Interagency Monitoring of Protected Visual Environments

IMPROVE

CIRA

Cooperative Institute for

Research in the Atmosphere

CIRA

Cooperative Institute for

Research in the Atmosphere

IMPROVE

Spatial and Seasonal Patterns

and Temporal Variability of Haze

and its Constituents in the

United States

Spatial and Seasonal Patterns

and Temporal Variability of Haze

and its Constituents in the

United States

ISSN ISSN 0737-5352-87 0737-5352-87

Report V eport V

June 2011 June 2011

Acadia NP

1990 1995 2000 2005 2010

Year

0

2

4

6

8

(μg/m )3

50th Percentile

PM2.5
In celebration of the IMPROVE network’s 25th anniversary, we dedicate this report to all 

of the hard working operators, technicians, and scientists who have contributed to the 

success of the IMPROVE network over the years.

Description of the cover:

The front cover displays a split screen of two images from Acadia National Park that 

represent visibility levels corresponding to the 50th percentile, PM2.5 fine mass aerosol 

concentrations in 1989 (left) compared to those in 2008 (right). A noticeable 

improvement in visibility levels occurred due to the decrease in aerosol concentrations 

over the 20-year span. We used the WinHaze 2.9.9 computer software program (Air 

Resource Specialists, 2011), a powerful tool for visualizing the impact of aerosol trends 

on visibility conditions.
IMPROVE REPORT V

Spatial and Seasonal Patterns and Temporal Variability of Haze

and its Constituents in the United States

Report V

ISSN 0737-5352-87

Principal Author:

Jenny L. Hand1

1Cooperative Institute for Research in the Atmosphere

Colorado State University

Fort Collins, CO 80523-1375

Contributors:

Scott A. Copeland1

Derek E. Day1

Ann M. Dillner2

Hege Indresand2

William C. Malm1

Chuck E. McDade2

Charles T. (Tom) Moore, Jr.3

Marc L. Pitchford4

Bret A. Schichtel5

John G. Watson6

2Crocker Nuclear Laboratory

University of California 

Davis, CA 95616-8569

3Western Governors’ Association – Western Regional Air Partnership

CSU/CIRA

Fort Collins, CO 80523-1375

4National Oceanic and Atmospheric Administration

Desert Research Institute

Las Vegas, NV 89119-7363

5National Park Service

CSU/CIRA

Fort Collins, CO 80523-1375

6Desert Research Institute

Reno, NV 89512

Disclaimer

The assumptions, findings, conclusions, judgments, and views presented herein are those of the 

authors and should not be interpreted as necessarily representing the National Park Service or 

National Oceanic and Atmospheric Administration policies.
i

IMPROVE REPORT V

TABLE OF CONTENTS

Overview and Summary ..............................................................................................................S-1

S.1 Introduction............................................................................................................S-1

S.2 Aerosol Data ..........................................................................................................S-2

S.3 Spatial Patterns in Rural and Urban Speciated Aerosol Concentrations: 

Implications for Urban Excess....................................................................................S-7

S.3.1 Ammonium Sulfate.........................................................................................S-8

S.3.2 Ammonium Nitrate.........................................................................................S-9

S.3.3 Particulate Organic Matter............................................................................S-10

S.3.4 Light Absorbing Carbon...............................................................................S-11

S.4 Seasonal Distributions in Aerosol Mass Concentrations.....................................S-12

S.4.1 Ammonium Sulfate.......................................................................................S-13

S.4.2 Ammonium Nitrate.......................................................................................S-13

S.4.3 Particulate Organic Matter............................................................................S-14

S.4.4 Light Absorbing Carbon...............................................................................S-15

S.4.5 PM2.5 Soil Mass.............................................................................................S-15

S.4.6 PM2.5 Gravimetric Fine Mass........................................................................S-16

S.4.7 Discussion.....................................................................................................S-17

S.5 Spatial and Seasonal Patterns in Relative Reconstructed Aerosol Light Extinction 

Coefficients ...............................................................................................................S-18

S.5.1 Deciview.......................................................................................................S-19

S.5.2 Ammonium Sulfate Light Extinction Coefficients.......................................S-21

S.5.3 Ammonium Nitrate Light Extinction Coefficients.......................................S-24

S.5.4 Particulate Organic Matter Light Extinction Coefficients............................S-24

S.5.5 Light Absorbing Carbon Light Extinction Coefficients...............................S-24

S.5.6 PM2.5 Soil Mass Light Extinction Coefficients ............................................S-25

S.6 Trends in IMPROVE Speciated Aerosol Mass Concentrations..........................S-25

S.6.1 Sulfate Ion Trends.........................................................................................S-26

S.6.2 Nitrate Ion Trends.........................................................................................S-27

S.6.3 Total Carbon Trends.....................................................................................S-29

S.6.4 Gravimetric PM2.5 Fine Mass Trends............................................................S-30

S.7 Regional Haze Rule Metrics ...............................................................................S-32

References..................................................................................................................S-33
ii

IMPROVE REPORT V

Chapter 1. Interagency Monitoring of Protected Visual Environments (IMPROVE) Network: 

Configuration and Measurements................................................................................................ 1-1

1.1 Introduction............................................................................................................ 1-1

1.2 Overview of the Improve Monitoring Network..................................................... 1-3

1.2.1 Site Location ................................................................................................... 1-3

1.2.2 Aerosol Sampling and Analysis.................................................................... 1-14

1.2.3 Optical Sampling and Analysis..................................................................... 1-19

1.3 Protocol and Equipment Changes........................................................................ 1-25

1.3.1 Analytical Changes....................................................................................... 1-25

1.3.1.1 Introduction of a New Model Carbon Analyzer .................................... 1-25

1.3.1.2 Transition from He Flush to Vacuum Chamber Cu-Anode XRF.......... 1-26

1.3.1.3 Introduction of New Calibration Foils for Mo-Anode XRF.................. 1-26

1.3.1.4 Processing XRF Calibration Data.......................................................... 1-27

1.3.1.5 New XRF Quality Assurance Reports & Clarification of Data Acceptance 

Criteria ............................................................................................................... 1-28

1.3.2 Sampling Equipment Changes...................................................................... 1-28

1.3.2.1 Filter Masks Removed ........................................................................... 1-28

1.3.2.2 Quartz Backup Filters Added at Six Sites.............................................. 1-29

1.3.2.3 New Cassette Design for the IMPROVE Sampler ................................ 1-29

1.3.3 Data Processing Changes.............................................................................. 1-33

1.3.3.1 Change in the Definition of Flow Rate Native Flags............................. 1-33

1.3.4 Changes or Interferences Noted Through Data Analysis ............................. 1-34

1.3.4.1 Sulfur Interference in the Determination of Silicon .............................. 1-34

1.3.4.2 Shifts in the S/SO4

= Ratio ..................................................................... 1-34

1.4. Chemical Speciation Network ............................................................................ 1-35

References.................................................................................................................. 1-45

Chapter 2. Spatial Patterns of Speciated PM2.5 Aerosol Mass Concentrations....................... 2-1

2.1 Aerosol Species Composition................................................................................ 2-3

2.1.1 PM2.5 Ammonium Sulfate Mass Concentrations............................................ 2-4

2.1.2 PM2.5 Ammonium Nitrate Mass Concentrations ............................................ 2-4

2.1.3 PM2.5 Particulate Organic Matter and Light Absorbing Carbon Mass 

Concentrations ..................................................................................................................... 2-4

