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WRAP TECHNICAL SUPPORT SYSTEM WEB SITE DESCRIPTION

November 16, 2009 draft

OVERVIEW

The Technical Support System (TSS) (http://vista.cira.colostate.edu/tss/) has been 

developed by the Western Regional Air Partnership (WRAP) to provide a single portal to 

technical data and analytical results prepared by WRAP Forums and Workgroups. The data, 

results, an methods displayed on the TSS are intended to support the air quality planning needs 

of western state and tribes, and will be maintained and updated to support both the 

implementation of regional haze plans and other Western air quality analysis and management 

needs. The concept for the TSS is based on the final recommendations of the Attribution of 

Haze Phase I project (http://wrapair.org/forums/aoh/ars1/report.html).

The primary purpose of the TSS is to provide key summary analytical results and 

methods documentation for the required technical elements of the Regional Haze Rule, to 

support the preparation, completion, evaluation, and implementation of the regional haze 

implementation plans to improve visibility in Class I areas. The TSS provides technical results 

prepared using a regional approach, including summaries and analyses of the comprehensive 

datasets used to identify the sources and regions contributing to regional haze in the Western 

Regional Air Partnership (WRAP) region. 

The secondary purpose of the TSS is to be the one-stop-shop for access, visualization, 

analysis, and retrieval of the technical data and regional analytical results prepared by WRAP 

Forums and Workgroups in support of regional haze planning in the West. The TSS specifically 

summarizes results and consolidates information about air quality monitoring, meteorological 

and receptor modeling data analyses, emissions inventories and models, and gridded air 

quality/visibility regional modeling simulations. These large and diverse data sets are integrated 

for application to air quality planning purposes by prioritizing and refining key information and 

results into explanatory tools.

The TSS integrates a number of different information resources, or data nodes, under one 

web-based umbrella. The data nodes currently supporting the TSS include:

Visibility Information Exchange Web System (VIEWS) – VIEWS is an online 

exchange of air quality data, research, and ideas designed to support the Regional 

Haze Rule enacted by the U.S. EPA to reduce regional haze and improve visibility in 

national parks and wilderness areas.

Causes of Haze Assessment (CoHA) – The CoHA web site is an online report that 

answers questions about the chemical components that cause regional haze, 

relationships of haze to meteorology, the emissions that cause haze, and the effects of 

previous and future emissions reductions on the worst and best visibility levels.

Emissions Data Management System (EDMS) – The WRAP EDMS is an emission 

inventory data warehouse and web-based application that provides a consistent 

approach to regional emissions tracking to meet the requirements for State 

Implementation Plan (SIP) and Tribal Implementation Plan (TIP) development and 

periodic review and updates.

Fire Emissions Tracking System (FETS) – The FETS is a database with a web 

interface for planned and unplanned fire events. Users can view fire data on-screen 
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with a mapping tool and query the database for downloads of data into model-ready 

formats and CSV or DBF formats.

WRAP Regional Modeling Center (RMC) – The WRAP RMC assists State and 

Tribal agencies in conducting regional haze analyses over the western U.S. by 

operating regional scale, three-dimensional air quality models that simulate the 

emission, transformation, and transport of pollutants and the effects on visibility in 

WRAP Class I Areas.

The value of the TSS is that it takes each of these separate data nodes and incorporates 

their key data sets, analysis results, and documentation. These key elements are presented in a 

straightforward, easily understandable manner. Planners and analysts requiring in-depth 

information beyond that summarized on the TSS can access the data nodes directly from the 

Projects page (http://vista.cira.colostate.edu/TSS/Projects/Default.aspx) on the TSS Home page.

The following sections describe the major TSS web pages and provide some insight into 

how to best apply the analytical tools available.

HOME PAGE

The TSS Home page is accessible at: http://vista.cira.colostate.edu/tss/. Navigation from 

this page includes the left-hand navigation bar (available from most of the TSS pages, and can be 

hidden if desired) and the buttons with yellow arrows in the center of the page. System log-in 

and user account options are readily accessible, though users are not required to log in. TSSrelated news items are also featured on the Home page. Figure 1 shows the layout of the Home 

page.

Figure 1. The TSS Home Page.

Navigation 

Buttons

Navigation 

Bar

Hide 

Navigation 

Bar

News and 

Events

Log-in and 

User 

Account 

Options

Navigation 

Buttons

Navigation 

Bar

Hide 

Navigation 

Bar

News and 

Events

Log-in and 

User 

Account 

Options
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RESOURCES PAGE

The Resources page is the gateway to the site’s analytical tools and methods 

documentation. From this page the user can choose to investigate the following topics:

Haze Planning – This page leads to a variety of data and analysis review tools 

designed to support RHR reasonable progress demonstrations. Detailed descriptions 

of these tools are presented in the following section. Methods documentation for 

these tools and analyses can be found on the specific data type pages as indicated in 

the following bullets.

Monitoring – This page leads to monitoring data review tools and descriptive 

documents, including:

A detailed overview of the IMPROVE monitoring network;

An overview of WRAP data substitutions methods use for sites not meeting RHR 

data completeness guidelines;

An overview of how natural conditions were estimated for use with the revised 

IMPROVE algorithm;

A key to mapping parameters across monitoring, modeling, and emissions 

disciplines; and

Related monitoring data links.

Emissions – This page leads to emissions data review tools and descriptive 

documents, including:

An overview of emissions inventory and processing activities;

Individual documents for each type of emissions inventory prepared for WRAP;

A key to mapping parameters across monitoring, modeling, and emissions 

disciplines; and

Related emissions data links.

Modeling – This page leads to modeling review tools and descriptive documents, 

including:

A detailed overview of WRAP’s air quality modeling;

An overview of WRAP’s meteorological back trajectory modeling;

A key to mapping parameters across monitoring, modeling, and emissions 

disciplines; and

Related modeling links.

Apportionment – This page leads to source apportionment analysis review tools and 

descriptive documents, including:

An overview of the PM Source Apportionment Technology (PSAT) air quality 

modeling technique used to trace Sulfur/SOx and Nitrate/NOx from source 

regions to Class I areas;

An overview of the Organic Aerosol Tracer technique used to distinguish 

between various types of organic aerosol modeled to arrive at Class I areas;

An overview of the Weighted Emissions Potential (WEP) technique, a qualitative 

analysis to investigate the potential for specific regional emissions to impact 

Class I areas; and

A key to mapping parameters across monitoring, modeling, and emissions 

disciplines.

Each of the documentation pages contains a link to the “Key to Monitoring-ModelingEmissions Mapping” support file (http://vista.cira.colostate.edu/tss/help/parameterkey.aspx). 

