Calculations module. If not, the program returns a <"Type Mismatch Error'> message and 

terminates. 3

2

 A newer version has fixed this error (Jackson, see text footnote 1). 

3

 A newer version has changed this to allow users a second chance to input fire size 

(Jackson, see text footnote 1). 

21 
Fuel moisture is not directly put into the program. Instead it is implied by the user input value of 

proportion of emission subject to plume rise. This also allows for a calculated departure from the 

industrial stack emissions to determine what percentage of total smoke will rise. Full scale for the 

proportion of emissions subject to plume rise is -1 to +1, with values less than 0 for low fuel 

moisture (-0.75 default) and anticipated heavy smolder, and values greater than 0 for fast-burning 

fires, that is, low fuel moisture (0.5 to 0.9 recommended). 

Output options include up to 1004

 user-selectable isopleths for graded PM concentrations 

(micrograms per cubic meter) available by clicking on the Set spacing interval button in the GIS

Input Form. This loads the DownWind Interval form. At first this form is tricky to use, as some 

objects are controls and some are not. The instructions in the manual for this could be better. Also, 

you can assign a tolerance level for each PM concentration, which can speed computation for the 

isopleths. The downwind calculations have a maximum distance of 100 kilometers. 

Once users are familiar with ArcView and the GIS Input Form, the strength of this model is realized 

in the amount of burn scenarios that can be developed and displayed efficiently. VSMOKE-GIS 

currently does not supply terrain data and has been developed for use in gentle, rolling terrain. A 

single steering wind is constant for the concentration trajectory. The difference in using three and 

seven isopleths slows the computer somewhat. A valid consideration in this software suite is the 

learning curve needed to develop new projects. In some ways, this may limit the number of users 

fully using this application. Because ArcView uses UTM grid system, it would be handy if

VSMOKE-GIS contained a module to convert latitude and longitude to UTM. 

A tradeoff does exist in hardware overhead for use of ArcView, and requires these hardware 

options: 

• At least a 486DX processor 

• WINDOWS 3.0 or greater 

• 12000 kilobytes of virtual memory 

• Accelerated Windows-type graphics card (advised) 

• Config.sys needs to have files=65 

• compact disk drive 

• UTM easting coordinate system 

The weaknesses centered around the user-interface of VSMOKE-GIS. If a GUI interface is used, 

all effort should be made to make it as simple as possible for users to achieve results, otherwise 

the purpose is defeated. A novice user would potentially become frustrated with the input form. 

Items that added to this problem were: 

• Error trapping that ends in program termination, with a <"Type mismatch error"> 

message being the most common5

4 A newer version has changed this to 10 isopleths (Jackson, see text footnote 1). 

5 A newer version has fixed this error (Jackson, see text footnote 1).

22 
Standard Windows conventions were not followed, especially with default command 

keystrokes for standard commands (for example, alt+F / O for file open) and mouse clicks or 

double clicks 

Alert boxes were uninformative, which did nothing to help user before program termination 

NFSpuff [Version 1.16x, 7/14/95]–NFSpuff uses three modules for user input: 

• Emissions (Modified USFS EPM) 

• Weather (For obtaining and displaying radiosonde observation data and 700 mb and 

850 mb data from NGM) 

• Trajectories (Defines model domain and topographic grid resolution, assigns emission 

and weather data files, and plots simulated plume and TSP concentrations) 

The manual is well thought-out, and provides useful information in a concise guide orientated 

towards the end user. The initial part of the manual guides users-through the major functions of 

the program. More technical information about the scope of the software is in the appendices or 

available request from the developer. No printer support is offered in the program; rather a screen 

capture utility must be used to produce hard copy graphics output. 

Full installation takes 44 megabytes of hard disk space; increased terrain files are the main 

factor for increased hard drive footprint. The install program is simple and offered no problems. 

The useability of the accompanying manual is equal to its predecessors. All portions of the 

software have no problem running in native DOS or in a DOS VM from Windows. 

