UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 4 ATLANTA FEDERAL CENTER 61 FORSYTH STREET ATLANTA, GEORGIA 30303-8960



### Barry R. Stephens, P. E., Director Tennessee Division of Air Pollution Control Department of Environment and Conservation 9th Floor, 

### L & 

### C Annex 401 Church Street Nashville, Tennessee 37243- 153 1

Dear Mr. Stephens:

Thank you for your September 13,2007, letter concerning the application of the new Interagency Monitoring of Protected Visual Environments (IMPROVE) equation. You requested the use of this new methodology to estimate visibility impacts from three Tennessee facilities to implement the Best Available Retrofit Technology requirement of the Regional Haze Rule. Your letter indicates that the three Tennessee facilities requesting the use of this new methodology are: Eastman Chemical, Alcoa, and DuPont 

### - Old Hickory.

The new methodology uses a spreadsheet developed by the Visibility Improvement 

### - State and Tribal Association of the Southeast to post-process the visibility modeling output from the CALPUFF and CALPOST models. The spreadsheet implements the new IMPROVE equation for calculating visibility impacts that was adopted by the IMPROVE Steering Committee in December 2005. The U. S. Environmental Protection Agency (EPA), Region 4 has previously provided comments indicating that new methodology is 

### an alternative modeling approach and should meet the requirements in Section 3.2 of Appendix W, Guideline on 

### Air Quality Models contained in title 40 of the Code of Federal Regulations (40 C.F.R), Part 5 1. 

### We have reviewed your rationale for using the new methodology. This demonstration included a rationale for the need to use the new IMPROVE equation, a discussion of the performance of the equation versus measured values and a submittal of the modified post-processing methodology. Based on the demonstration provided in your letter, we are approving your request.

We appreciate your desire to protect and preserve the environment. If we may be of further assistance, please contact me or Beverly Banister, Director of the Air, Pesticides and Toxics Management Division, at (404) 562-9077.

Sincerely,

Regional Administrator

Internet Address IURL) http iiwww epa gov Recycled/Recyclable Prcnted NI!~ Vegetable 011 Based Inks on Recywd Faper M,nimum ?O0+ P?stcorsdirer)STATE OF TENNESSEE DEPARTMENT OF ENVIRONMENT AND CONSERVATION DIVISION OF AIR POLLUTION CONTROL 9TH FLOOR, L & C ANNEX 401 CHURCH STREET NASHVILLE, TN 37243-1 531



### September 13,2007

Mr. J. 

### I. Palmer, Regional Administrator US Environmental Protection Agency Atlanta Federal Center 

### 6 1 

### Forsyth Street, SW Atlanta, GA 30303-8909

Re: Request for Approval to use New IMPROVE Equation for BART Modeling

Dear Mr. Palmer,

The Tennessee Division of Air Pollution Control has been working with the Visibility Improvement States and Tribal Association of the Southeast (VISTAS) and EPA Region 4 

### staff
to implement the Best Available Retrofit Technology (BART) requirements of the Regional Haze Rule. As part of this process, the need for a methodology to post-process CALPUFFICALPOST modeling data to implement the new IMPROVE equation was identified. VISTAS asked Dr. Ivar Tombach to develop such a methodology. The resulting spreadsheet and supporting information were submitted by the state of North Carolina to EPA and the Federal Land Managers 

### (FLM) for review. Upon review, EPA Region 4 

### staff commented that they consider this post-processing methodology a non-regulatory modeling application requiring compliance with Section 3.2 of Appendix W, Part 51: Guidance on 

### Air Quality Models 

### and that each individual state must request approval for use of this alternative method. The following information is provided and formal approval for use of this alternative method by Tennessee's affected sources for BART exemption and demonstration modeling is requested.

Rationale for use of the new IMPROVE Equation 

### The new IMPROVE equation, which is a much better representation of the effects of particulate matter on light extinction than the old equation, takes into account the latest scientific understanding of several parameters.

1. The new algorithm overcomes biases of the old algorithm on the haziest days and the clearest days as demonstrated by comparing the measured light extinction from nephelometers at Class 

### I areas to light extinction calculated using each of the equations.1

i1 

### Mr. J. I. Palmer September 13, 2007 Page 2



### 2. The new algorithm recogmzes spatial and temporal variation in light extinction as size distribution of the aerosol changes by increasing extinction efficiency as sulfate, nitrate, and organics concentrations increase.

3. The new algorithm reflects research finding that the mass concentration of particulate organic matter in rural areas is greater than represented by the old equation.