This file summarized the often complex relationships among real-world visibility-related 

parameters and parameters defined by the IMPROVE program, the CMAQ and CAMx models, 
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and WRAP emissions inventories. Specific parameter types, abbreviations, equations, and 

comments are presented. As an example, consider the following relationships among these 

disciplines for carbon species:

Organic Carbon (OC) is measured by IMPROVE, but not modeled or directly 

represented in emissions inventories.

Organic Mass (OM or OMC), which is the sum total of all primary and secondary 

organic compounds, is calculated by IMPROVE from the OC measurement. Both 

models contain terms for specific OM constituents. OM is not directly represented in 

emissions inventories.

Primary Organic Aerosol (POA), which represents only organic carbon compounds 

emitted directly as particulates, cannot be distinguished in the IMPROVE 

measurements. However, both the models and the emissions inventories account for 

this portion of the total OM.

Volatile Organic Compounds (VOC), which are emitted in gaseous form but can 

condense to form particulate organic compounds, also cannot be directly accounted 

for by IMPROVE. VOCs are tracked in the models and emissions inventories.

HAZE PLANNING PAGE – Reasonable Progress Demonstration

The Regional Haze Rule sets a 60 year timeline for states to improve visibility within 

mandatory Federal Class I areas from “baseline” (2000-04) levels to “natural conditions” by 

2064. States are required to show that “reasonable progress” is expected to be made toward this 

goal over the course of intermediary planning periods. Reasonable progress is defined both in 

terms of what can be measured and projected using current scientific understanding and, when 

reviewing controls for existing facilities, specific compliance-related statutory factors. These 

factors are not addressed by the TSS, but include:

Cost of compliance

Time necessary for compliance

Energy and non-air quality environmental impacts of compliance

Remaining useful life of any existing source subject to such requirements

Regional Haze Rule guidance documents outline methods for tracking progress 

(http://www.epa.gov/ttn/oarpg/t1/memoranda/rh_tpurhr_gd.pdf), calculating natural conditions 

(http://www.epa.gov/ttn/oarpg/t1/memoranda/rh_envcurhr_gd.pdf), and using model results to 

project future visibility impacts (http://www.epa.gov/ttn/scram/guidance/guide/final-03-pm-rhguidance.pdf). Using these guidance documents as a starting point, WRAP has developed a 

process that addresses the technical aspects of determining reasonable progress. This process is 

supported by several documents which can be found on the Planning Information Exchange page 

(http://vista.cira.colostate.edu/TSS/Planning/InformationExchange.aspx).

RHR guidance requires reasonable progress to be tracked using the Haze Index 

(deciviews), which is determined as a logarithmic transformation of the sum of all light 

extinction terms in the IMPROVE light extinction algorithm. This method does not provide 

information regarding the relative contributions of individual species’ extinction to overall 

visibility. In addition, some species (sulfate and nitrate) originate from largely anthropogenic 

sources, while others originate from a mixture of both anthropogenic and natural sources. 

Therefore, WRAP adopted the additional method of tracking individual species’ extinction 

contributions in a manner similar to that outlined in RHR guidance for total deciview.

The major steps in WRAP’s recommended technical analyses for reasonable progress 

demonstration that are supported by the TSS Haze Planning tools include the following for each 

Class I area:
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Determine Baseline (2000-04) Visibility Conditions (deciviews and species’ 

extinction) using the revised IMPROVE algorithm, following RHR guidance to select 

the 20% worst and best visibility days, and using WRAP-approved substituted data 

when appropriate.

Determine Natural Conditions (deciviews and species’ extinction), based on the 

alternate method developed specifically for the revised IMPROVE algorithm.

Determine the Glide Slope between Baseline and Natural Conditions (deciviews and 

species’ extinction), and identify the glide slope value in 2018.

Project 2018 visibility using relative change between Baseline and 2018 modeling 

results (for deciviews and species’ extinction). (WRAP defined three methods to 

calculate visibility projections, the EPA default method and two alternate methods.)

Compare the 2018 projected values to the 2018 glide slope values. The deciview 

comparison is required by the RHR. The species comparisons provide information on 

the degree to which progress is expected to be made for individual pollutants. This 

progress is closely tied to whether emissions sources responsible for the pollutants are 

anthropogenic or natural.

Review the change in emissions from the Baseline to the 2018 inventories. This 

can be done on a regional, state, and county level. Specific analysis requirements are 

determined by the nature of the visibility impacts at and the location of the Class I 

area.

Review the source region contributions of modeled pollutants to Class I areas. 

This analysis should facilitate conversations between states where a shared impact on 

visibility exists. This analysis also identifies international source contributions 

beyond a state’s jurisdiction. There are two methods for this review:

The RMC performed the PSAT analysis, which tracked emissions responsible 

for sulfate and nitrate aerosols from source regions (WRAP states, Pacific 

offshore, Canada, Mexico, CENRAP, Eastern U.S., and boundary conditions) to 

Class I areas. This is the most reliable attribution method performed on WRAP

regional haze data.

The second method is the WEP analysis, which combined emissions densities 

with back trajectory residence times to evaluate the potential for emissions to 

impact Class I areas. This method did not model atmospheric chemistry or 

deposition, so its results should be interpreted qualitatively.

HAZE PLANNING PAGE – Data Review Tools

The Haze Planning page integrates all of WRAP’s major haze-related data sets and 

provides review tools designed to support a reasonable progress demonstration. The following 

subsections describe how to use the tools and provide help in interpreting results.

Important note: Some WRAP IMPROVE monitoring locations did not collect sufficient 

data to achieve Regional Haze Rule data completeness requirements or to fully populate the 

selected modeling year, 2002. For the purpose of addressing regional haze, data substitutions 

were performed for these sites. All Haze Planning data review tools use these substituted data 

sets, which are different than the standard IMPROVE data sets found on the VIEWS web site. 
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For more information on the substituted data sets see “WRAP Data Substitution Methods” 

(http://vista.cira.colostate.edu/docs/wrap/Monitoring/WRAP_Data_Substitution_Methods_April

_2007.doc).

Site Selection

Upon entering the Haze Planning page, the user is presented with a map showing the 

WRAP region, the WRAP Federal Class I areas, and the locations of IMPROVE monitoring 

sites. All currently operating or historically significant IMPROVE sites are available for 

selection, but not all tools are populated with data from outside the WRAP region. Figure 2 is 

annotated to identify key items and options on the Site Map. The controls along the top of the 

map are used to change the map view or select regions for analysis. Tool tips, associated with 

some of the map controls, appear on the screen by hovering over the control icons. The map 

controls include:

Map Mode tools – These controls include zoom and center options for the map.

When zoomed in sufficiently, site, Class I area, and tribal names become visible.