The user-input scheme is menu driven with each module treated separately. Once a module is 

selected, a list of input questions is presented. If out-of-range values are entered, a help screen 

appears defining the variable limits along with a prompt for entering a legal value. This provides 

a "no questions asked" format and good error trapping. All selections in this program are 

keyboard driven; mice are not supported. The software allows saving and editing of all module 

data by unique names. Formatted output files for maximum concentrations are overwritten on 

each run from the Trajectories module. 

The Trajectories module allows users to define the modeling domain by latitude and longitude of 

its northwest corner through a graphic interface. Users can select 1, 2, 4, or 8 kilometer grid 

resolutions for the plotting area, depending on the domain size. This selection process requires 

practice, but is intuitive and efficient. 

The finished planar view terrain map shows burn sites and population centers as different sized 

red circles (towns with less than 1,000 population are not shown). The map also shows roads, 

rivers, lakes, and railroads (all user display options). NFSpuff offers terrain maps for the entire 

Western United States and parts of Canada. At this point, the capabilities of NFSpuff may be 

outstripping EPM. Forest types for areas outside Washington and Oregon are not currently 

cataloged in EPM lookup tables for fuels. The generated maps can be saved for future use. Once 

these steps are completed, users can recall any of the separate data files from within the 

Trajectories module.

23 
Output also is generated from the Trajectories module by choosing a terrain map, emission files, 

and weather file (NGM) or optional user-input steering wind. Other options from the Trajectories 

Operation Menu include selecting optional surface-wind algorithms. Surface winds either can be 

extrapolated from NGM 850 millibar winds and adjusted for conservation of mass around the 

topography, or as "thermal slosh" by initiating a new algorithm. Use of the "thermal slosh" defaults to 

follow a simple sinusoid, with a maximum up-valley wind at 2 p.m. and down-valley at 2 a.m. The 

program analyzes the topographic map and defines the long axis of the valley. The extrapolated 

winds are based on thermal gradients adjusted for the terrain. Presently, importing of real 

surface-wind data is not supported. 

Also in the Trajectories Operations Menu is an option to display or revise dispersion coefficients. 

This primarily is geared towards the advanced user and allows considerably more manipulation of 

the system. User-edited variables include: 

• Surface temperature 

• Temperature-lapse rate 

• Puff-emission interval 

• Eddy diffusivity (hotter fires >= 50, cool fires <= 50) 

• Plume-entrainment coefficient 

Another option is the choice between cumulative and transient graphic displays. The former is the 

default display that allows the time-lapse exposure of plumes through their rise and decay process. 

The transient mode traces single puffs about the screen, and can help visualize the trajectory of 

individual puff particles. Note that this mode erases the map pattern as its trajectory is plotted over 

the topography. 

Final products include a real-time graphic display of color-coded concentration levels in simulated 

animation overlaying the terrain map. During the model run, users can pause the display or request 

cross-sectional plots of the plume heights. Users define the azimuth for these cross sections. An 

oblique terrain perspective plot also is available from this menu, which once again simulates the 

dispersion of color-coded puffs. 

A plot of maximum and 24-hour average concentrations is generated over topography when you exit 

the main puff simulation. The data for these two concentrations are written to individual files 

(mapname.max and mapname.avg). If users are interested in cataloging these files, it is necessary 

to rename them, as the files are overwritten if the map is reused for different burn scenarios. 

The user interface, graphic output, and speed of NFSpuff make it pleasurable to use. The ease of 

achieving results and the speed of graphic displays are very good. 

TSARS Plus [version 1, 7/24/95]–TSARS Plus is the next generation of TSARS3 and is a 

DOS-based application. SASEM and EPM are the only code modules brought forward to this new 

software. All other supporting modules are new. Both formatted reports and graphic displays are 

user-output options. The software now offers terrain support for generating the wind file and 

contour map. The version received for testing had only the terrain maps for Wyoming included 

(see text footnote 4).