4. The new algorithm includes a NO2 term to represent times when light absorption by NO2 is a meaningful contributor to light extinction.

5. The new algorithm incorporates site-specific Rayleigh scattering values to better represent sites close to sea level or with very hot or cold climates.

6. 

### The new algorithm incorporates a term to reflect the contribution of fine sea salt and its hygroscopic growth with increasing relative humidity recognizing research findings showing that fine sea salt can be an important contributor to light extinction in coastal

areas.

With this combination of revisions to the IMPROVE equation, the resulting apportionment of extinction to various components is more accurate on the haziest and clearest days. This is important for development of emission control strategies since the benefits of control of concentrations of each species will be represented more correctly with the new algorithm. Further discussion of these reasons is included in Enclosure 1.

The spreadsheet developed by 

### Dr. Tombach to implement the entire new IMPROVE equation for use with CALPUFF contains a modification of CALPOST that calculates the light extinction from the CALPUFF output. In their review of the spreadsheet and supporting documentation, EPA Region 4 

### staff commented that the VISTAS methodology contained in the spreadsheet developed by Dr. Tombach appropriately implements the features of the new IMPROVE equation, with the exception of the nitrogen dioxide term. EPA Region 4 further stated that with the addition of their recommendation for addressing the NO2 term, the VISTAS methodology to incorporate the new IMPROVE equation is acceptable on a case-by-case basis upon consultation with the EPA Regional Office. Two Tennessee sources, Eastman Chemical and Alcoa, have requested to use the new IMPROVE equation for their BART determinations. One additional
source, DuPont - 

### Old Hickory, found that the new IMPROVE equation makes a difference for their BART exemption modeling, and have also requested its use.

Equation Performance Versus Measured Values 

### A comparison of the old versus new IMPROVE equation and nephelometer data at several Class I areas is included in Enclosure 1. The old IMPROVE equation tends to show a low bias

on high extinction days. The new equation shows a better match on high extinction days with a slightly high bias. The correlation coefficients are often slightly lower for the new equation than the old equation because there is slightly more scatter at the low end of the equation.\' 

### Mr. J. I. Palmer September 13, 2007 Page 3



### Modified Post-Processing Methodology 

### Since the initial EPA review of the methodology, Dr. Tombach has modified the spreadsheet
to address the NO2 contribution. A copy of the modified spreadsheet and instructions are provided as Enclosure 2 for your review.

We look forward to your response to this request for approval of use of the VISTAS methodology incorporating the new IMPROVE equation by Eastman Chemical, Alcoa, and DuPont - 

### Old Hickory for 

### BART purposes. If you have any questions regarding this correspondence, please contact Julie Aslinger at (61 5) 

### 532-0587. Thank you in advance for your assistance.

Sincerely,

Director Tennessee Division of Air Pollution Control

cc: Kay Prince, EPA Region 4 

### Brenda Johnson, EPA Region 4

### Enclosure 1



## Why Use the New 

## IMPROVE Algorithm?

The new IMPROVE algorithm, which has been approved by the IMPROVE Steering Committee, is a much better representation of the effects of particulate matter on light extinction than the old IMPROVE algorithm. Excellent justification of this conclusion is provided in the November 2005 report of the IMPROVE Steering Committee, "Revised IMPROVE Algorithm for Estimating Light Extinction from Particle Speciation ~ata."'

The new algorithm incorporates changes that represent much of what has been learned about the relationship between particulate matter component concentrations and light extinction in the more than a decade since the old algorithm was developed. The main

reasons that justify using the new algorithm instead of the old one are the following:

The new algorithm overcomes the biases of the old algorithm on the haziest days (when the old algorithm underestimates light extinction) and on the clearest days (when the old algorithm overestimates extinction). This improvement can be seen by comparing measured light scattering from nephelometers with light scattering calculated using either the original IMPROVE equation or the new IMPROVE equation. Figures 1- 3 

### at the end of ths summary illustrate the performance of the

new and old equations compared to nephelometer data for Great Smoky Mountains and Shenandoah National Parks and Cape Romain Wildlife Refuge. Additional examples are available on the Air Resource Specialists ftp site2 and in the IMPROVE report referenced above.