2.1.4 PM2.5 Soil Mass Concentration....................................................................... 2-7
iii

IMPROVE REPORT V

2.1.5 PM2.5 Sea Salt Mass Concentration ................................................................ 2-8

2.1.6 PM2.5 Gravimetric Fine Mass and Reconstructed Fine Mass ......................... 2-8

2.1.7 PM2.5 Mass Difference.................................................................................... 2-8

2.1.8 PM10 and Coarse Mass Concentrations........................................................... 2-9

2.2 Spatial Patterns in Annual Mean Mass Concentrations......................................... 2-9

2.2.1 PM2.5 Ammonium Sulfate Mass ..................................................................... 2-9

2.2.2 PM2.5 Ammonium Nitrate Mass.................................................................... 2-12

2.2.3 PM2.5 Particulate Organic Matter Mass ........................................................ 2-15

2.2.4 PM2.5 Light Absorbing Carbon Mass............................................................ 2-18

2.2.5 PM2.5 Soil Mass............................................................................................. 2-21

2.2.6 PM2.5 Sea Salt Mass...................................................................................... 2-24

2.2.7 PM2.5 Gravimetric Fine Mass........................................................................ 2-26

2.2.8 PM2.5 Reconstructed Fine Mass.................................................................... 2-28

2.2.9 Differences in PM2.5 Gravimetric and Reconstructed Fine Mass................. 2-29

2.2.10 Coarse Mass................................................................................................ 2-31

2.2.10 PM10 Mass................................................................................................... 2-32

References.................................................................................................................. 2-33

Chapter 3. Reconstructed Aerosol Light Extinction Coefficients ............................................... 3-1

3.1 IMPROVE Aerosol Light Extinction Coefficient Algorithm................................ 3-1

3.2 PM2.5 Ammonium Sulfate Light Extinction Coefficients...................................... 3-5

3.3 PM2.5 Ammonium Nitrate Light Extinction Coefficients...................................... 3-7

3.4 PM2.5 Particulate Organic Matter Light Extinction Coefficients......................... 3-10

3.5 PM2.5 Light Absorbing Carbon Light Extinction Coefficients............................ 3-13

3.6 PM2.5 Fine Soil Light Extinction Coefficients..................................................... 3-16

3.7 PM2.5 Sea salt Extinction Coefficients................................................................. 3-18

3.8 PM2.5 Reconstructed Aerosol Light Extinction Coefficients............................... 3-21

3.9 Coarse Mass Light Extinction Coefficients......................................................... 3-22

3.10 PM2.5 Deciview.................................................................................................. 3-24

References.................................................................................................................. 3-25

Chapter 4. Seasonal Distributions of PM2.5 Aerosol Mass Concentrations................................. 4-1

4.1 PM2.5 Ammonium Sulfate Mass Concentrations................................................... 4-2

4.2 PM2.5 Ammonium Nitrate Mass Concentrations ................................................. 4-22

4.3 PM2.5 Particulate Organic Matter Mass Concentrations...................................... 4-26
iv

IMPROVE REPORT V

4.4 PM2.5 Light Absorbing Carbon Mass Concentrations ......................................... 4-30

4.5 PM2.5 Soil Mass Concentrations .......................................................................... 4-34

4.6 PM2.5 Sea Salt Mass Concentrations.................................................................... 4-38

4.7 PM2.5 Gravimetric Fine Mass Concentrations ..................................................... 4-42

4.8 Coarse Mass Concentrations................................................................................ 4-44

4.9 Discussion............................................................................................................ 4-49

References.................................................................................................................. 4-51

Chapter 5. Seasonal Distribution of PM2.5 Reconstructed Aerosol Light Extinction 

Coefficients.................................................................................................................................. 5-1

5.1 PM2.5 Ammonium Sulfate Light Extinction Coefficients...................................... 5-1

5.2 PM2.5 Ammonium Nitrate Light Extinction Coefficients.................................... 5-21

5.3 PM2.5 Particulate Organic Matter Light Extinction Coefficients......................... 5-27

5.4 PM2.5 Light Absorbing Carbon Light Extinction Coefficient.............................. 5-32

5.5 PM2.5 Soil Light Extinction Coefficients............................................................. 5-36

5.6 PM2.5 Sea Salt Light Extinction Coefficients....................................................... 5-42

5.7 PM2.5 Reconstructed Aerosol Light Extinction Coefficients............................... 5-46

5.8 Coarse Mass Light Extinction Coefficients......................................................... 5-48

5.9 PM2.5 Deciview.................................................................................................... 5-52

5.10 Summary............................................................................................................ 5-53

References.................................................................................................................. 5-53

Chapter 6. Trends in IMPROVE Speciated Aerosol Concentrations...................................... 6-1

6.1 Sulfate Ion Trends.................................................................................................. 6-3

6.2 Nitrate Ion Trends................................................................................................ 6-14

6.3 Total Carbon Trends............................................................................................ 6-18

6.4 PM2.5 Soil Trends................................................................................................. 6-26

6.5 Gravimetric PM2.5 Fine Mass Trends .................................................................. 6-36

6.6 Coarse Mass Trends............................................................................................. 6-44

6.7 PM10 Gravimetric Mass Trends........................................................................... 6-53

References.................................................................................................................. 6-60

Chapter 7. Urban Excess in PM2.5 Speciated Aerosol Concentrations........................................ 7-1

7.1 Introduction and Method........................................................................................ 7-1

7.2. Ammonium Sulfate............................................................................................... 7-4

7.3 Ammonium Nitrate ................................................................................................ 7-7
v

IMPROVE REPORT V

7.4 Particulate Organic Matter................................................................................... 7-10

7.5 Light Absorbing Carbon ...................................................................................... 7-14

7.6 PM2.5 Gravimetric Fine Mass............................................................................... 7-17

7.7 Summary.............................................................................................................. 7-20

References.................................................................................................................. 7-22

Chapter 8. Uncertainties in PM2.5 Gravimetric and Speciation Measurements........................... 8-1

Abstract........................................................................................................................ 8-1

Implications.................................................................................................................. 8-1

8.1 Introduction............................................................................................................ 8-2

8.2 Sample Collection Systems.................................................................................... 8-3

8.2.1 Interagency Monitoring of Protected Visual Environments (IMPROVE) ..... 8-4

8.2.2 The Chemical Speciation Network (CSN)...................................................... 8-5

8.2.3 Exploration of the Differences in the IMPROVE and CSN Carbon 

Measurements...................................................................................................................... 8-5

8.2.4 Relating CSN to IMPROVE Carbon Concentrations..................................... 8-9

8.2.4.1 Converting CSN to IMPROVE Carbon Concentrations........................ 8-10

8.2.5 Comparison of Reconstructed to Measured Mass ........................................ 8-13

8.3 Investigating Bias Associated with each Species ................................................ 8-20

8.3.1 Bias in Gravimetric Mass.............................................................................. 8-28

8.3.2 Bias in Reconstructed Mass.......................................................................... 8-29

8.4 Spatial and Seasonal Variability in PM2.5 and RPM2.5 Biases............................. 8-29

8.5 Summary.............................................................................................................. 8-33

References.................................................................................................................. 8-35

Chapter 9. Regional Haze Rule Progress Tracking Metrics.................................................... 9-1

9.1 Introduction............................................................................................................ 9-1

9.2 Regional Haze Rule Assessment ........................................................................... 9-2

9.2.1 Uniform Rate of Progress ............................................................................... 9-2

9.2.2 Regional Haze Rule Metric............................................................................. 9-4

9.3 Assessment of Change in Regional Haze from the Baseline (2000–2004) to 

Period 1 (2005–2009).................................................................................................. 9-6

9.4 Case Studies of Regional Haze Rule Progress..................................................... 9-14

9.4.1 Boundary Waters Canoe Area Wilderness, Minnesota................................. 9-14

9.4.2 Great Smoky Mountains National Park, Tennessee/North Carolina ............ 9-17
vi

IMPROVE REPORT V

9.4.3 Mesa Verde National Park, Colorado ........................................................... 9-20

9.4.4 Hell’s Canyon Wilderness, Oregon/Idaho .................................................... 9-25

9.4.5 Agua Tibia Wilderness, California ............................................................... 9-30

References.................................................................................................................. 9-35

Chapter 10. X-Ray Fluorescence Reference Materials from an Aerosol Generation System..........