24 
The installation process for the six system disks program runs well if you use the setup defaults. Changes to 

these defaults will crash the install program unless users edit the Ezi.cfg file on disk one of the set. Other install 

characteristics are: 

• Traps wrong disk 

• Tries to change config.sys to files = 99, buffers =20 

• Wants to add \tsarsp to your path 

• Copies tsarsp.bat to the boot drive of your machine 

These hardware and software requirements (listed in the manual) are recommended: 

• 11 to 20 megabyte disk space for installation 

• 486dx 50 MHZ processor (33 MHZ will do in a pinch) 

• 8 megabytes RAM 

• A burn project can take 3 megabytes of space 

• terrain maps can take 7 megabytes 

• The program runs in 3 megabytes 

• Share.exe cannot be used simultaneously with TSARS Plus 

• The program requires MSDOS 6.x or greater (recommended due to its Multiple config.sys and 

autoexec.bat options) 

• Cannot be run in a DOS VM under Windows 

• A laser printer required for tabular reports and graphics 

• A dot matrix printer for tabular reports only 

• It is not network compatible 

Because this is a file-intensive program, the manual says to always use File / Quit to exit the program. If users 

do not use File /Quit to exit, the indexed database filing system will not write all open files properly to disk, 

leaving users with lost clusters, orphaned files, and damaged indexes. Users should see a message, "Foxpro 

normal shutdown," when exiting from the program in this manner (we never did). 

A manual, draft 7.95, was included with the software. It describes in adequate detail the steps necessary for 

completing a burn project. Tips are highlighted in bold type, and are appreciated. Examples of output products 

are given in an appendix of the manual. 

A modular template and building block system is used to create the essential data necessary to define a burn 

project. All the template data are stored and are reusable or can be modified for use in other burn projects. Users 

must follow the TSARS Plus Steps to Success flowchart to expect results from the program. This can be 

displayed on screen and is also in the manual. Predefining of all components of step 1 are necessary before 

defining a burn project. All the templates and building block functions are found under the Database menu option. 

The software uses data-input forms,

25 
which are then saved as database records. As this inventory of information grows, users are 

allowed to query the database for specific records with the Find function for all the template 

categories. This is a good option that can speed access to desired data. 

Because all pieces of step 1 share latitude and longitude coordinates, the user needs to know the 

size and latitude and longitude coordinates of the final burn project to adequately assign receptors 

and all other template groups. 

The first steps require setting up fire and receptor definitions, which are straightforward 

processes. If EPM is used, TSARS Plus uses the heat release rates of EPM to calculate plume 

rise. If the source strength of SASEM is used, TSARS Plus uses internally calculated plume rise 

of SASEM. 

Next, users need to define the meteorological stations and associated wind data for those 

stations; the number of user-created stations is unlimited. Stations are defined by latitude, 

longitude, and elevation. Basic data for the stations include surface wind speed, direction, 

stability class, mixing height, and air temperature. Once these are assigned for a particular date 

and time, users have the option to assign upper air observations for that same time period. Users 

will find later that multiple levels of upper air data are required. The manual does not explain this, 

which can result in having to backtrack to complete the projects 

The last requirement for building templates is defining the wind files. This requires users to 

define the latitude and longitude coordinates of the northwest corner of the project and three 

user-input scenarios: 

1. Domain size. (100, 200, or 300 square kilometers) 

2. Met station. (Selection of meteorological stations from a list of those that lie within the defined 

domain) 

3. Met station data. (Selection of data by name, date, and time) 

Completion of these steps produces a Generating Wind Field File dialog box. Three-dimensional 

wind fields are generated by the NUATMOS meteorological model. Meanwhile, the terrain map is 

created from a subset of TAPAS (Fox and others 1983) terrain data. The wind field output takes 

about 3 to 4 minutes of processing time to complete, if the terrain maps need to be created. If a 

terrain map already exists for the selected domain, it is recalled, and processing time is reduced. 