Select tools – These controls allow for selection of single site or entire state (Select 

Object tool), multiple sites (Select Box tool), and clearing a previous selection (Clear 

Selection tool).

Regional Views – Various pre-defined zoomed views are available. The default view 

is WRAP.

Tribal Lands – WRAP tribal lands can be added to the map. Pre-defined zoomed 

views are available for selected tribes. WRAP tribal lands have been associated with 

the most representative IMPROVE monitors for analysis on the TSS.

Monitoring sites can also be selected from the Site List. The Site List is hidden by 

default and must be opened to be used. Figure 3 is annotated to identify key options available. 

Multiple sites can be selected, and the list can be sorted by any of the headings. For example, 

clicking on the “State” heading sorts the sites by state.

Tool Selection

Below the Site Map and Site List are four (4) buttons, each of which opens a series of 

tools. Figure 4 shows these choices. Clicking on the “Class I Area Summary Table” opens a 

tool to generate a summary table populated with key Class I area results for demonstrating 

reasonable progress. Figure 5 shows the tool options associated with the “Monitoring” button. 

Clicking on the “Emissions and Source Apportionment” and “Modeling” buttons reveals tool 

options for those data sets.

The many options listed in Figure 5 represent only two distinct tools: a Time Series tool 

and a Glide Slope tool. Within these tools the user can select many options for display. 

However, since the Regional Haze Rule and WRAP’s method for demonstrating reasonable 

progress requires very specific choices, these choices have been pre-selected as indicated in this 

list.
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Figure 2. Haze Planning page site selection map.

Map View 

Options Zoom Controls

IMPROVE 

Monitoring 

Locations 

(WRAP Sites 

in Yellow)

Class I Areas 

(green)

Site Selection 

Options

Description of 

Selected 

Site(s)

Map Controls

Site Selection 

Help

Map View 

Options Zoom Controls

IMPROVE 

Monitoring 

Locations 

(WRAP Sites 

in Yellow)

Class I Areas 

(green)

Site Selection 

Options

Description of 

Selected 

Site(s)

Map Controls

Site Selection 

Help
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Figure 3. Haze Planning page site selection list.

Figure 4. Tool selection panel on the Haze Planning page.

Click on one 

or more sites 

to select

Click on any 

heading to 

sort

Review site 

locations 

and 

monitoring 

periods

Site list is 

hidden upon 

entering the 

Haze 

Planning 

page

Click on one 

or more sites 

to select

Click on any 

heading to 

sort

Review site 

locations 

and 

monitoring 

periods

Site list is 

hidden upon 

entering the 

Haze 

Planning 

page

Click to review 

Monitoring data

Click to review 

Modeling data

Click to review 

Emissions data and 

Source Apportionment 

results

Click to create a 

Class I Area 

Summary 

Table, 

containing key 

Class I area 

results

Click to review 

Monitoring data

Click to review 

Modeling data

Click to review 

Emissions data and 

Source Apportionment 

results

Click to create a 

Class I Area 

Summary 

Table, 

containing key 

Class I area 

results
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Figure 5. Monitoring data tools. Clicking on the “Emissions and Source Apportionment” and 

“Modeling” buttons reveals tool options for those data sets.

Select Time Series

or Glide Slope tools

Select Worst

or Best days

Select results for 

Deciview, Total 

Extinction or Species 

Extinction

Click to 

reveal tool 

selections

Select Time Series

or Glide Slope tools

Select Worst

or Best days

Select results for 

Deciview, Total 

Extinction or Species 

Extinction

Click to 

reveal tool 

selections
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CLASS I AREA SUMMARY TABLE

The Class I Area Summary Table calculates metrics to support regional haze analysis by 

species, total light extinction, and deciview. The results that are presented with this tool are 

derived from many of the other Haze Planning tools. Note that only one table for one Class I 

Area can be generated at a time. Attempting to generate tables for multiple sites at once will 

result in an error.

The Class I Area Summary Table tool can be found by clicking on the “Class I Area 

Summary Table” button on the Haze Planning page. Operations for the Control Panel selection 

boxes are shown in Figure 6 and described below:

Selection of Days – This option allows the user to select either the Worst or Best 

20% IMPROVE days.

Scenario – This option allows the user to select among pre-defined pairs of 

emissions/modeling scenarios.

RRF Calculation Method – This option allows the user to select among WRAP’s 

three methods for calculating relative response factors (RRFs). More information 

about this choice can be found under the “MODELING: Visibility Projections Tool” 

description below.

Create Table – Once all selections have been made, click this button to generate the 

summary table. It will generally take about 30 seconds to generate the table.

Figure 7 presents an annotated header for the Class I Area Summary Table. The results

in the first three columns are taken directly from the Visibility Projections tool (and are also 

available in the Glide Slope tool). The results in the fourth column are also taken from the 

Visibility Projections tool, and depend on the selection of Scenario and RRF Calculation 

Method. The results in the fifth column are calculated from information available in the 

Emissions Review tool, and depend on the selection of Scenario. The results in the sixth and 

seventh columns are calculated from information available in the Weighted Emissions Potential 

(WEP) tool. The only difference between these results is that the calculation for the seventh 

column excludes the following categories of (predominantly) natural emissions sources: Natural 

Fires, Biogenic, and Wind Blown Dust. Note that all WEP results are based on the “plan02d & 

prp18a” scenario pair.

The tabular display cannot be altered beyond the selections described above. It can be 

copied and pasted into spreadsheet software such as Microsoft Excel.
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Figure 6. Class I Area Summary Table. This tool creates a summary of regional haze-related 

information stored on the TSS.

Click 

for 

Help

Tool Control Panel

Options include:

1. Selection of Days

2. Scenario

3. RRF Calculation 

Method

Click here to 

create the table

Click 

for 

Help

Tool Control Panel

Options include:

1. Selection of Days

2. Scenario

3. RRF Calculation 

Method

Click here to 

create the table
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Figure 7. Class I Area Summary Table. Annotated header for the Class I Area Summary Table.
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MONITORING: Time Series Tool

The Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring 

program reports speciated PM data and associated estimates of light extinction. IMPROVE is a 

nation-wide network which began in 1988 and expanded significantly in 2000 in response to the 

EPA’s Regional Haze Rule. The Regional Haze Rule specifically requires data from this 

program to be used by states and tribes to track progress in reducing haze. Further information 

regarding the IMPROVE program and related monitoring data activities can be found under the 

Monitoring Methods section (http://vista.cira.colostate.edu/TSS/Results/Monitoring.aspx).