................................................................................................................................................... 10-1

10.1 Introduction........................................................................................................ 10-1

10.2 Aerosol Generation System ............................................................................... 10-1

10.3 Testing and Verification .................................................................................... 10-3

Chapter 11. Ammonia and Ammonium Measurements from Passive, Modified IMPROVE and 

CASTNET Samplers.................................................................................................................. 11-1

11.1 Introduction........................................................................................................ 11-1

11.2 Instrumentation .................................................................................................. 11-2

11.2.1 URG Sampler.............................................................................................. 11-3

11.2.2 IMPROVE Sampler .................................................................................... 11-3

11.2.3 CASTNET Sampler .................................................................................... 11-4

11.2.4 Passive Samplers......................................................................................... 11-5

11.3 Comparisons of Data from CASTNET, URG, and IMPROVE Samplers......... 11-6

11.3.1 IMPROVE versus URG.............................................................................. 11-6

11.3.2 CASTNET versus URG............................................................................ 11-12

11.3.3 Ammonia Comparisons from CASTNET, Passive, and URG Samplers.. 11-20

11.4 Summary.......................................................................................................... 11-20

References................................................................................................................ 11-21

Chapter 12. IMPROVE Measurements Bibliography ............................................................... 12-1

Appendices available at 

http://vista.cira.colostate.edu/improve/Publications/improve_reports.htm or on cd by request.

Appendix A: Comparisons of IMPROVE and CSN 2005–2008 Daily Speciated Aerosol 

Concentrations at Collocated Sites

Appendix B: 2005–2008 Annual Mean Mass Concentrations and PM2.5 Mass Fractions for Each 

Site

Appendix C: 2005–2008 Annual Mean Reconstructed Light Extinction Coefficients (bext) and 

PM2.5 bext Fractions for Each Site

Appendix D: 2005–2008 Regional Monthly Mean Mass Concentrations and PM2.5 Mass 

Fractions
vii

IMPROVE REPORT V

Appendix E: 2005–2008 Regional Monthly Mean Mass Concentrations and PM2.5 Mass 

Fractions

Appendix F1: IMPROVE 20-Yr Normalized Trends (1989–2008)

Appendix F2: IMPROVE 9-Yr Normalized Trends (2000–2008)

Appendix G: Supplemental Analysis for Chapter 9

G.1. Regional Haze Rule IMPROVE Progress Tracking Site Data Results by State

G.2. Spatial Maps of Regional Haze Rule Metrics
viii

IMPROVE REPORT V

LIST OF FIGURES

Figure S.2.1. Locations of IMPROVE and IMPROVE protocol sites for all discontinued and 

current sites. The IMPROVE regions used for grouping the sites are indicated by shading and 

bold text. Urban sites included in the IMPROVE network for quality assurance purposes are 

identified by stars.........................................................................................................................S-4

Figure S.2.2. Current and discontinued Chemical Speciation Network (CSN) sites (grey and 

orange) operated by the Environmental Protection Agency. Regions are shown as shaded areas 

and bold text. The sites included in the analyses in this report are shown as orange circles.......S-5

Figure S.3.1. (a) IMPROVE and CSN PM2.5 ammonium sulfate (AS) 2005–2008 annual mean 

mass concentrations (μg m-3). (b) Interpolated ratios of urban (CSN) to rural (IMPROVE) annual 

mean AS concentrations for 2005–2008. IMPROVE sites are shown as circles; CSN sites used in 

the analysis are shown as squares. CSN sites with no IMPROVE site within 150 km are shown as 

triangles. These sites were not used in the analysis.....................................................................S-9

Figure S.3.2. (a) IMPROVE and CSN PM2.5 ammonium nitrate (AN) 2005–2008 annual mean 

mass concentrations (μg m-3). (b) Interpolated ratios of urban (CSN) to rural (IMPROVE) annual 

mean AN concentrations for 2005–2008. IMPROVE sites are shown as circles; CSN sites used 

in the analysis are shown as squares. CSN sites with no IMPROVE site within 150 km are shown 

as triangles. These sites were not used in the analysis...............................................................S-10

Figure S.3.3. (a) IMPROVE and CSN PM2.5 particulate organic matter (POM) 2005–2008 

annual mean mass concentrations (μg m-3). (b) Interpolated ratios of urban (CSN) to rural 

(IMPROVE) annual mean POM concentrations for 2005–2008. IMPROVE sites are shown as 

circles; CSN sites used in the analysis are shown as squares. CSN sites with no IMPROVE site 

within 150 km are shown as triangles. These sites were not used in the analysis. ....................S-10

Figure S.3.4. (a) IMPROVE and CSN PM2.5 light absorbing carbon (LAC) 2005–2008 annual 

mean mass concentrations (μg m-3). (b) Interpolated ratios of urban (CSN) to rural (IMPROVE) 

annual mean LAC concentrations for 2005–2008. IMPROVE sites are shown as circles; CSN 

sites used in the analysis are shown as squares. CSN sites with no IMPROVE site within 150 km 

are shown as triangles. These sites were not used in the analysis. ............................................S-11

Figure S.4.1. (a) Seasonal variability for 2005–2008 monthly mean IMPROVE ammonium 

sulfate (AS) mass concentrations. (b) The same as (a), but for the CSN. The color of the upwardpointing triangle refers to the season with the maximum monthly mean concentration, and the 

downward-pointing triangle refers to the season with the minimum monthly mean concentration. 

The size of the triangles refers to the magnitude of the ratio of maximum to minimum monthly 

mean mass concentration. ..........................................................................................................S-13

Figure S.4.2. (a) Seasonal variability for 2005–2008 monthly mean IMPROVE ammonium 

nitrate (AN) mass concentrations. (b) The same as (a), but for the CSN. The color of the 

upward-pointing triangle refers to the season with the maximum monthly mean concentration, 

and the downward-pointing triangle refers to the season with the minimum monthly mean 

concentration. The size of the triangles refers to the magnitude of the ratio of maximum to 

minimum monthly mean mass concentration. ...........................................................................S-14

Figure S.4.3. (a) Seasonal variability for 2005–2008 monthly mean IMPROVE particulate 

organic matter (POM) mass concentrations. (b) The same as (a), but for the CSN. The color of 

the upward-pointing triangle refers to the season with the maximum monthly mean 
ix

IMPROVE REPORT V

concentration, and the downward-pointing triangle refers to the season with the minimum 

monthly mean concentration. The size of the triangles refers to the magnitude of the ratio of 

maximum to minimum monthly mean mass concentration.......................................................S-14

Figure S.4.4. (a) Seasonal variability for 2005–2008 monthly mean IMPROVE light 

absorbing carbon (LAC) mass concentrations. (b) The same as (a), but for the CSN. The color of 

the upward-pointing triangle refers to the season with the maximum monthly mean 

concentration, and the downward-pointing triangle refers to the season with the minimum 

monthly mean concentration. The size of the triangles refers to the magnitude of the ratio of 

maximum to minimum monthly mean mass concentration.......................................................S-15