Defining the burn project is the last requirement before receiving tabular reports or graphic display 

information. This requires 12 user inputs with various subforms involved. Multiple fires in one 

domain are allowed, but you have to edit the fire definition subform before completion. Upon 

satisfying the burn project definition requirements, a gridded map of Wyoming was drawn on the 

screen showing the defined domain and the major cities. If not satisfied with the current definition, 

the user has the option to delete the current burn project and start over again or accept it. It would 

seem more logical to initially set up the domain on the map rather than wait until the final 

verification to show it. 

6

 A newer version has fixed this omission from the manual (see footnote 1). 

26 
The graphics representation of the output data is a new and important feature for TSARS Plus.

CITPUFF (Ross and others 1987), the plume dispersion module of TSARS Plus, generates 

three-dimensional models of puff trajectories and dispersion by using Lagrangian puff and 

Gaussian dispersion techniques. On each applicable map or grid product, these key letters are 

seen: 

"F" (fire location) 

"R" (valid receptors) 

"H" (the point of highest concentration) 

After each graph is drawn on the screen, users have the option to toggle the print screen key 

to receive a printed copy (laser printers only). Three options for graphics exist: 

1. Concentrations on the Grid with Receptors. (Shows concentration isopleths and the 

legend informs users of contour interval (micrograms per cubic meter), the isopleths are 

overlaid on a grid) 

2. Display Contour Map. (Offers a choice of projects from the burn project inventory and gives 

a speedy plot of topography with overlay of named fire (F) and receptor (R) sites within that 

domain) 

3. Puffs on Terrain Contour. (Shows the contour map overlain by concentric puffs, which follow 

the prevailing wind trajectory and emulate lateral dispersion, where the cross (+) at the bottom 

of each circle represents the point concentration levels given in the tabular report at that time 

step) 

After completing the burn-project development, the maps are automatically created and 

displayed. Output data are saved in the database for future access. The first display is of the 

contour map of the domain, which takes about 30 to 60 seconds to draw. The next graph is 

the Concentration on the Grid with Receptors, followed by Puffs on Terrain Contour 

simulation, which took 5 to 10 minutes to compute and display.7 

The graphics provide good information. Depending on the default values assigned in the burn 

project, users can step through graphic pages for each time period selected. If 24-hour averages 

were selected, one of each map-type is generated. If 1-hour averages were used, users can 

view each time-step for the duration of the run. Use of the multiple time steps feature produced 

such halting screen redraws for both the Concentration on the Grid with Receptors and Puffs on 

Terrain Contour displays that there was an impression that the program had locked up, even 

though it was still working. The manual states that a 486 DX 50 MHZ will give optimal 

performance. Testing, however, emphasized that a Pentium or DX4 100 MHZ processor would 

be a better choice.

7 If 1-hour averaging is selected, the first-hour Puffs on Terrain Contour is displayed. If 

24-hour averaging is selected, the concentration contour is displayed for the first 24-hour 

period (Sestak and Riebau, see footnote 6). 

27 
When the message, "use Print Scrn to print," displays, the current graphics page is completely 

redrawn. If users press any key other than enter, carriage return, or Print Screen, the 

characters are typed on the screen over the graphics. It also was found that when in the Assign 

Met Station to Wind Field File menu, if users hit the ESC key instead of mousing to close, the 

current screen scrolls partially off the screen. This effectively locks up the program and 

keyboard. This same scenario happens in Output Puffs on Terrain Contour by hitting ESC 

instead of carriage return. 

The TSARS Plus package has many powerful features, and is set up to allow users to store and 

retrieve a great amount of scenario data for prescribed burning. The option for either tabular or 

graphic outputs is a large step towards easier interpretation of data. Although the sample files 

worked fine to become acquainted with the software, defining a new burn project was not as 

easy. Most sessions with this program resulted in unrecoverable errors. All errors encountered 

were major in the sense that after an initial warning message, any key press would bring the full 

error message and program termination. Heeding the instruction, "always exit program with 

File/Quit," users are unaware if all the files have been saved properly during the error-trapping 

event. The program does offer a utility to rebuild damaged database files and their indexes. At 

one point, even this function failed, making it necessary to reinstall the software. 