The Time Series tool can be found by clicking on the “Monitoring” button on the Haze 

Planning page. The purpose of the Time Series tool is to allow the user to review and investigate 

IMPROVE data based on specific temporal selections made via the tool Control Panel. Options 

for the Control Panel selection boxes are shown in Figure 6 and described below:

Parameter Group – These options select predetermined groups of parameters. The 

Mass selection automatically selects all major mass components from the Parameter

list (below) and graphically displays in units of μg/m3. The Light Extinction 

selection selects all major extinction components and graphically displays in units of 

Mm-1. Both of these options are commonly used to display temporal and contribution 

changes in all species in one graphic.

Parameter – This option allows the user to select one or more extinction, deciview, 

or mass parameters to display. All parameters selected will display as a stacked bar 

chart or line graph, so it is possible to select non-compatible or meaningless 

combinations (e.g., Total Extinction and Deciview – both are measured in different 

units). The user must be careful to select parameter combinations that provide 

meaningful information.

IMPROVE Algorithm – This option allows the user to determine how light 

extinction is calculated from measured mass parameters. The user can select the 

original or revised IMPROVE algorithm. The WRAP recommendation is for states to 

use the revised algorithm; therefore this selection is always the default, no matter 

what tool is chosen. Due to differences in how species are handled between 

algorithms, this choice can affect the selection of worst and best days. This generally 

has a small, but often unexpected effect on resulting averages.

Year – This option allows the user to select one or more years to display in the range 

1988 to the most recent year for which data are available. The baseline period (2000-

04) is the default. Longer timelines provide insight into historical trends.

Selection of Days – This option allows the user to select which set of days to display 

(if Daily is selected in the Averaging box) or which days to include in a displayed 

average (if Monthly or Annual is selected in the Averaging box). The Worst or Best 

20% IMPROVE days are allowable only for those years which have met the RHR 

data completeness requirements. The IMPROVE Sampled option uses all available 

IMPROVE data for the time periods selected. This choice should be used with care 

as any averages based on all collected data have no regulatory significance and may 

be misleading for periods of poor data capture.

Averaging – This option allows the user to select daily, monthly, and annual 

averaging periods for display.

Quarter – This option allows the user to select one or more specific quarters. 

Display of all quarters is the default.
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Chart Type – This option allow the user to select between a Timeline, which plots 

each parameter as in independent line graph, and Bar Chart, which plots single 

parameters as a bar and multiple parameters as a stacked bar.

Figure 9 presents several commonly used combinations of Control Panel selections for 

quick reference. Many of these selection boxes appear in other data review tools and perform 

the same functions described here.

The graphic displays cannot be altered beyond the selections described above. They can 

be saved or copied by right-clicking and making the appropriate selection. The data table below 

the graphic can be copied and pasted into spreadsheet software such as Microsoft Excel.

Figure 8. Monitoring: Time Series Tool. The pre-selected options for this tool were based on 

the choice of “Deciview Time Series.”

Tool Control Panel

Note the options

pre-selected include:

1. Worst Days

2. Baseline Years

3. Deciview

Data table represents what 

is displayed on the chart

Chart is created based on 

Control Panel selections

Click 

for 

Help

Tool Control Panel

Note the options

pre-selected include:

1. Worst Days

2. Baseline Years

3. Deciview

Data table represents what 

is displayed on the chart

Chart is created based on 

Control Panel selections

Click 

for 

Help
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Monitoring Time Series Graphical Displays Control Panel Selections

Annual Baseline Species Extinction, Worst Days

Daily Baseline Species Extinction, all IMPROVE Days

Historical Timeline of Annual Best Days

Individual Worst Days for 2002

Historical Contribution Timelines of Top 3 Species

Figure 9. Monitoring: Time Series Tool. Common graphical outputs and associated Control 

Panel selections.
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MONITORING: Glide Slope Tool

IMPROVE data are used to determine baseline visibility conditions, to estimate natural 

visibility conditions, and to calculate the RHR glide slope between baseline and natural

conditions.

The Glide Slope tool can be found by clicking on the “Monitoring” button on the Haze 

Planning page. The purpose of the Glide Slope tool is to allow the user to review the required 

RHR deciview glide slope and optional individual species extinction glide slopes. All results are 

presented based on extinction/deciview calculations using the revised IMPROVE algorithm. 

Extinction glide slopes are not defined in the RHR guidance, so their inclusion here is to support 

demonstrations of reasonable progress as defined by WRAP protocol. Options for the Control 

Panel selection boxes are shown in Figure 10 and described below:

Parameter Group – These options select predetermined groups of parameters, as 

described in the “MONITORING: Time Series Tool.”

Parameter – This option allows the user to select one or more extinction, deciview, 

or mass parameters to display. If parameters with different units are selected 

together, a second y-axis will appear on the left side of the graph.

Selection of Days – This option allows the user to select between the Worst and Best 

days, based on collected IMPROVE data. Note that there is no IMPROVE Sampled 

option as in the “MONITORING: Time Series Tool.” The Regional Haze Rule does 

not require states to calculate a glide slope for the Best days, so only the baseline and 

natural conditions values are displayed when the Best days option is selected.

Annual Data – This option allows the user to select individual annual averages to 

display on the chart, either to provide an understanding of the inter-annual variability 

during the baseline period or to track annual progress beyond the baseline period.

The graphic displays cannot be altered beyond the selections described above. They can 

be saved or copied by right-clicking and making the appropriate selection. The data table below 

the graphic can be copied and pasted into spreadsheet software such as Microsoft Excel.
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Figure 10. Monitoring: Glide Slope Tool. Glide slopes for Nitrate, Sulfate, and Organic Mass 

Extinction are shown.

Tool Control Panel

Note the options

selected include:

1. Baseline Years Data to 

show inter-annual variability

2. NO3, SO4, OMC species 

extinction

Species Glide 

Slopes

Click 

for 

Help

Baseline Average and 

Annual Extinction Values

Estimated Natural 

Conditions

Data table represents what 

is displayed on the chart

Tool Control Panel

Note the options

selected include:

1. Baseline Years Data to 

show inter-annual variability

2. NO3, SO4, OMC species 

extinction

Species Glide 

Slopes

Click 

for 

Help

Baseline Average and 

Annual Extinction Values

Estimated Natural 

Conditions

Data table represents what 

is displayed on the chart
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EMISSIONS & SOURCE APPORTIONMENT: SOx/NOx Tracer Tool

WRAP’s Regional Modeling Center performed a source apportionment analysis using the 

CAMx air quality model and the PSAT (PM Source Apportionment Technology) tool. Results 

from this analysis provide information regarding which source regions and source categories are 

responsible for particulate aerosol modeled at a receptor. Due to resource limitations, this 

analysis was restricted to SOx and NOx emissions resulting in sulfate and nitrate mass. The 

results do not directly represent actual sulfate and nitrate measurements, nor can they accurately 

be transformed into extinction values. Therefore, these results should be viewed in relative terms 

among source regions and between emissions scenarios. Further information regarding the 

PSAT modeling technique can be found under the Source Apportionment Methods section 

(http://vista.cira.colostate.edu/TSS/Results/SA.aspx).