Figure S.4.5. (a) Seasonal variability for 2005–2008 monthly mean IMPROVE fine soil mass 

concentrations. (b) The same as (a), but for the CSN. The color of the upward-pointing triangle 

refers to the season with the maximum monthly mean concentration, and the downward-pointing 

triangle refers to the season with the minimum monthly mean concentration. The size of the 

triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration..............................................................................................................................S-16

Figure S.4.6. (a) Seasonal variability for 2005–2008 monthly mean IMPROVE PM2.5 

gravimetric fine mass (FM) concentrations. (b) The same as (a), but for the CSN. The color of 

the upward-pointing triangle refers to the season with the maximum monthly mean 

concentration, and the downward-pointing triangle refers to the season with the minimum 

monthly mean concentration. The size of the triangles refers to the magnitude of the ratio of 

maximum to minimum monthly mean mass concentration.......................................................S-17

Figure S.5.1a. Annual mean PM2.5 deciview (dv) for 2005–2008 for rural IMPROVE sites. 

Wavelength corresponds to 550 nm...........................................................................................S-20

Figure S.5.1b. Seasonal variability for 2005–2008 monthly mean IMPROVE deciview (dv) 

light extinction coefficient (bext). The color of the upward-pointing triangle refers to the season 

with the maximum monthly mean concentration, and the downward-pointing triangle refers to 

the season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. .............S-20

Figure S.5.2.1. IMPROVE regional monthly mean (2005–2008) PM2.5 light extinction 

coefficient (bext) fractions for Hawaii, Alaska, and the Virgin Islands. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) is in 

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites, shown as dots. ...........................................S-21

Figure S.5.2.2. IMPROVE regional monthly mean (2005–2008) PM2.5 light extinction 

coefficient (bext) fractions for the eastern United States. The letters on the x-axis correspond to 

the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) is in yellow, 

ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light absorbing 

carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area corresponds to the 

regions that comprise the sites, shown as dots...........................................................................S-22

Figure S.5.2.3. IMPROVE regional monthly mean (2005–2008) PM2.5 light extinction 

coefficient (bext) fractions for the southwestern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) is in 
x

IMPROVE REPORT V

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites, shown as dots. ...........................................S-23

Figure S.5.2.4. IMPROVE regional monthly mean (2005–2008) PM2.5 light extinction 

coefficient (bext) fractions for the northwestern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) is in 

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites, shown as dots. ...........................................S-23

Figure S.6.1.1. Long-term (1989–2008) trends (% yr-1) in average winter sulfate ion mass 

concentrations. Sites with statistically significant trends (p≤0.05) are designated by filled red 

(increasing) and blue (decreasing) triangles. Insignificant trends (p>0.15) are designated by filled 

black triangles. ...........................................................................................................................S-26

Figure S.6.1.2. Short-term (2000–2008) trends (% yr-1) in average spring sulfate ion mass 

concentrations. Sites with statistically significant trends (p≤0.05) are designated by filled red 

(increasing) and blue (decreasing) triangles. Insignificant trends (p>0.15) are designated by filled 

black triangles. ...........................................................................................................................S-27

Figure S.6.2.1. Short-term (2000–2008) trends (% yr-1) in 10th percentile nitrate ion mass 

concentrations. Sites with statistically significant trends (p≤0.05) are designated by filled red 

(increasing) and blue (decreasing) triangles. Insignificant trends (p>0.15) are designated by filled 

black triangles. ...........................................................................................................................S-28

Figure S.6.2.2. Short-term (2000–2008) trends (% yr-1) in 50th percentile nitrate ion mass 

concentrations. Sites with statistically significant trends (p≤0.05) are designated by filled red 

(increasing) and blue (decreasing) triangles. Insignificant trends (p>0.15) are designated by filled 

black triangles. ...........................................................................................................................S-29

Figure S.6.3.1. Long-term (1989–2008) trends (% yr-1) in 10th percentile total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations. Sites with statistically significant 

trends (p≤0.05) are designated by filled red (increasing) and blue (decreasing) triangles. 

Insignificant trends (p>0.15) are designated by filled black triangles.......................................S-30

Figure S.6.4.1. Long-term (1989–2008) trends (% yr-1) in 10th percentile PM2.5 gravimetric 

fine mass (FM) concentrations. Sites with statistically significant trends (p≤0.05) are designated 

by filled red (increasing) and blue (decreasing) triangles. Insignificant trends (p>0.15) are 

designated by filled black triangles............................................................................................S-31

Figure 1.1. Class I areas of the contiguous United States. The shade coding identifies the 

managing agency of each Class I area. ........................................................................................1-2

Figure 1.2. Locations of IMPROVE and IMPROVE protocol sites are shown for all 

discontinued and current sites as of December 2010. The IMPROVE regions used for grouping 

the sites are indicated by shading and bold text. Urban sites included in the IMPROVE network 

for quality assurance purposes are identified by stars. ................................................................ 1-4

Figure 1.3. Schematic view of the IMPROVE sampler showing the four modules with 

separate inlets and pumps. The substrates with analyses performed for each module are also 

shown. ........................................................................................................................................ 1-15
xi

IMPROVE REPORT V

Figure 1.4. Schematic of the version II IMPROVE sampler PM2.5 module. ........................ 1-16

Figure 1.5. Detached screen cassette..................................................................................... 1-30

Figure 1.6. Attached screen cassette. .................................................................................... 1-30

Figure 1.7. Filter sample collected using attached screen cassette. ...................................... 1-32

Figure 1.8. Filter sample collected using detached screen cassette....................................... 1-32

Figure 1.9. Current and discontinued Chemical Speciation Network (CSN) sites (grey and 

orange) operated by the Environmental Protection Agency. Regions are shown as shaded areas 

and bold text. The sites included in the analyses in this report are shown as orange circles..... 1-37

Figure 1.10. Comparisons of 2005–2008 aerosol mass concentration data (μg m-3) for seven 

collocated IMPROVE and CSN sites (see text) for adjusted organic carbon (OC), adjusted light 

absorbing carbon (LAC), ammonium sulfate (AS), ammonium nitrate (AN), soil, sea salt (SS), 

PM2.5 gravimetric fine mass (FM), and PM2.5 reconstructed fine mass (RCFM)...................... 1-43

Figure 2.2.1a. IMPROVE (rural) 2005–2008 PM2.5 ammonium sulfate (AS) annual mean 

mass concentrations (μg m-3). ....................................................................................................2-11

Figure 2.2.1b. IMPROVE and CSN 2005–2008 PM2.5 ammonium sulfate (AS) annual mean 

mass concentrations (μg m-3). .................................................................................................... 2-11

Figure 2.2.1c. IMPROVE (rural) 2005–2008 annual mean percent (%) contributions of 

ammonium sulfate (AS) to PM2.5 reconstructed fine mass (RCFM). ........................................ 2-12

Figure 2.2.1d. IMPROVE and CSN 2005–2008 annual mean percent (%) contributions of 

ammonium sulfate (AS) to PM2.5 reconstructed fine mass (RCFM). ........................................ 2-12

Figure 2.2.2a. IMPROVE (rural) 2005–2008 PM2.5 ammonium nitrate (AN) annual mean 

mass concentrations (μg m-3). .................................................................................................... 2-14

Figure 2.2.2b. IMPROVE and CSN 2005–2008 PM2.5 ammonium nitrate (AN) annual mean 

mass concentrations (μg m-3). .................................................................................................... 2-14