External weather data files cannot be imported into the program because the model developers 

have found no source readily accessible to field personnel and project managers. This means 

that the use of real-time weather products by the program is cumbersome. Instead, a set of 

data-entry forms exist in the Wind Field Setup /Assign Met Station Data option, under the 

Database menu, where users are responsible for hand-keying this information into the 

database. The program does not seem to facilitate quick changes in wind data, 9

 to play many 

"what-if" scenarios in a short time span. Users are forced to restructure multiple elements in the 

template system, namely meteorological stations and their data, and recalculate concentrations 

and wind-field generation to receive graphics or tabular report output. 

The program seems too geographically dependent and limited by the stringent latitude and 

longitude of program requirements for most template data. For each run, users must input the 

location of all meteorological, fire, and receptor sites before knowing whether or not the sites fit 

into the domain. Because TSARS Plus requires at least one upper air observation, 

surface-wind approximations improve with a greater number of surface observations, and 

receptor locations are crucial for each simulation, it would help to know a priori if the sites all fit 

into the domain or not. The program matches the domain with latitude and longitude locations 

automatically after all site locations are entered. This is a difficult task for users, because 

domains are defined by the latitude and longitude of one corner, then a size in kilometers. If 

the

8

 A newer version has fixed this error (Sestak and Riebau, see footnote 6). 

9

 Apparently it is possible to easily change most of the meteorological data, but how to 

do so is not intuitive (Sestak and Riebau, see footnote 2).

28 
sites do not fit into the domain, and users need them to fit, all must be reentered. In the 

current program flow, the process of constructing templates seems overly complex and 

can leave users wondering which piece of information is not correctly listing the latitude 

and longitude for the project. This results in a fair amount of backtracking to correct user 

errors instead of getting the results. 

Tolerances for location definitions of meteorological stations seem equally restrictive 

when, for example, the grid is misaligned. The manual makes no mention of tolerance for 

the reuse of existing terrain maps. Do these domain grids need to match precisely, or can 

they overlap a certain amount and still be reused? Also, if you assign a meteorological 

station with proper latitude and longitude, but a bogus elevation, what does this do to the 

validity of wind-field or burn-project definition? 

CALPUFF [version 3.0, 07/95]–CALPUFF is a multilayer, multispecies, nonsteadystate 

Gaussian puff dispersion model containing modules for complex terrain effects, overwater 

transport, coastal interactive effects, building downwash, wet and dry removal, and simple 

chemical transformation. Project development is being funded by regulatory agencies and 

industry in the United States and Australia. This program is capable of serious modeling 

for air transport of particulate matter over time and space, and it uses gridded domains 

with multiple vertical layers. 

Installation of the software offered no problems with a group created in Program Manager 

of Windows that contains CALPUFF and CALMET icons and a “help” icon for each. The 

help system gives an informative program overview, defines limits for any input variable, 

and offers detailed technical program details. Installation of this version of the CALPUFF 

group uses about 8 megabytes of disk space. 

Both CALMET and CALPUFF currently have Windows-VB input programs. The userinterface of CALPUFF has been developed to allow users an alternative project development environment to editing filename.INP - the run control file that controls all file 

input and output, modeled species, and terrain parameters. This is an ASCII text file with 

which users needs to become familiar. Both CALMET and CALPUFF exit to a DOS 

extender shell to execute their respective Fortran executable files. The user-interface 

goes one step further in trapping potential input errors by rule checking the current control 

file [?.INP] before running the Fortran executable files. This routine will display the errors 

in a table, which allows direct access to the input form and correction of the error. The 

software features good development and error trapping, and follows standard Windows 

conventions. 