The new algorithm recognizes that light extinction efficiencies vary from location
to location and time to time as the size distribution of the aerosol changes, and it reflects this variation by increasing the extinction efficiency as the concentrations of sulfates, nitrates, and organics increase. It also recognizes that the hurnidityrelated growth rates of particles differ depending on their sizes. As a result, the

new algorithm generally does a better job of representing light extinction at individual sites than does the old algorithm, as indicated by the reduced fractional biases in each 

### RPO region (see Tables 

### 3 and 5 compared to Tables 2 and 4 as copied at the end of this summary from the IMPROVE report.)



### 3. The new algorithm recognizes research findings that show that fine sea salt can be an important contributor to light extinction in coastal areas, and thus includes a new term that reflects its contribution and its hygroscopic growth with increasing relative humidity. The old algorithm ignores sea salt, probably because it was originally developed mainly for inland Class I areas in the inter-mountain West (although incorporating sea salt into the calculation was already considered in a University of California at Davis memo in 1995).

### The new algorithm acknowledges that substantial recent research has shown that the mass concentration of particulate organic matter (often denoted by OMC in IMPROVE publications) in rural areas is a greater multiple of the measured OC concentration than the 1.4 value used in the old algorithm. The new algorithm updates the factor to a more-appropriatel.8.

The new algorithm recognizes that there may be times (near urban areas or in some source emission plumes) when light absorption by NO2 gas is a meaningful contributor to light extinction, and thus includes a new term based on the NO2 concentration.

The new a1 orithm recognizes that the assumption of constant Rayleigh scattering 

# ? of 10 Mm' (representative of an elevation of about 5000 feet) may have been adequate when only inter-mountain West sites were considered, but is a distortion for sites close to sea level or with very hot or cold climates. It thus allows for sitespecific values of the Rayleigh scattering.

At any given location, the net result of all these changes is typically small on average because some changes result in increases in extinction and some in decreases, but the apportionment of that extinction to the various components is more accurate with the new algorithm, especially on the haziest and clearest days. Th~s is particularly important for the development of emission management strategies, because the benefits of control of concentrations of each species will be represented more correctly with the new algorithm.

Figure 

### 1. Aerosol Scattering vs Nephelometer Scattering Comparing New and Old TMPROVE Algorithm and Daily f(RH), Great Smoky Mountains National Park, 1995-

~.

- 

### New IMPROVE Old IMPROVE

### Figure 

### 2. Aerosol Scattering vs Nephelometer Scattering Comparing New and Old IMPROVE Algorithm and Daily f(RH), Shenandoah National Park, 1996-2004.



### New IMPROVE Old IMPROVE

Figure 3. Aerosol Scattering vs Nephelometer Scattering Comparing New and Old IMPROVE Algorithm and 

### Daily f(RH), Cape Romain Wildlife Refuge, 2004.



### New IMPROVE Old IMPROVE

### The Tables below were copied from the report "Revised IMPROVE Algorithm for Estimating 

### Light Extinction from Particle Speciation Data".

Table 

### 2. Averaged fractional bias by RPO for the current IMPROVE algorithm with quintiles based on measured light scattering (criterion 

### 1). Bold font highlights ' 

### the bias values that are lower than corresponding values 

### in Table 3.



### Table 

### 3. Averaged fractional bias by RPO for the current new proposed algorithm with quintiles based on measured light scattering (criterion 

### 1). Bold font highlights the bias values that are lower than corresponding values in Table 

### 2. Quintile 2 0.18 0.27 0.21 Quintile 3 0.10 0.19 0.11 RF'O CEN MANE VISTAS



### RF'O CEN



### Table 4. Averaged fractional bias by RPO for the current IMPROVE algorithm with quintiles based on estimated light scattering (criterion 

### 2). Bold font highlights the bias values that are lower than corresponding values in Table 

### 5. Quintile 1 0.67 0.93 0.59

MANE VISTAS Quintile 4 0.02 0.10 0.02

Quintile 1 

# I Quintile 2 0.51 

## 1 0.08 0.74 0.50

RPO CEN MANE



### Table 

### 5. Averaged fractional bias by RPO for the current new proposed algorithm with quintiles based on estimated light scattering (criterion 

### 2). Bold font highlights the bias values that are lower than corresponding values in Table 4. Quintile 5 -0.1 1 0.01 -0.13

Quintile 3 0.02 Average 0.17 0.28 0.16

0.14 0.16

Quintile 1 0.42 0.35 VISTAS 

# I 0.38 Quintile 4 -0.03

0.19 0.37 WRAP

RPO CEN MANE VISTAS 

### WRAP 0.06 0.11

Quintile 2 0.19 0.27

0.58 Quintile 5 -0.08

0.14 0.26

Quintile 1 0.23 0.15 0.25 0.37 Average 0.10 0.01 0.06

Quintile 3 0.18 0.30 0.08 0.25

Quintile 2 0.11 0.14 0.14 0.19 -0.02 -0.01

Quintile 4 0.09 0.33 0.17 0.16

0.01 0.15

Quintile 3 0.08 0.15 0.08 0.19 Quintile 5 -0.01 0.15 0.16 0.32 Average 0.17 0.28

Quintile 4 0.06 0.19 0.13 0.16 Quintile 5 0.02 0.21 0.2 1 0.17 Average 0.10 0.17 0.16 0.21