Figure 2.2.2c. IMPROVE (rural) 2005–2008 annual mean percent (%) contributions of 

ammonium nitrate (AN) to PM2.5 reconstructed fine mass (RCFM)......................................... 2-15

Figure 2.2.2d. IMPROVE and CSN 2005–2008 annual mean percent (%) contributions of 

ammonium nitrate (AN) to PM2.5 reconstructed fine mass (RCFM)......................................... 2-15

Figure 2.2.3a. IMPROVE (rural) 2005–2008 PM2.5 particulate organic matter (POM) annual 

mean mass concentrations (μg m-3). .......................................................................................... 2-17

Figure 2.2.3b. IMPROVE and CSN 2005–2008 PM2.5 particulate organic matter (POM) 

annual mean mass concentrations (μg m-3)................................................................................ 2-17

Figure 2.2.3c. IMPROVE (rural) 2005–2008 annual mean percent (%) contributions of 

particulate organic matter (POM) to PM2.5 reconstructed fine mass (RCFM). ......................... 2-18

Figure 2.2.3d. IMPROVE and CSN 2005–2008 annual mean percent (%) contributions of 

particulate organic matter (POM) to PM2.5 reconstructed fine mass (RCFM). ......................... 2-18

Figure 2.2.4a. IMPROVE (rural) 2005–2008 PM2.5 light absorbing carbon (LAC) annual 

mean mass concentrations (μg m-3). .......................................................................................... 2-19
xii

IMPROVE REPORT V

Figure 2.2.4b. IMPROVE and CSN 2005–2008 PM2.5 light absorbing carbon (LAC) annual 

mean mass concentrations (μg m-3). .......................................................................................... 2-20

Figure 2.2.4c. IMPROVE (rural) 2005–2008 annual mean percent (%) contributions of light 

absorbing carbon (LAC) to PM2.5 reconstructed fine mass (RCFM). ....................................... 2-20

Figure 2.2.4d. IMPROVE and CSN 2005–2008 annual mean percent (%) contributions of 

light absorbing carbon (LAC) to PM2.5 reconstructed fine mass (RCFM). ............................... 2-21

Figure 2.2.5a. IMPROVE (rural) 2005–2008 PM2.5 soil annual mean mass concentrations (μg 

m

-3

)............................................................................................................................................. 2-22

Figure 2.2.5b. IMPROVE and CSN 2005–2008 PM2.5 soil annual mean mass concentrations 

(μg m-3). ..................................................................................................................................... 2-23

Figure 2.2.5c. IMPROVE (rural) 2005–2008 annual mean percent (%) contributions of soil to 

PM2.5 reconstructed fine mass (RCFM)..................................................................................... 2-23

Figure 2.2.5d. IMPROVE and CSN 2005–2008 annual mean percent (%) contributions of soil 

to PM2.5 reconstructed fine mass (RCFM)................................................................................. 2-24

Figure 2.2.6a. IMPROVE (rural) 2005–2008 PM2.5 sea salt (SS) annual mean mass 

concentrations (μg m-3). ............................................................................................................. 2-25

Figure 2.2.6b. IMPROVE and CSN 2005–2008 PM2.5 sea salt (SS) annual mean mass 

concentrations (μg m-3). ............................................................................................................. 2-25

Figure 2.2.6c. IMPROVE (rural) 2005–2008 annual mean percent (%) contributions of sea 

salt to PM2.5 reconstructed fine mass (RCFM). ......................................................................... 2-26

Figure 2.2.6d. IMPROVE and CSN 2005–2008 annual mean percent (%) contributions of sea 

salt (SS) to PM2.5 reconstructed fine mass (RCFM). ................................................................. 2-26

Figure 2.2.7a. IMPROVE (rural) 2005–2008 PM2.5 annual mean gravimetric fine mass (FM) 

concentrations (μg m-3). ............................................................................................................. 2-27

Figure 2.2.7b. IMPROVE and CSN 2005–2008 PM2.5 annual mean gravimetric fine mass 

(FM) concentrations (μg m-3)..................................................................................................... 2-28

Figure 2.2.8a. IMPROVE (rural) 2005–2008 PM2.5 annual mean reconstructed fine mass 

(RCFM) concentrations (μg m-3). .............................................................................................. 2-29

Figure 2.2.8.b. IMPROVE and CSN 2005–2008 PM2.5 annual mean reconstructed fine mass 

(RCFM) concentrations (μg m-3). .............................................................................................. 2-29

Figure 2.2.9a. IMPROVE (rural) 2005–2008 PM2.5 annual mean mass difference (dM = FM -

RCFM) between PM2.5 gravimetric fine mass (FM) and reconstructed fine mass (RCFM) (μg m3

)................................................................................................................................................. 2-30

Figure 2.2.9b. IMPROVE and CSN 2005–2008 PM2.5 annual mean difference (dM = FM -

RCFM) between PM2.5 gravimetric fine mass (FM) and reconstructed fine mass (RCFM) (μg m3

)................................................................................................................................................. 2-31

Figure 2.2.10. IMPROVE (rural) 2005–2008 annual mean coarse mass (CM = PM10 - PM2.5) 

(μg m-3). ..................................................................................................................................... 2-32

Figure 2.2.11a. IMPROVE (rural) 2005–2008 annual mean PM10 mass (μg m-3)................ 2-33
xiii

IMPROVE REPORT V

Figure 2.2.11b. IMPROVE (rural) and EPA 2005–2008 annual mean PM10 mass (μg m-3).2-33

Figure 3.1. Humidification factor (f(RH)) as a function of relative humidity (RH) A lognormal 

ammonium sulfate mass size distribution with a geometric mass mean diameter of 0.3 μm and a 

geometric standard deviation of 2.0 was assumed. A wavelength of 550 nm was used. ............3-4

Figure 3.2a. PM2.5 reconstructed ambient annual mean light extinction coefficient for 

ammonium sulfate (bext_AS, Mm-1) for 2005–2008 for rural IMPROVE sites. The “modified 

original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm.......... 3-6

Figure 3.2b. PM2.5 reconstructed ambient annual mean light extinction coefficient for 

ammonium sulfate (bext_AS, Mm-1) for 2005–2008 for rural IMPROVE and urban CSN sites. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................... 3-6

Figure 3.2c. Annual mean percent contribution (%) of ambient ammonium sulfate (AS) light 

extinction coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural 

IMPROVE sites. The “modified original” IMPROVE algorithm was used (see text). Wavelength 

corresponds to 550 nm................................................................................................................. 3-7

Figure 3.2d. Annual mean percent contribution (%) of ambient ammonium sulfate (AS) light 

extinction coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural 

IMPROVE and urban CSN sites. The “modified original” IMPROVE algorithm was used (see 

text). Wavelength corresponds to 550 nm. .................................................................................. 3-7

Figure 3.3a. PM2.5 reconstructed ambient annual mean light extinction coefficient for 

ammonium nitrate (bext_AN, Mm-1) for 2005–2008 for rural IMPROVE sites. The “modified 

original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm.......... 3-9

Figure 3.3b. PM2.5 reconstructed ambient annual mean light extinction coefficient for 

ammonium nitrate (bext_AN, Mm-1) for 2005–2008 for rural IMPROVE and urban CSN sites. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................... 3-9

Figure 3.3c. Annual mean percent contribution (%) of ambient ammonium nitrate (AN) light 

extinction coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural 

IMPROVE sites. The “modified original” IMPROVE algorithm was used (see text). Wavelength 

corresponds to 550 nm............................................................................................................... 3-10