CALMET is a diagnostic wind-file generator capable of micrometeorological modeling for 

overland and water boundary conditions, among other things. It also came with a 

Windows user-interface written in VB. CALMET needs several preprocessors that format 

various National Climate Data Center (NCDC) data (for example, CSUMM, TD3240, and 

MM4). The CALMET version 3.0 did not come with the six weather preprocessors that 

are listed in the CALMET program flow diagram.10 At this time, users of CALMET may 

need to create their own preprocessors for meteorological data not currently supported. 

10 Weather preprocessors should be on a newly available compact disk for 

CALPUFF (Scire, see text footnote 5). 

29 
CALPOST is included with CALPUFF and is a DOS-based executable.11 CALPOST is a 

required step to format output files so they can be exported to external graphics programs. It 

creates time-averaged concentrations and deposition fluxes predicted by CALPUFF. 

CALPOST also is capable of computing visibility impacts. A batch file is included, which 

allows users to assign the current calpost.INP file and input data (model.dat) as 

command-line trailers. References to CALPOST can be found in the user manual. 

The raw input file of EPM data for CALPUFF is Baemarb.dat (buoyant source emissions file 

with arbitrarily varying emissions). The manual states that an unnamed preprocessor is 

included with version 3.0 to prepare EPM output for CALPUFF. No version of EPM was 

included with the program. For many of the input files for CALPUFF, a sample data file is 

included in the header and variable description section of the manual. For others, such as 

Volem.dat and Baemarb.dat, no sample file is offered. Without a biomass source-strength 

module (for example, EPM) no results could be produced with CALPUFF for biomass burns. 

Another program is said to round out the CALPUFF suite. This is CALGRID, an Eulerian 

photochemical transport and dispersion model, which supplies subgrid analysis for 

complex terrain. Output format and file structure seem to be currently unassigned in the 

manual. CALGRID was not supplied with version 3.0. 

The manuals (one for each module), are extensive and, because of the complexity of the 

program, need to be used. They are more scientific reports, however, than "how-to" user 

manuals. It required over 2 hours of reading to become familiar with the features and layout of 

the program. Nowhere in the manual, or the onboard help, is there a quick and dirty 

explanation of how to jump into the program and obtain results. 

In short, CALPUFF is a program written by scientists for scientists that has not been 

developed for use by field people. The program expects a lot of background knowledge 

on the part of the end user. 

Although CALPUFF offers a rich set of features for regional air management, it seems to 

remain in the developmental stages. It also seems that each release of CALPUFF adds 

another finished segment of the entire package. Currently, the use of final output products is 

left to the imagination of the user. CALPOST does output data in a format suitable for import 

into other statistical or graphics packages for final interpretation.

11 A newer version of CALPOST has its own Windows interface (Scire, see 

text footnote 5). 

30 

*U.S. GOVERNMENT PRINTING OFFICE: 1997- 589-353 / 63004 REGION NO. 10 
The Forest Service of the U.S. Department of 

Agriculture is dedicated to the principle of multiple use 

management of the Nation's forest resources for 

sustained yields of wood, water, forage, wildlife, and 

recreation. Through forestry research, cooperation with 

the States and private forest owners, and management of 

the National Forests and National Grasslands, it strives–

as directed by Congress–to provide increasingly greater 

service to a growing Nation. 

The United States Department of Agriculture (USDA) prohibits 

discrimination in its programs on the basis of race, color, 

national origin, sex, religion, age, disability, political beliefs, and 

marital or familial status. (Not all prohibited bases apply to all 

programs.) Persons with disabilities who require alternative 

means of communication of program information (Braille, large 

print, audiotape, etc.) should contact the USDA Office of 

Communications at (202) 720-2791. 

To file a complaint, write the Secretary of Agriculture, U.S. 

Department of Agriculture, Washington, DC 20250, or call 

(800) 245-6340 (voice), or (202) 720-1127 (TDD). USDA is an 

equal employment opportunity employer. 

Pacific Northwest Research Station 

 333 S.W. First Avenue 

 P.O. Box 3890 

 Portland, Oregon 97208-3890