The SOx/NOx Tracer tool can be found by clicking on the “Emissions and Source 

Apportionment” button on the Haze Planning page. The purpose of the SOx/NOx Tracer tool is 

to allow the user to investigate modeled attribution results for sulfate and nitrate mass at Class I 

areas. Options for the Control Panel selection boxes ( Figure 11) are described below:

Parameter – This option allows the user to select either Nitrate/NOx or Sulfate/SOx 

results to display. (The CAMx/PSAT methodology was not used to trace other 

pollutants due to resource constraints.)

Emissions Scenario – This option allows the user to select one or more emissions 

scenarios. (The CAMx/PSAT methodology was applied only to the Plan02c and 

Base18b scenarios).

Source Categories – This option allows the user to select one or more emissions 

source categories. Display of all categories requires for the source region “Outside 

Domain” to show up on the bar chart.

Natural Fires and Biogenics (WRAP) – The sum of WRAP fire emissions 

categorized as natural and biogenic emissions

Anthropogenic Fires (WRAP) – All man-made WRAP fire emissions

Mobile – All on- and off-road mobile source emissions

Area – All area source emissions

Point – All point source emissions

Source Regions – This option allows the user to select one or more WRAP states or 

other defined areas as source regions, including an “Outside Domain” category which 

comprises the model’s initial and boundary conditions.

Selection of Days – This option allows the user to select which set of model days to 

display or which days to include in a displayed average. The Worst or Best 20% 

IMPROVE days options select modeled days identical with the 2002 IMPROVE 

Worst and Best days. The IMPROVE Sampled option uses all modeled days that 

correspond to available IMPROVE days in 2002. The All Days option uses all 365 

modeled days for 2002.

Averaging – This option allows the user to select daily, monthly, and annual 

averaging periods for display. Daily and monthly selections should be used only 

when single Source Regions have been selected.

Quarter – This option allows the user to select one or more specific quarters.

The pie charts display relative regional contributions to total annual modeled sulfate or 

nitrate mass. The WRAP contribution is separated from the rest of the pie for easy identification. 
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The remaining pie slices include those regions listed in the Source Region box plus the sum of 

the model’s Initial and Boundary Conditions, termed “Outside Domain.” The total modeled 

mass traced to the Class I area is displayed below each pie. The pie charts will change based on 

selections in the Parameter, Emissions Scenario and Selection of Days boxes. They will not 

change based on selections in the Source Category or Source Region boxes.

The bar chart displays source region and source category contributions of sulfate or 

nitrate mass. Display of all source regions is the default. Once all regions’ contributions have 

been reviewed, those with significant contributions can be selected individually and reviewed 

using the Monthly or Daily Averaging selections. This will identify any temporal patterns in a 

state’s contributions.

Figure 12 presents several commonly used combinations of Control Panel selections for 

quick reference. The graphic displays cannot be altered beyond the selections described above. 

They can be saved or copied by right-clicking and making the appropriate selection. The data 

table below the graphic can be copied and pasted into spreadsheet software such as Microsoft 

Excel.

Figure 11. Emissions & Source Apportionment: SOx/NOx Tracer Tool. This tool displays 

regional and state contributions to sulfate or nitrate mass. Tool Control Panel

Note the options

selected include:

1. Baseline and 2018 

emissions scenarios

2. All WRAP states and other 

source regions

3. All source categories

Click 

for 

Help

Regional contributions to 

modeled sulfate mass at 

selected Class I area

(WRAP slice separated)

WRAP states’ 

contributions by 

source category 

(Note change 

between paired 

emissions 

scenario bars)

Tool Control Panel

Note the options

selected include:

1. Baseline and 2018 

emissions scenarios

2. All WRAP states and other 

source regions

3. All source categories

Click 

for 

Help

Regional contributions to 

modeled sulfate mass at 

selected Class I area

(WRAP slice separated)

WRAP states’ 

contributions by 

source category 

(Note change 

between paired 

emissions 

scenario bars)
20

Source Apportionment Graphical Displays Control Panel Selections

Annual Contribution of Nitrate, Best Days

Single State, Daily Contribution of Sulfate, Worst Days

Single State, Daily Contribution, All Model Days

Figure 12. Emissions & Source Apportionment: SOx/NOx Tracer Tool. Common graphical 

outputs and associated Control Panel selections.
21

EMISSIONS & SOURCE APPORTIONMENT: Weighted Emissions Potential Tool

The Weighted Emissions Potential (WEP) analysis was developed as a screening tool for 

states to decide which source regions have the potential to contribute to haze formation at 

specific Class I areas, based on both the Baseline (Plan02d) and 2018 (PRP18) emissions 

inventories. Unlike the SOx/NOx Tracer analysis, this method does not account for chemistry 

and removal processes. Instead, the WEP analysis relies on an integration of gridded emissions 

data, meteorological back trajectory residence time data, a one-over-distance factor to 

approximate deposition, and a normalization of the final results. Residence time over an area is 

indicative of general flow patterns, but does not necessarily imply the area contributed 

significantly to haze at a given receptor. Therefore, users are cautioned to view the WEP 

analysis as one piece of a larger, more comprehensive weight of evidence analysis. Further 

information regarding the WEP analysis method can be found under the Source Apportionment 

Methods section (http://vista.cira.colostate.edu/TSS/Results/SA.aspx).

The WEP tool can be found by clicking on the “Emissions and Source Apportionment” 

button on the Haze Planning page. Options for the Control Panel selection boxes are shown in 

Figure 13 and described below:

Parameter – This option allows the user to select results for one parameter at a time. 

The gridded emissions used for this analysis represent annual totals. Note that the 

Primary Organic Aerosol parameter represents organic carbon compounds emitted 

directly as particulates, but not secondary organics which condense from a gaseous 

state after being emitted.

Selection of Days – This option allows the user to select meteorological back 

trajectory residence time fields based on the Worst and Best IMPROVE days.

Source Categories – This option allows the user to select one or more emissions 

source categories. Display of all categories is the default.

Source Regions – This option allows the user to select one or more source regions, 

including: individual WRAP states, Pacific Offshore, CENRAP, Eastern U.S., 

Canada, and Mexico. Display of all regions is the default.

The WEP bar charts display normalized (unitless), residence time- and distance-weighted 

annual emissions value, by emissions source region. These WEP results are reminiscent of the 

SOx/NOx Tracer tool results. However, the WEP results are considered less rigorous and should 

be used only as a screening tool to identify regions with the potential to impact Class I areas. 