Figure 3.3d. Annual mean percent contribution (%) of ambient ammonium nitrate (AN) light 

extinction coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural 

IMPROVE and urban CSN sites. The “modified original” IMPROVE algorithm was used (see 

text). Wavelength corresponds to 550 nm. ................................................................................ 3-10

Figure 3.4a. PM2.5 reconstructed ambient annual mean light extinction coefficient for 

particulate organic matter (POM) (bext_POM, Mm-1) for 2005–2008 for rural IMPROVE sites. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................. 3-12

Figure 3.4b. PM2.5 reconstructed ambient annual mean light extinction coefficient for 

particulate organic matter (POM) (bext_POM, Mm-1) for 2005–2008 for rural IMPROVE and urban 

CSN sites. The “modified original” IMPROVE algorithm was used (see text). Wavelength 

corresponds to 550 nm............................................................................................................... 3-12
xiv

IMPROVE REPORT V

Figure 3.4c. Annual mean percent contribution (%) of ambient particulate organic matter 

(POM) light extinction coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for 

rural IMPROVE sites. The “modified original” IMPROVE algorithm was used (see text). 

Wavelength corresponds to 550 nm........................................................................................... 3-13

Figure 3.4d. Annual mean percent contribution (%) of ambient particulate organic matter 

(POM) light extinction coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for 

rural IMPROVE and urban CSN sites. The “modified original” IMPROVE algorithm was used 

(see text). Wavelength corresponds to 550 nm.......................................................................... 3-13

Figure 3.5a. PM2.5 reconstructed ambient annual mean light extinction coefficient for light 

absorbing carbon (bext_LAC, Mm-1) for 2005–2008 for rural IMPROVE sites. The “modified 

original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm........ 3-14

Figure 3.5b. PM2.5 reconstructed ambient annual mean light extinction coefficient for light 

absorbing carbon (bext_LAC, Mm-1) for 2005–2008 for rural IMPROVE and urban CSN sites. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................. 3-15

Figure 3.5c. Annual mean percent contribution (%) of ambient light absorbing carbon (LAC) 

light extinction coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural 

IMPROVE sites. The “modified original” IMPROVE algorithm was used (see text). Wavelength 

corresponds to 550 nm............................................................................................................... 3-15

Figure 3.5d. Annual mean percent contribution (%) of ambient light absorbing carbon (LAC) 

light extinction coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural 

IMPROVE and urban CSN sites. The “modified original” IMPROVE algorithm was used (see 

text). Wavelength corresponds to 550 nm. ................................................................................ 3-16

Figure 3.6a. PM2.5 reconstructed ambient annual mean light extinction coefficient for soil 

(bext_soil, Mm-1) for 2005–2008 for rural IMPROVE sites. The “modified original” IMPROVE 

algorithm was used (see text). Wavelength corresponds to 550 nm.......................................... 3-17

Figure 3.6b. PM2.5 reconstructed ambient annual mean light extinction coefficient for soil 

(bext_soil, Mm-1) for 2005–2008 for rural IMPROVE and urban CSN sites. The “modified 

original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm........ 3-17

Figure 3.6c. Annual mean percent contribution (%) of ambient soil light extinction coefficient 

(bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural IMPROVE sites. The “modified 

original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm........ 3-18

Figure 3.6d. Annual mean percent contribution (%) of ambient soil light extinction coefficient 

(bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural IMPROVE and urban CSN 

sites. The “modified original” IMPROVE algorithm was used (see text). Wavelength 

corresponds to 550 nm............................................................................................................... 3-18

Figure 3.7a. PM2.5 reconstructed ambient annual mean light extinction coefficient for sea salt 

(bext_SS, Mm-1) for 2005–2008 for rural IMPROVE sites. The “modified original” IMPROVE 

algorithm was used (see text). Wavelength corresponds to 550 nm.......................................... 3-19

Figure 3.7b. PM2.5 reconstructed ambient annual mean light extinction coefficient for sea salt 

(bext_SS, Mm-1) for 2005–2008 for rural IMPROVE and urban CSN sites. The “modified original” 

IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm....................... 3-20
xv

IMPROVE REPORT V

Figure 3.7c. Annual mean percent contribution (%) of ambient sea salt (SS) light extinction 

coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural IMPROVE sites. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................. 3-20

Figure 3.7d. Annual mean percent contribution (%) of ambient sea salt (SS) light extinction 

coefficient (bext) to PM2.5 reconstructed aerosol bext for 2005–2008 for rural IMPROVE and 

urban CSN sites. The “modified original” IMPROVE algorithm was used (see text). Wavelength 

corresponds to 550 nm............................................................................................................... 3-21

Figure 3.8a. PM2.5 reconstructed annual mean light extinction coefficient for ambient aerosol 

(bext_aer, Mm-1) for 2005–2008 for rural IMPROVE sites. The “modified original” IMPROVE 

algorithm was used (see text). Wavelength corresponds to 550 nm.......................................... 3-22

Figure 3.8b. PM2.5 reconstructed annual mean light extinction coefficient for ambient aerosol 

(bext_aer, Mm-1) for 2005–2008 for rural IMPROVE and urban CSN sites. The “modified original” 

IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm....................... 3-22

Figure 3.9a. Annual mean light extinction coefficient for coarse mass (bext_CM, Mm-1) for 

2005–2008 for rural IMPROVE sites. The “modified original” IMPROVE algorithm was used 

(see text). Wavelength corresponds to 550 nm.......................................................................... 3-23

Figure 3.9b. Annual mean percent contribution (%) of coarse mass (CM) light extinction 

coefficient to total reconstructed aerosol bext for 2005–2008 for rural IMPROVE sites. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. Rayleigh scattering was not included in total bext............................................................... 3-24

Figure 3.10. Annual mean PM2.5 deciview (dv) for 2005–2008 for rural IMPROVE sites. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................. 3-25

Figure 4.1.1. IMPROVE 2005–2008 regional monthly mean PM2.5 mass concentrations (μg 

m

-3

) for the eastern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots..............................................................................................4-3

Figure 4.1.2. IMPROVE 2005–2008 regional monthly mean PM2.5 mass concentrations (μg m3

) for the northwestern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots.............................................................................................. 4-4

Figure 4.1.3. IMPROVE 2005–2008 regional monthly mean PM2.5 mass concentrations (μg m3

) for the southwestern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots.............................................................................................. 4-5
xvi

IMPROVE REPORT V

Figure 4.1.4. IMPROVE 2005–2008 regional monthly mean PM2.5 mass concentrations (μg m

-

3

) for Hawaii, Alaska, and the Virgin Islands. The letters on the x-axis correspond to the month 

and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate 

(AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, 

soil in brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots...................................................................................... 4-6

Figure 4.1.5. Seasonal variability for IMPROVE 2005–2008 monthly mean ammonium 

sulfate (AS) mass concentrations. The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............... 4-7

Figure 4.1.6. CSN 2005–2008 regional monthly mean PM2.5 mass concentrations (μg m-3) for 

the eastern United States. The letters on the x-axis correspond to the month and “A” corresponds 

to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in red, particulate 

organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in brown, and sea 

salt in blue. The shaded area corresponds to the regions that comprise the sites used in the 

analysis, shown as dots. ............................................................................................................... 4-8

Figure 4.1.7. CSN 2005–2008 regional monthly mean PM2.5 mass concentrations (μg m-3) for 

the southwestern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots.............................................................................................. 4-9