### Enclosure 2



## lvar Tombach, Ph. 

## D.

8-7- 

# &*+ 753 Grada Ave. Camarilla, CA 9301 0 805 388-2341 805 445-9424 fax itombach@aol.com



### Instructions: A 

### Postprocessor for Recalculating CALPOST Visibility Outputs with the New IMPROVE Algorithm

Version 2 14 October 2006

Introduction

CALPOST can be used to processes outputs from CALPUFF modeling of a source's emissions
to calculate the 24-hr average visibility impairments caused by primary and secondary particulate
matter attributable to emissions from the modeled source. Those increments are presented in two tables, both labeled "Ranked Daily Visibility Change", in the CALPOST output (.LST) file. The table of interest to us has the subtitle "Modeled Extinction by Species" and lists the dates and locations of such incremental impacts in light extinction (beXt) in ranked order, starting with the

one that represents the largest percentage change in light extinction.'

In addition, with a different setup of the control file CALPOST.INP, the CALPOST postprocessor can be used to calculate 24-hr averages of 

### NO, concentrations. As described below, the outputs from that additional CALPOST run can be used to assess the visibility impact of the NO:! gas in the source plume.

Visibility effects due to particulate matter are calculated in CALPOST from CALPUFF-modeled particulate matter component concentrations using effectively the "traditional" IMPROVE algorithm. CALPOST allows for choice of the humidity scattering enhancement function (f(RH))
to be used with the IMPROVE algorithm; for modeling in connection with the US EPA's Regional Haze Regulations (RHR), the appropriate form of f(RH) is the one described and tabulated in the EPA's 2003 guidance for tracking progress under the RHR. Visibility effects due
to NO2 are not considered in the CALPOST visibility calculation.

Recently, the IMPROVE Steering Committee developed a new algorithm for estimating light extinction from particulate matter component concentrations. This algorithm (the "new IMPROVE algorithm) provides a better correspondence between the measured visibility and

1 The other table in the CALPOST visibility output file, with the subtitle "% of Modeled Extinction by Species", provides equivalent results in terms of changes in the haze index, in deciviews. The two tables represent the same results, with identical ranking of events, while just using different (but mathematically related) metrics.that calculated from particulate matter component concentrations. The new algorithm differs in several substantive ways from the traditional one:

The extinction efficiencies of sulfates, nitrates, and organics have been changed and are

now functions of their concentrations. The extinction efficiencies 

### of sulfate and nitrate

are no longer identical, although the new hygroscopic scattering enhancement factors applied to them are the same.

The concentration of particulate organic matter (POM; variously also labeled OCM or OMC, and sometimes just called "organics") is now taken to be 

### 1.8 times that of the measured organic carbon (OC) concentration. (Confusingly, CALPOST labels the organics concentration as OC.)

The contribution of fine sea salt to light extinction has been added, and is accompanied by its own hygroscopic scattering enhancement factor, 

### f,,(RH).

The light scattering by air itself (Rayleigh scattering) now varies with site elevation and mean temperature. It is to be rounded off to the nearest one 

### ~m" when used with the

new algorithm.

The light absorption by 

### NO;? gas has been added.

The new IMPROVE algorithm is represented by the following f~rmula:~



### bar = 

### 2. 2.fs(RH)*[small sulfate] 

### + 4.8$(RH) *[large sulfate] +2.4.fs(RH)*[small nitrate] 

### + 5. 

### I .fL(RH)*[large nitrate] +2.8*[small organics] 

### + 6. 

### I *[large organics] 

### +I O*[elemental carbon] 

### +I* fine soil] +I. 7ySS(RH)*[sea salt] +0. 6*[coarse matter] +Rayleigh scattering (site speczjic) 

### +O. 33*[NO2@pb)]

The concentrations of "large" and "small" sulfate particles are calculated as follows:



### [large sulfate] = 

### {[total sulfate]/20)*[total sulfate] $[total sulfate] < 

### 20 

### ,ug3

[large sulfate] = 

### [total sulfate] if[total sulfafe] 

### 2 20 

### ,ugh3 (Eqs. 2)


### [small sulfate] = 

### [total sulfate] - 

### [large sulfate].

Identical formulas, with changes in component names, are used for nitrate and organics. In effect, these formulas conclude that low concentrations of these components are mainly in the form of "small" particles with their own extinction efficiency and fs(RH), while high 

## * Square brackets denote concentrations.concentrations (approaching 20 pg/m3) are mainly in the form of "large" particles with 

### a different extinction efficiency and ~L(RH). The scaling factor [total sulfate]/20 sets the fraction of total sulfate that is small.