The 2018 results are further normalized by the Baseline results so that actual changes in 

weighted emissions between scenarios is evident.

The WEP map matrix contains 7 individual maps. The left column contains maps of the 

emissions inventories, with all sources combined. The central single map depicts the Worst or 

Best days residence times for the baseline period, determined using the revised IMPROVE 

algorithm. The same residence time field is used with all emissions scenarios. The right column

contains maps of the normalized, weighted emissions. Geographical regions and individual grid 

cells with significant potential to impact the selected Class I area are easily distinguished in these 

maps. Each map can be enlarged by clicking on it.

The graphic displays cannot be altered beyond the selections described above. They can 

be saved or copied by right-clicking and making the appropriate selection. The data table below 

the bar chart can be copied and pasted into spreadsheet software such as Microsoft Excel.
22

Figure 13. Emissions & Source Apportionment: Weighted Emissions Potential Tool. Annual 

emissions inventories were weighted by back trajectory residence time and distance, and then

normalized. Results indicate geographic regions with the potential to impact selected Class I 

areas. Click 

for 

Help

Normalized regional contributions to 

residence time- and distance-weighted 

emissions

Tool Control Panel

Parameters include major emissions categories

Source Categories/Regions selections affect 

what is displayed on the bar chart

Click on any map to 

enlarge in a separate 

window

Resultant WEP map can 

be used as a screening 

tool to identify potentially 

important source regions

Data table option

Gridded emissions maps

Gridded back trajectory 

residence times for 

Baseline (2000-04) 

Worst (or Best) days

Click 

for 

Help

Normalized regional contributions to 

residence time- and distance-weighted 

emissions

Tool Control Panel

Parameters include major emissions categories

Source Categories/Regions selections affect 

what is displayed on the bar chart

Click on any map to 

enlarge in a separate 

window

Resultant WEP map can 

be used as a screening 

tool to identify potentially 

important source regions

Data table option

Gridded emissions maps

Gridded back trajectory 

residence times for 

Baseline (2000-04) 

Worst (or Best) days
23

EMISSIONS & SOURCE APPORTIONMENT: Organic Aerosol Tracer Tool

The CMAQ model results were analyzed to identify organic carbon aerosol source 

contributions as originating in one of three categories:

Primary organics (anthropogenic and biogenic sources), resulting from direct organic 

aerosol emissions;

Anthropogenic secondary organics, resulting from aromatic VOCs, such as xylene, 

toluene, and cresols; and

Biogenic secondary organics, resulting from biogenic VOCs, such as terpenes.

This analysis did not include identification of emissions source regions or detailed source 

category information. Further information regarding the Organic Aerosol Tracer technique can 

be found under the Source Apportionment Methods section 

(http://vista.cira.colostate.edu/TSS/Results/SA.aspx).

The Organic Aerosol Tracer tool can be found by clicking on the “Emissions and Source 

Apportionment” button on the Haze Planning page. The purpose of the tool is to allow the user 

to investigate the contribution of primary and secondary anthropogenic and biogenic sources on 

modeled organic carbon at Class I areas. Options for the Control Panel selection boxes are 

shown in Figure 14 and described below:

Parameter – This option allows the user to select among the three types of organic 

aerosol. Display of all types is the default.

Emissions Scenario – This option allows the user to select one or more emissions 

scenarios.

Selection of Days – This option allows the user to select which set of model days to 

display or which days to include in a displayed average. The Worst or Best 20% 

IMPROVE days options select modeled days identical with the 2002 IMPROVE 

Worst and Best days. The IMPROVE Sampled option uses all modeled days that 

correspond to available IMPROVE days in 2002. The All Days option uses all 365 

modeled days for 2002. Aerosol loadings from large fire events can clog IMPROVE 

filters and result in lost data. It is advisable to review results using both the All Days 

option and the IMPROVE Sampled option to understand if significant events captured 

by the model are missed by the selection of IMPROVE Sample days only.

Averaging – This option allows the user to select daily, monthly, and annual 

averaging periods for display.

Quarter – This option allows the user to select one or more specific quarters. 

Display of all quarters is the default.

The bar chart displays modeled contributions to organic aerosol. Individual organic 

aerosol parameter types and specific time aggregations and periods can be selected for a detailed 

review of temporal patterns. Figure 15 illustrates how the tool can be used to see the modeled 

change in organic aerosol contribution between the Baseline and 2018 Base Case scenarios.

The graphic displays cannot be altered beyond the selections described above. They can 

be saved or copied by right-clicking and making the appropriate selection. The data table below 

the graphic can be copied and pasted into spreadsheet software such as Microsoft Excel.
24

Figure 14. Emissions & Source Apportionment: Organic Aerosol Tracer Tool. This tool 

identifies organic carbon source type contributions as: 1) primary organics (anthropogenic and 

biogenic); 2) anthropogenic secondary organics; and 3) biogenic secondary organics. The results 

do not include emissions source regions or detailed source category information.

Figure 15. Emissions & Source Apportionment: Organic Aerosol Tracer Tool. Monthly results 

for the Baseline and 2018 emissions scenarios are shown here. Each pair of bars illustrates the 

modeled change in organic aerosol.

Tool Control Panel

Note the options include:

1. Source Type of Organic Aerosol

2. Emissions Scenario

Click 

for 

Help

Compare source-type contribution 

of organic aerosol for daily, monthly 

or annual averaging periods

Data table 

represents what 

is displayed on 

the chart

Tool Control Panel

Note the options include:

1. Source Type of Organic Aerosol

2. Emissions Scenario

Click 

for 

Help

Compare source-type contribution 

of organic aerosol for daily, monthly 

or annual averaging periods

Data table 

represents what 

is displayed on 

the chart
25

EMISSIONS & SOURCE APPORTIONMENT: Emissions Review Tool

The WRAP developed a set of comprehensive emissions inventories for 2002, the 

baseline period (2000-04), and 2018. Further information regarding the WRAP emissions 

inventory work can be found under the Modeling Methods section 

(http://vista.cira.colostate.edu/TSS/Results/Emissions.aspx).

The Emissions Review tool can be found by clicking on the “Emissions & Source 

Apportionment” button on the Haze Planning page. Data are based on the SMOKE emissions 

modeling system for each pollutant by source category, emissions scenario, and regional, state, 

and county designations. These emissions inventories are similar but not identical to inventories 

available on WRAP’s Emissions Data Management System (EDMS). (For general EDMS 

information, go to http://www.wrapedms.org/. For access to detailed EDMS inventories 

available on the TSS, go to http://vista.cira.colostate.edu/TSS/EDMS.ASPX or 

http://vista.cira.colostate.edu/TSS/EDMS_map.ASPX.) Options for the tool’s Control Panel 

selection boxes are shown in Figure 16 and described below.