Figure 4.1.8. CSN 2005–2008 regional monthly mean PM2.5 mass concentrations (μg m-3) for 

the northwestern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots............................................................................................ 4-10

Figure 4.1.9. CSN 2005–2008 regional monthly mean PM2.5 mass concentrations (μg m-3) for 

Hawaii and Alaska. The letters on the x-axis correspond to the month and “A” corresponds to 

“annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in red, particulate 

organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in brown, and sea 

salt in blue. The shaded area corresponds to the regions that comprise the sites used in the 

analysis, shown as dots. ............................................................................................................. 4-11

Figure 4.1.10. Seasonal variability for CSN 2005–2008 monthly mean ammonium sulfate 

(AS) mass concentrations. The color of the upward pointing triangle refers to the season with the 

maximum monthly mean concentration and the downward pointing triangle refers to the season 

with the minimum monthly mean concentration. The size of the triangles refers to the magnitude 

of the ratio of maximum to minimum monthly mean mass concentration. ............................... 4-12

Figure 4.1.11. IMPROVE 2005–2008 regional monthly mean PM2.5 reconstructed fine mass 

fractions for the eastern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 
xvii

IMPROVE REPORT V

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots............................................................................................ 4-13

Figure 4.1.12. IMPROVE 2005–2008 regional monthly mean PM2.5 reconstructed fine mass 

fractions for the northwestern United States. The letters on the x-axis correspond to the month 

and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate 

(AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, 

soil in brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 4-14

Figure 4.1.13. IMPROVE 2005–2008 regional monthly mean PM2.5 reconstructed fine mass 

fractions for the southwestern United States. The letters on the x-axis correspond to the month 

and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate 

(AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, 

soil in brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 4-15

Figure 4.1.14. IMPROVE 2005–2008 regional monthly mean PM2.5 reconstructed fine mass 

fractions for Hawaii, Alaska,and the Virgin Islands. The letters on the x-axis correspond to the 

month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium 

nitrate (AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in 

black, soil in brown, and sea salt in blue. The shaded area corresponds to the regions that 

comprise the sites used in the analysis, shown as dots. ............................................................. 4-16

Figure 4.1.15. Seasonal variability for IMPROVE 2005–2008 monthly mean ammonium 

sulfate (AS) reconstructed fine mass fractions. The color of the upward pointing triangle refers to 

the season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 4-17

Figure 4.1.16. CSN 2005–2008 regional monthly mean PM2.5 reconstructed fine mass 

fractions for the eastern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots............................................................................................ 4-18

Figure 4.1.17. CSN 2005–2008 regional monthly mean PM2.5 reconstructed fine mass 

fractions for the northwestern United States. The letters on the x-axis correspond to the month 

and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate 

(AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, 

soil in brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 4-19

Figure 4.1.18. CSN 2005–2008 regional monthly mean PM2.5 reconstructed fine mass 

fractions for the southwestern United States. The letters on the x-axis correspond to the month 

and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate 

(AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, 
xviii

IMPROVE REPORT V

soil in brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 4-20

Figure 4.1.19. CSN 2005–2008 regional monthly mean PM2.5 reconstructed fine mass 

fractions for Hawaii and Alaska. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots............................................................................................ 4-21

Figure 4.1.20. Seasonal variability for CSN 2005–2008 monthly mean ammonium sulfate 

(AS) reconstructed fine mass fractions. The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 4-22

Figure 4.2.1. Seasonal variability for IMPROVE 2005–2008 monthly mean ammonium nitrate 

(AN) mass concentrations. The color of the upward pointing triangle refers to the season with the 

maximum monthly mean concentration and the downward pointing triangle refers to the season 

with the minimum monthly mean concentration. The size of the triangles refers to the magnitude 

of the ratio of maximum to minimum monthly mean mass concentration. ............................... 4-23

Figure 4.2.2. Seasonal variability for CSN 2005–2008 monthly mean ammonium nitrate (AN) 

mass concentrations. The color of the upward pointing triangle refers to the season with the 

maximum monthly mean concentration and the downward pointing triangle refers to the season 

with the minimum monthly mean concentration. The size of the triangles refers to the magnitude 

of the ratio of maximum to minimum monthly mean mass concentration. ............................... 4-24

Figure 4.2.3. Seasonal variability for IMPROVE 2005–2008 monthly mean ammonium nitrate 

(AN) reconstructed fine mass fractions. The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 4-25

Figure 4.2.4. Seasonal variability for CSN 2005–2008 monthly mean ammonium nitrate (AN) 

reconstructed fine mass fractions. The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 4-26

Figure 4.3.1. Seasonal variability for IMPROVE 2005–2008 monthly mean particulate 

organic matter (POM) mass concentrations. The color of the upward pointing triangle refers to 

the season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 4-27

Figure 4.3.2. Seasonal variability for CSN 2005–2008 monthly mean particulate organic 

matter (POM) mass concentrations. The color of the upward pointing triangle refers to the season 
xix

IMPROVE REPORT V

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 4-28

Figure 4.3.3. Seasonal variability for IMPROVE 2005–2008 monthly mean particulate 

organic matter (POM) reconstructed fine mass fractions. The color of the upward pointing 

triangle refers to the season with the maximum monthly mean concentration and the downward 

pointing triangle refers to the season with the minimum monthly mean concentration. The size of 

the triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 4-29

Figure 4.3.4. Seasonal variability for CSN 2005–2008 monthly mean particulate organic 

matter (POM) reconstructed fine mass fractions. The color of the upward pointing triangle refers 

to the season with the maximum monthly mean concentration and the downward pointing 

triangle refers to the season with the minimum monthly mean concentration. The size of the 

triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 4-30

Figure 4.4.1. Seasonal variability for IMPROVE 2005–2008 monthly mean light absorbing 

carbon (LAC) mass concentrations. The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 4-31

Figure 4.4.2. Seasonal variability for CSN 2005–2008 monthly mean light absorbing carbon 

(LAC) mass concentrations. The color of the upward pointing triangle refers to the season with 

the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 4-32

Figure 4.4.3. Seasonal variability for IMPROVE 2005–2008 monthly mean light absorbing 

carbon (LAC) reconstructed fine mass fractions. The color of the upward pointing triangle refers 

to the season with the maximum monthly mean concentration and the downward pointing 

triangle refers to the season with the minimum monthly mean concentration. The size of the 

triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 4-33

Figure 4.4.4. Seasonal variability for CSN 2005–2008 monthly mean light absorbing carbon 

(LAC) reconstructed fine mass fractions. The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 4-34

Figure 4.5.1. Seasonal variability for IMPROVE 2005–2008 monthly mean fine soil mass 

concentrations. The color of the upward pointing triangle refers to the season with the maximum 

monthly mean concentration and the downward pointing triangle refers to the season with the 

minimum monthly mean concentration. The size of the triangles refers to the magnitude of the 

ratio of maximum to minimum monthly mean mass concentration. ......................................... 4-35
xx

IMPROVE REPORT V

Figure 4.5.2. Seasonal variability for CSN 2005–2008 monthly mean fine soil mass 

concentrations. The color of the upward pointing triangle refers to the season with the maximum 

monthly mean concentration and the downward pointing triangle refers to the season with the 

minimum monthly mean concentration. The size of the triangles refers to the magnitude of the 

ratio of maximum to minimum monthly mean mass concentration. ......................................... 4-36

Figure 4.5.3. Seasonal variability for IMPROVE 2005–2008 monthly mean fine soil 

reconstructed fine mass fractions. The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 4-37