The sea salt concentration is taken to be 1.8-[Cl] or, if chloride ion measurements are not available, the chlorine concentration can be used in its place. Site specific Rayleigh scattering values have been calculated for all IMPROVE sites.3 Nitrogen dioxide concentrations are not measured at IMPROVE sites, but the ambient NO2 concentrations under natural conditions can be expected to be negligibly small. The higher NO2 concentration in a source plume may be great enough to cause a change in visibility, however.

In order to enable CALPOST to calculate CALPUFF-modeled source impacts on visibility using the new IMPROVE algorithm, it would have to be extensively reprogrammed. As an alternative, such a calculation could be done "off line" by adding another layer of post processing after CALPOST. To this end, 

### I have developed a processor, in the form of an Excel workbook, that takes the CALPOST "Ranked Daily Visibility Change: Modeled Extinction by Species" output table, referenced against default annual average natural conditions concentrations, and creates an equivalent table of results based on the new algorithm. It can also incorporate the visibility impact due to light absorption by NOz in the plume.

The following describes the science behind'the processor (which we'll call the CALPOSTIMPROVE Processor) and provides instructions for using it.

Concepts



### In addition to the mechanical changes imposed by all the new terms in the new LMPROVE formula, applying the new algorithm also requires some conceptual changes. The biggest of these is that the extinction efficiencies of sulfates, nitrates, and organics now depend on the concentrations of those species. The practical implication of this is that extinction is no longer linearly additive. To calculate total extinction, you cannot take a background level of extinction and add to it CALPOST7s calculation of extinction caused by the particulate matter coming fiom a source, because when the two aerosols mix in the atmosphere their combined mass concentration results in increases in the extinction efficiencies of both the background and the

source contribution. This means that combining background particulate matter with the particulate matter from a source gives 

### an extinction result that is greater than the sum of the two separate extinctions.

With the nonlinear behavior resulting from applying the new LMF'ROVE algorithm, the extinction impact of the source (i.e., the increase in extinction resulting from introducing source emissions into the atmosphere) is the sum of three parts:

1. The source impact calculated by the new LMPROVE algorithm using the CALPOST outputs for a plume in isolation;

Revised IMPROVE Algorithm for estimating Light Extinction from Particle Speciation Data. Report to LMPROVE Steering Committee, November 2005.2. 

### An increase in that source impact because the extinction efficiency increases when the source's aerosol combines with the background aerosol; and correspondingly,

3. 

### An increase in the extinction of the background aerosol because of that same mixing.

The total new extinction is the sum of the above three components plus the original background extinction. The original background extinction is just that calculated by the new IMPROVE algorithm from background concentrations of the various components, without any consideration of the effects of the plume. For this application, the background is taken to be that described by EPA's default natural conditions. The difference between the total extinction and the background is the impact of the source.

More details about the calculation are given in the appendix.

Description of Processor

The CALPOST-IMPROVE Processor is a Microsoft Excel workbook that consists of four worksheets. In Version 2 the worksheets are the following.

1. Input & Output - The output table from CALPOST is imported to here and user entries are made for the Rayleigh scattering coefficient and, if desired, for a sea salt concentration at the Class 

### I area of interest. The NO, concentration on each day attributable to the emissions from the source can also be entered together with an assumption of what fraction of the NO, is 

### in the form of NOz. A revised table, with extinction based on the new IMPROVE algorithm is then presented on the same page. This is the only page on which user input takes place, and the results of the calculations appear on this page.

2. Calculations -- The calculations themselves are all done on this worksheet. There is no

user input to this page. The variables are explained on the worksheet itself, so the user can find intermediate values if so inclined.



### 3. F(RH) - This worksheet tabulates the traditional IMPROVE f(RH) against 

### RH, and then also lists values for the three new humidity growth functions, fs(RH), ~L(RH), and fss(RH). It serves as a lookup table for the "Calculations" worksheet.