Parameter – This option allows the user to select summaries by pollutant. The 

regional emissions represent annual totals. Note that the “gas and particulate” option 

for Sulfur Oxides and Nitrogen Oxides provides the complete SMOKE emissions 

outputs, but the Sulfur Dioxide and Nitrogen Oxides (gas) selections provide gaseous 

emissions only, which are comparable to information available in Eastern Research 

Group’s (ERG’s) pivot tables.

Emissions Scenario – This option allows the user to select single or pre-defined pairs 

of scenarios. Additionally, the user can select either SMOKE-processed, gridded 

emissions data (from the TSS) or native emissions inventories (from the EDMS) as 

the data source type. The user can also select both to compare SMOKE-processed 

and native inventories.

Source Categories – This option allows the user to select one or more emissions 

source categories.

Region – This option allows the user to select one or more states/regions for which 

the emissions data are presented. The only exception to regional sums is the offshore category; Pacific and Atlantic region emissions must be viewed separately. It is 

important to note that the international inventories used by WRAP do not always 

present data from different scenarios in a consistent manner. However, the Emissions 

Review tool accurately presents what was used in WRAP’s regional modeling efforts.

County – If a single State or Province is selected, then individual counties or districts 

will be presented for selection in the County selection box. See Figure 17 for an 

example.

The graphic displays cannot be altered beyond the selections described above. They can 

be saved or copied by right-clicking and making the appropriate selection. The data table below 

the graphic can be copied and pasted into spreadsheet software such as Microsoft Excel.
26

Figure 16. Emissions & Source Apportionment: Emissions Review Tool. This tool allows the 

user to review annual emissions processed through SMOKE for WRAP’s modeling efforts.

Select individual 

states or entire 

regions

Select 

single 

parameters 

and 

multiple 

source 

categories

Note the options include 

displaying model data 

from single or paired 

emissions scenarios

This graph compares 

the Baseline and 2018 

NOx emissions for all WRAP states

Click here to view the data table

Select type of 

emissions data: 

1. SMOKEprocessed; 

2. Native 

inventory; 

3. Both

Select individual 

states or entire 

regions

Select 

single 

parameters 

and 

multiple 

source 

categories

Note the options include 

displaying model data 

from single or paired 

emissions scenarios

This graph compares 

the Baseline and 2018 

NOx emissions for all WRAP states

Click here to view the data table

Select type of 

emissions data: 

1. SMOKEprocessed; 

2. Native 

inventory; 

3. Both
27

Figure 17. Emissions & Source Apportionment: Emissions Review Tool. When a single state 

or province is selected, the County box will populate with counties or districts.

This graph compares 

the Baseline and 2018 

NOx emissions for all 

Arizona counties

The County box will 

populate only when a 

single state is selected

This graph compares 

the Baseline and 2018 

NOx emissions for all 

Arizona counties

The County box will 

populate only when a 

single state is selected
28

MODELING: Model Performance Tool

The WRAP developed a set of comprehensive emissions inventories for 2002, the 

baseline period (2000-04), and 2018. These inventories were used to model visibility impacts for 

the same time periods. Further information regarding the WRAP modeling techniques can be 

found under the Modeling Methods section 

(http://vista.cira.colostate.edu/TSS/Results/Modeling.aspx).

The Model Performance tool can be found by clicking on the “Modeling” button on the 

Haze Planning page. The purpose of the Model Performance tool is to allow the user to visually

gauge model performance on a site-by-site basis by comparing the 2002 modeling results 

(Base02) with the IMPROVE monitoring data collected in 2002. Model performance varies by 

species and sometimes by time of year, so it is important for users to review these results in more 

than one way. Detailed model performance reviews can be found on the RMC web site 

(http://pah.cert.ucr.edu/aqm/308/). Options for the tool’s Control Panel selection boxes are 

shown in Figure 18 and described below:

Parameter – This option allows the user to select one or more mass parameters to 

display. There is no option to select extinction parameters because model 

performance is best reviewed based on mass. (Note that the model results do not 

include sea salt as a parameter.)

IMPROVE Algorithm – The user can select the original or revised IMPROVE 

algorithm. The WRAP recommendation is for states to use the revised algorithm; 

therefore this selection is the default. Due to differences in how species are handled

between algorithms, this choice can affect the selection of worst and best days. This 

generally has a small, but often unexpected effect on resulting averages.

Selection of Days – This option allows the user to select which set of model days to 

display or which days to include in a displayed average. The Worst or Best 20% 

IMPROVE days options select modeled days identical with the 2002 IMPROVE 

Worst and Best days. The IMPROVE Sampled option uses all modeled days that 

correspond to available IMPROVE days in 2002. The All Days option uses all 365 

modeled days for 2002.

Averaging – This option allows the user to select daily, monthly, and annual 

averaging periods for display.

Quarter – This option allows the user to select one or more specific quarters.

Chart Type – This option allow the user to select between a Timeline, which plots 

each parameter as in independent line graph, and Bar Chart, which plots single 

parameters as a bar and multiple parameters as a stacked bar.

The graphic displays cannot be altered beyond the selections described above. They can 

be saved or copied by right-clicking and making the appropriate selection. The data table below 

the graphic can be copied and pasted into spreadsheet software such as Microsoft Excel.
29

Figure 18. Modeling: Model Performance Tool. This tool allows users to determine model 

performance for individual IMPROVE monitoring sites.

Tool Control Panel

Note the options

selected include:

1. Species mass comparisons

2. Revised IMPROVE algorithm

Click 

for 

Help

Modeled data on the left; 

Monitored data on the right

Note agreement or 

difference between 

species

Tool Control Panel

Note the options

selected include:

1. Species mass comparisons

2. Revised IMPROVE algorithm

Click 

for 

Help

Modeled data on the left; 

Monitored data on the right

Note agreement or 

difference between 

species
30

MODELING: Visibility Modeling Results Tool

The Visibility Modeling Results tool can be found by clicking on the “Modeling” button 

on the Haze Planning page. The purpose of the Model Performance tool is to allow the user to 

view time series of individual model runs or compare aggregates of different model runs. 

Information regarding the WRAP modeling techniques can be found under the Modeling 

Methods section (http://vista.cira.colostate.edu/TSS/Results/Modeling.aspx). Options for the 

tool’s Control Panel selection boxes are shown in Figure 19 and described below:

Parameter – This option allows the user to select one or more mass or visibility 

parameters to display. There is no option to select extinction parameters. (Note that 

the model results do not include sea salt, though this parameter has been retained for 

consistency across tools.)

IMPROVE Algorithm – The user can select the original or revised IMPROVE 

algorithm. The WRAP recommendation is for states to use the revised algorithm; 

therefore this selection is the default. Due to differences in how species are handled

between algorithms, this choice can affect the selection of worst and best days. This 

generally has a small, but often unexpected effect on resulting averages.

Selection of Days – This option allows the user to select which set of model days to 

display or which days to include in a displayed average. The Worst or Best 20% 

IMPROVE days options select modeled days identical with the 2002 IMPROVE 

Worst and Best days. The IMPROVE Sampled option uses all modeled days that 

correspond to available IMPROVE days in 2002. The All Days option uses all 365 

modeled days for 2002.

Averaging – This option allows the user to select daily, monthly, and annual 

averaging periods for display.

Quarter – This option allows the user to select one or more specific quarters.

Emissions Scenario – This option allows the user to select single or pre-defined pairs 

of emissions scenarios.

Chart Type – This option allow the user to select between a Timeline, which plots 

each parameter as in independent line graph, and Bar Chart, which plots single 

parameters as a bar and multiple parameters as a stacked bar.

The options available on this tool are similar to those available on the “Monitoring: Time 

Series tool,” and individually selected model runs can be displayed in similar ways. When 

viewing model results from pairs of Emissions Scenarios it is helpful to restrict the Averaging

option to Monthly or Annual.

The graphic displays cannot be altered beyond the selections described above. They can 

be saved or copied by right-clicking and making the appropriate selection. The data table below 

the graphic can be copied and pasted into spreadsheet software such as Microsoft Excel.
31

Figure 19. Modeling: Visibility Modeling Results Tool. This tool is very similar to the 

“Monitoring: Time Series Tool”, and allows users to view time series plots of model data and 

compare different model runs.

This set of options 

shows the differences 

between baseline and 

2018 model results

Click 

for 

Help Note the options include 

displaying model data 

from single or paired 

emissions scenarios

Tool 

Control 

Panel

This set of options 

shows the differences 

between baseline and 

2018 model results

Click 

for 

Help Note the options include 

displaying model data 

from single or paired 

emissions scenarios

Tool 

Control 

Panel
32

MODELING: Visibility Projections Tool

Visibility projections are calculated by multiplying a species-specific relative response 

factor (RRF) by the baseline period IMPROVE mass, and then converting to extinction and 

deciview. The RRF is defined as the ratio of future-to-current modeled mass. As an example, 

the projected sulfate extinction is calculated by the following generalized formulas:

1. SO4 RRF = [2018 Modeled Sulfate/Baseline Modeled SO4]

2. Projected SO4 Mass = Baseline IMPROVE SO4 x RRF

3. Projected SO4 Extinction = Conversion via IMPROVE Algorithm of Proj. SO4 Mass

WRAP has defined three RRF calculation methods which differ in how the days for the 

calculation are selected:

Specific Days (EPA) – This is the EPA default method. In this method, single 

species’ RRFs are calculated across observed (i.e., IMPROVE) Worst or Best days in 

the base model year.

Quarterly Weighted – In this method, four (4) quarterly species’ RRFs are calculated 

from the 20% worst or best days in each quarter, regardless of how those days 

compare to the overall annual Worst and Best days.

Monthly Weighted – In this method, twelve (12) monthly species’ RRFs are 

calculated from the 20% worst or best days in each month, regardless of how those 

days compare to the overall annual Worst and Best days.

Details of the visibility projection methodology are described in the Applying Monitoring 

Metrics for Regional Haze Planning on the Planning Information Exchange page 

(http://vista.cira.colostate.edu/TSS/Planning/InformationExchange.aspx).

The Visibility Projections Tool displays data very similar to the “Monitoring: Glide 

Slope Tool,” with the addition of projected visibility values for 2018. Options for the Control 

Panel selection boxes are shown in Figure 20 and described below:

Parameter Group – These options select predetermined groups of parameters, as 

described in the “MONITORING: Time Series Tool.”

Parameter – This option allows the user to select one or more extinction, deciview, 

or mass parameters to display. If parameters with different units are selected 

together, a second y-axis will appear on the left side of the graph. Figure 21 presents 

the visibility projections for the 3 dominant species at the same site depicted in Figure 

20.

Selection of Days – This option allows the user to select between the Worst and Best 

days, based on collected IMPROVE data. The Regional Haze Rule does not require 

states to calculate a glide slope for the Best days, so only the baseline, natural 

conditions, and 2018 projected values are displayed when the Best days option is 

selected.

Annual Data – This option allows the user to select individual annual averages to 

display on the chart, either to provide an understanding of the inter-annual variability 

during the baseline period or to track annual progress beyond the baseline period.
33

RRF Calculation Method – This option allows the user to select among WRAP’s 

three methods for calculating relative response factors (RRFs). The Specific Days 

selection is the EPA default.

Base and Projection Emissions Scenario – This option allows the user to select 

among pairs of WRAP’s base and projected scenarios.

The graphic displays cannot be altered beyond the selections described above. They can 

be saved or copied by right-clicking and making the appropriate selection. The data table below 

the graphic can be copied and pasted into spreadsheet software such as Microsoft Excel.

Figure 20. Modeling: Visibility Projections Tool. This tool is nearly identical to the 

“Monitoring: Glide Slope Tool.” In addition to showing deciview of species glide slopes, this 

tool also displays the projected visibility parameter value for 2018.

Tool Control Panel

Similar to Glide Slope tool, 

with the addition of:

1. RRF Calculation Method

2. Projection Emissions 

Scenario

Click 

for 

Help

Compare the visibility 

projection with the 

glide slope

Estimated Natural 

Conditions

Multiple data tables include what is 

displayed on the chart and RRF values

Baseline 

Conditions

Tool Control Panel

Similar to Glide Slope tool, 

with the addition of:

1. RRF Calculation Method

2. Projection Emissions 

Scenario

Click 

for 

Help

Compare the visibility 

projection with the 

glide slope

Estimated Natural 

Conditions

Multiple data tables include what is 

displayed on the chart and RRF values

Baseline 

Conditions
34

Figure 21. Modeling: Visibility Projections Tool. In this view, species extinction glide slopes 

and 2018 projections are shown for the 3 dominant species at this site.

The sulfate extinction projection 

does not change from Baseline 

conditions

Note the selection of 

the 3 dominant species

The nitrate extinction 

projection shows a 

considerable reduction

The organic matter 

extinction projection 

shows modest reduction

Estimated Natural 

Conditions

The sulfate extinction projection 

does not change from Baseline 

conditions

Note the selection of 

the 3 dominant species

The nitrate extinction 

projection shows a 

considerable reduction

The organic matter 

extinction projection 

shows modest reduction

Estimated Natural 

Conditions