4. Rayleigh & Sea Salt - This page tabulates the IMPROVE-recommended Rayleigh scattering coefficients for all VISTAS Class I areas and for Class 

### I areas in adjacent
states. It also lists the average sea salt concentrations for the same locations, as tabulated on the VIEWS web site, based on chloride or chlorine measurements by LMPROVE monitors between 2000 and 2004. This sheet just provides information for the user; it is
not linked to the rest of the workbook. The user can obtain Rayleigh and sea salt numbers for the Class I area of interest from this table and then manually enter them in the designated spaces in worksheet 1.

### lnstructions for Using the 

### CALPOST-IMPROVE Processor

These instructions apply to Version 

### 2 of the processor. Version 

### 2 includes the ability to calculate the light extinction effects of NOz resulting fiom the source's emissions.

Step 1. Begin by opening the output (.LST) file from a CALPOST visibility calculation run in a text editor or word processing program.4 In the second half of the file, locate the table "Ranked Daily Visibility Change" with the subheading "Modeled Extinction by ~~ecies".~

Step 

### 2. Copy this table and paste it onto a new page. Save it as a text (.txt) file, not as a formatted (e.g., MS Word .doc or .rtf) file. The final table should contain only the column headings and the data. Delete all other captions, any additional data summaries at the end, and blank lines before or after the table. The processor can handle a maximum of 

### 22 lines of data (i.e., the highest rank in the last, unlabeled, column should be 22) plus a row of column captions. Delete 

### any data that exceed this limit. (Fewer than 

### 22 lines of data are OK.) The result should look like the example in Figure 1, although the line wrapping may differ.

Step 3. Open the CALPOST-IMPROVE Processor in Microsoft Excel. Save the open file under a

new name so that the original empty processor will remain available for future use. The front worksheet, labeled "Input & Output" looks like Figure 

### 2. There is a large empty box, surrounded by double lines, into which the table created above will be imported, as described be10w.~ On the right is a box into which NO, concentrations may be entered manually, and a small box below this box is provided for entry of the user's assumption of what fraction of that NO, is in the form of N02. Two smaller boxes provide for user input of the Rayleigh scattering coefficient and, optionally, sea salt concentration for the Class 

### I area, as described below. Results of the new IMPROVE algorithm calculations appear in blue in the lower half of the worksheet and some additional results, that are also useful for quality control, appear 

### in green to the right of the large box. At the moment, many results cells will display nonsensical numbers and error messages, such as shown in Figure 

### 2.

Step 4. Select the upper left cell (A7) in the large box. On the Excel menu bar, go to 

### Data>Get External Data and click on 

### lmport Text ~ile.' (If the large box is not empty, click on 

### Edit Text Import instead.) Select the file that contains the table created in Step 2 and click on the 

### Get Data button. Go through the Text Import Wizard steps, checking that all values appear correctly in separate columns. (The label "COORDINATES 

### (krn)" will be split over two columns; this is OK.) When everything appears in order, click 

### Finish.

4 The background concentrations that were entered into CALPOST must be the EPA-prescribed default annual average natural conditions concentrations for the East. The processor will not give correct answers if other concentrations were used in CALPOST.

For hture reference in Step 7, this may also be a good time to locate the table with the same title but with the subtitle "% of Modeled Extinction by Species", which appears later in the output file.

If the workbook has already been used, the boxes may not be empty. This does not matter. The exact wording may vary slightly between different versions of Microsoft Excel. The terminology used here is from Excel 2004 for Macintosh.YEAR DAY HR RECEPTOR COORDINATES (km) TYPE BEXT(Mode1) BEXT(BKG) BEXT(Tota1) %CHANGE F(RH) bxSO4 bxN03 bxOC bxEC bxPMC bxPMF



### Figure 1. 

### Example of CALPOST Output Table, in Proper Format for Importing into the CALPOST-IMPROVE Processor.

Step 5.' The "Import Data" window will appear, with cell A7 indicated as the location at which data will be entered. Click on the Properties button. 

### In the window that appears, select "Overwrite existing cells with new data, clear unused cells" and uncheck "Adjust column width", then click on 

### OK. Now click on the 

### OK button in the "Import Data" window.

Step 

### 6. Assuming that your Excel application is set up to automatically recalculate whenever any entries are changed, you should now have filled the cells in the large box on the first worksheet,

8 If the processor already had data in it and 

### Edit Text Import was clicked in Step 4, then the "Import Data" window will not appear and Step 5 can be skipped.numbers should have appeared in the green columns to the right, and some numbers will have appeared in the output table in blue on the lower half of the worksheet. If the data import worked properly, none of the imported data should have spilled out of the large box. Check that all the column captions in bold outside the large box are now duplicated on the first line in the box. (There won't be a caption for Rank.)

Step 7. As a further check on whether everything is correct so far, the dv information in the three columns to the right of the large box should be the same as that in the second CALPOST table "Ranked Daily Visibility Change: % of Modeled Extinction by Species", which was mentioned in Footnote 1.

Step 8. Beneath the large box that was just filled with imported data, enter the Rayleigh scattering coefficient for the Class I area of interest into the top small box after red instruction 3. Also, if you wish, fill in the other small box, the one after red instruction 4, with the annual average sea salt concentration. (The sea salt box may be left blank, but the Rayleigh scattering coefficient box must be filled in.) To help with filling in these two boxes, the fourth worksheet, "Rayleigh & Sea Salt", provides IMPROVE-calculated values of the Rayleigh coefficients for Class I areas in the VISTAS region and in adjacent states. Also, average sea salt concentrations for 2000-2004, calculated in accordance with the new IMPROVE procedures, can be found there.

Step 

### 9.9 If the impact due to NO2 is to be considered, a second CALPOST 

### run will be needed to provide the 24-hr average NO, concentrations estimated by CALPUFF. For this purpose, run CALPOST using the ASPEC = NOX option in Input Group 1 of the CALPOST.INP control file. The NO, values to insert in the NO, input box on the Lnput & Output page of the processor have to be extracted manually from the CALPOST output file for each date and receptor listed in the file that was imported in Steps 1 through 5 above and are displayed in the left hand columns in the large box.

Step 10. Select a value between 0 and 1 to represent what fraction of NOx is in the form of NO2. Enter this value into the small box at red instruction 6 below the column where the NO, concentrations were entered.''

Step 11. The blue data table at the bottom of the page represents the new IMPROVE algorithm outputs. An example is shown in Figure 3. This table can be compared with the original CALPOST table at the top of the page. All of the columns in both tables show exactly the same variables, except that the 

### F(RH) column in the top table is replaced by just the 

### RH in the lower table (since the new procedure has three different f(RH) functions) and a new baN02 column has been added to the bottom table to show the light absorption due to NO2 (in 

### ~m"). Although the events are listed in the same order in both tables, note that their rankings may have changed, as is the case for many of the lines in the blue output table in Figure 

### 3.

9 Steps 8 and 9 are optional. If the impact due to NO2 is not of interest, just leave the entry fields mentioned in these steps blank.
10 An easy way to see the effect of the NO2 on the source's impact in the output table in the lower half of the page is to toggle this N02/N0, value between the selected value and zero.For those who are interested in more detail concerning the calculations that take place, values of the three f(RH) functions appear in columns 

### M through 

### 0 on the second, "Calculations" spreadsheet. The extinction impact of the source, including enhancement of the extinction efficiencies for sulfates, nitrates, and organics because of greater total

mass concentrations, appears 

### in columns 

### V through AC. Extinction due to the annual
average natural background appears in Columns AJ through AN; natural background extinctions for those components that are enhanced by greater total mass concentrations
appear in columns AU through 

### AX.

### Appendix Details of Calculation Approach

As an example of the calculation steps, assume that the sulfate concentration resulting Gom emissions from a source is [SE] and the sulfate 

### in the undisturbed natural background is [SN], for a total ambient sulfate concentration of [ST]. According to Equations 1 and 2 

### in the main body of this document, the total extinction due to sulfate for this combination is



### bat(sulfate) = 

### 2.2.fs(RH)*[small myate]+ 4.8.fL(RH)*[large sulfate], (Eq. A-1)

where



### [small sulfate^] = 

### [ST] - 

### [large sulfate^],

and the subscript T denotes total sulfate

For the original background, where there is no source impact, the corresponding formulas for the terms in Equations A-2 are



### [small sulfated = 

### [SN] - 

### [large sulfatenil,

where the subscript N denotes natural sulfate.

Similar calculations need to be carried out for nitrates. Contributions of the other particulate components are linear and can just be calculated according to Equation 1.

If the impact due to NO2 is also to be considered, then the source impact due to this component is, according to Equation 1,

where [NO*] is in ppb. It is reasonable to assume that the ambient NOz concentrations under natural conditions would be so small as to cause negligible light absorption, so the corresponding term is not needed in the natural conditions calculation.

The contributions due to the various components are summed together as in Equation 1 to obtain the total extinction bext,~ and the natural background extinction bext,~ The

### fractional change in extinction is then calculated as the difference, normalized by the natural background extinction

a result that can also be expressed in deciviews.

These formulas are used in the CALPOST-IMPROVE Processor. Similar formulas apply for nitrates and organics. There is no nonlinearity 

### in the remaining terms in Equation 1.CALPOST-IMPROVEProcessorfortheEastREVISEDDRAFT2August2006'-CALPOSTRecalculationwith NewIMPROVE Algorithm............................INPUTfromCALPOST(basedonoldIMPROVEalgorithm)Verston2.29Sept.20061.AtcellA7,import"RankedDallyVisibility Change"(bext)table,lncludlngcolumn5.Checkcalculatedvalues3.(Optlonal)headings,fromCALPOST(22days,max)below agalnstCALPOST'sEnter24hr"Ranked DallyVlslbllltyNOXwnc.YEAR DAYHRRECEPTORCOORDINATES(km)TYPEBEXT(Mode1)BEXT(BKGBEXT(Tota1)%CHANGEF(RH)bxS04bxN03bxOCbxECbxPHCbxPMFRankNOx(ppb)Iriiola1)dv(bhq)Aov""PI'NU"'""I1-11$NUMIiNUWIINUNUM1IVNIJM':!NU!>?'3.Enter value of slte-speclflcRayleighscatteringcoeffldent,from "Raylelgh&!SeaSalt"E6.Enter desiredN02/NOxratioworksheet(defaultIs0)4.(Optlonal)Insertannual averageseesaltconcentration, from "Raylelgh&SeaSalt"worksheet. Leave blankifnotused,1.e.defaultIs0...................................OUTPUT(basedonnewIMPROVE algorithm),. . . . . . .... ..NewYEARDAYHRRECEPTORCOORDINATES(km)TYPEBEXT(SourceBEXT(BKGBEXT(Tota1)OhCHANGEiR~tl%jjbsS04bsNO3bsOCbSECbsPMCbSPMFbaN02Rankdv(t0tal)dv(bk9)Adv0000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#NIA0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/AfN/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000000#N/A#N/A#N/A#N/A#N/A#N/A#NIA000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/ABNIA000001#N/A#N/A0.000000 000#N/A#N/A#N/A#N/A#N/A#N/A#N/A000001#N/A#N/A0.00

# -
--NNNNNNNNNNNNNNNNNNNNNN muaQaaaQaaaQaaWQaaaQaaaW c0111?????111???????111- OCOOOOOOOOOOOOOOOOOOOOOO 'ii 0 !!?a

### Old 

### and New F(RH) 

### Values Old F(RH) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1.02 1.04 1.06 1.08

1.1 1.13 1.15 1.18

1.2 1.23 1.26 1.28 1.31 1.34 1.37 New Fs(RH) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1.38

1.4 1.42 1.44 1.46 1.48 1.49 1.51 1.53 1.55 1.57 1.59 1.62 1.64 1.66 New FI(RH) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1.31 1.32 1.34 1.35 1.36 1.38 1.39 1.41 1.42 1.44 1.45 1.47 1.49

1.5 1.52 New Fss(RH) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2.36 2.38 2.42 2.45 2.48

### Salt concentratibnsfor Class I Areas of VISTAS and Nearby States 

# *

Class I Area

VISTAS States Cape Romain W Chassahowitzka W Cohutta W Dolly Sods W Everglades NP Great Smoky Mtns. NP lames River Face W. Linville Gorge Mammoth Cave NP Okefenokee W Otter Creek W St. Marks W. Shenandoah NP Shining Rock W Si psey W Swanquarter W Wolf Island W. Wolf Island W.**

Nearby States Breton W Brigantine W Caney Creek Hercules-Glades Mingo W Upper Buffalo W State bRay Mm-1 Sea Salt IMPROVE W/m3 Monitor

0.20 0.08 0.03 0.02 0.31 0.02 0.02 0.02 0.02 0.09 0.02 DOSOl 0.03 0.02 0.03 0.05 0.13 0.09 OKEFl 0.20 ROMAl

Unknown 0.22 0.03 0.04 0.01 0.03 

## * Rayleigh scattering values for the relevant IMPROVE monitor are from the IMPROVE memo about the revised algorithm. Sea salt concentrations are averages for 2000-2004 based on data from the VIEWS web site. 

## ** Alternative values for Wolf Island based on Cape Romain measurements. Being at sea level and on the coast, Cape Romain values may be more representative of Rayleigh and sea salt conditions at Wolf island than those at Okefenokee, which is above sea level and far from the shore.