Figure 4.5.4. Seasonal variability for CSN 2005–2008 monthly mean fine soil reconstructed 

fine mass fractions. The color of the upward pointing triangle refers to the season with the 

maximum monthly mean concentration and the downward pointing triangle refers to the season 

with the minimum monthly mean concentration. The size of the triangles refers to the magnitude 

of the ratio of maximum to minimum monthly mean mass concentration. ............................... 4-38

Figure 4.6.1. Seasonal variability for IMPROVE 2005–2008 monthly mean sea salt (SS) mass 

concentrations. The color of the upward pointing triangle refers to the season with the maximum 

monthly mean concentration and the downward pointing triangle refers to the season with the 

minimum monthly mean concentration. The size of the triangles refers to the magnitude of the 

ratio of maximum to minimum monthly mean mass concentration. ......................................... 4-39

Figure 4.6.2. Seasonal variability for CSN 2005–2008 monthly mean sea salt (SS) mass 

concentrations. The color of the upward pointing triangle refers to the season with the maximum 

monthly mean concentration and the downward pointing triangle refers to the season with the 

minimum monthly mean concentration. The size of the triangles refers to the magnitude of the 

ratio of maximum to minimum monthly mean mass concentration. ......................................... 4-40

Figure 4.6.3. Seasonal variability for IMPROVE 2005–2008 monthly mean sea salt (SS) 

reconstructed fine mass fractions. The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 4-41

Figure 4.6.4. Seasonal variability for CSN 2005–2008 monthly mean sea salt (SS) 

reconstructed fine mass fractions. The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 4-42

Figure 4.7.1. Seasonal variability for IMPROVE 2005–2008 monthly mean PM2.5 gravimetric 

fine mass (FM) concentrations. The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 4-43

Figure 4.7.2. Seasonal variability for CSN 2005–2008 monthly mean PM2.5 gravimetric fine 

mass (FM) concentrations. The color of the upward pointing triangle refers to the season with the 

maximum monthly mean concentration and the downward pointing triangle refers to the season 
xxi

IMPROVE REPORT V

with the minimum monthly mean concentration. The size of the triangles refers to the magnitude 

of the ratio of maximum to minimum monthly mean mass concentration. ............................... 4-44

Figure 4.8.1. IMPROVE 2005–2008 regional monthly mean coarse mass concentrations (μg 

m

-3

) for the northwestern United States. The letters on the x-axis correspond to the month and 

“A” corresponds to “annual” mean. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 4-45

Figure 4.8.2. IMPROVE 2005–2008 regional monthly mean coarse mass concentrations (μg 

m

-3

) for the southwestern United States. The letters on the x-axis correspond to the month and 

“A” corresponds to “annual” mean. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 4-46

Figure 4.8.3. IMPROVE 2005–2008 regional monthly mean coarse mass concentrations (μg 

m

-3

) for the eastern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 4-47

Figure 4.8.4. IMPROVE 2005–2008 regional monthly mean coarse mass concentrations (μg 

m

-3

) for OCONUS U.S. The letters on the x-axis correspond to the month and “A” corresponds 

to “annual” mean. The shaded area corresponds to the regions that comprise the sites used in the 

analysis, shown as dots. ............................................................................................................. 4-48

Figure 4.8.5. Seasonal variability for IMPROVE 2005–2008 monthly mean coarse mass (CM) 

concentrations. The color of the upward pointing triangle refers to the season with the maximum 

monthly mean concentration and the downward pointing triangle refers to the season with the 

minimum monthly mean concentration. The size of the triangles refers to the magnitude of the 

ratio of maximum to minimum monthly mean mass concentration. ......................................... 4-49

Figure 5.1.1. IMPROVE 2005–2008 regional monthly mean PM2.5 reconstructed light 

extinction coefficients (bext, Mm-1) for the eastern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in 

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites used in the analysis, shown as dots. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550

nm. ...............................................................................................................................................5-2

Figure 5.1.2. IMPROVE 2005–2008 regional monthly mean PM2.5 reconstructed light 

extinction coefficients (bext, Mm-1) for the northwestern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in 

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites used in the analysis, shown as dots. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................... 5-3

Figure 5.1.3. IMPROVE 2005–2008 regional monthly mean PM2.5 reconstructed light 

extinction coefficients (bext, Mm-1) for the southwestern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in 

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 
xxii

IMPROVE REPORT V

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites used in the analysis, shown as dots. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................... 5-4

Figure 5.1.4. IMPROVE 2005–2008 regional monthly mean PM2.5 reconstructed light 

extinction coefficients (bext, Mm-1) for Hawaii, Alaska, and the Virgin Islands. The letters on the 

x-axis correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) 

in yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites used in the analysis, shown as dots. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................... 5-5

Figure 5.1.5. Seasonal variability for 2005–2008 monthly mean regional IMPROVE 

ammonium sulfate (AS) light extinction coefficients (bext). The color of the upward pointing 

triangle refers to the season with the maximum monthly mean concentration and the downward 

pointing triangle refers to the season with the minimum monthly mean concentration. The size of 

the triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration................................................................................................................................ 5-6

Figure 5.1.6. CSN 2005–2008 regional monthly mean PM2.5 reconstructed light extinction 

coefficients (bext, Mm-1) for the southwestern United States. The letters on the x-axis correspond 

to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, 

ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light absorbing 

carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area corresponds to the 

regions that comprise the sites used in the analysis, shown as dots. The “modified original” 

IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm......................... 5-7

Figure 5.1.7. CSN 2005–2008 regional monthly mean PM2.5 reconstructed light extinction 

coefficients (bext, Mm-1) for the northwestern United States. The letters on the x-axis correspond 

to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, 

ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light absorbing 

carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area corresponds to the 

regions that comprise the sites used in the analysis, shown as dots. The “modified original” 

IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm......................... 5-8

Figure 5.1.8. CSN 2005–2008 regional monthly mean reconstructed light extinction 

coefficients (bext, Mm-1) for the eastern United States. The letters on the x-axis correspond to the 

month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium 

nitrate (AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in 

black, soil in brown, and sea salt in blue. The shaded area corresponds to the regions that 

comprise the sites used in the analysis, shown as dots. The “modified original” IMPROVE 

algorithm was used (see text). Wavelength corresponds to 550 nm............................................ 5-9

Figure 5.1.9. CSN 2005–2008 regional monthly mean PM2.5 reconstructed light extinction 

coefficients (bext, Mm-1) for Hawaii and Alaska. The letters on the x-axis correspond to the 

month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium 

nitrate (AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in 

black, soil in brown, and sea salt in blue. The shaded area corresponds to the regions that 
xxiii

IMPROVE REPORT V

comprise the sites used in the analysis, shown as dots. The “modified original” IMPROVE 

algorithm was used (see text). Wavelength corresponds to 550 nm.......................................... 5-10

Figure 5.1.10. Seasonal variability for 2005–2008 monthly mean regional CSN ammonium 

sulfate (AS) light extinction coefficients (bext). The color of the upward pointing triangle refers to 

the season with the maximum monthly mean concentration and the downward pointing triangle

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-11

Figure 5.1.11. IMPROVE 2005–2008 regional monthly mean PM2.5 light extinction 

coefficient (bext) fractions for Hawaii, Alaska, and the Virgin Islands. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in 

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites used in the analysis, shown as dots. ........... 5-12

Figure 5.1.12. IMPROVE 2005–2008 regional monthly mean PM2.5 light extinction 

coefficient (bext) fractions for the eastern United States. The letters on the x-axis correspond to 

the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, 

ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light absorbing 

carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area corresponds to the 

regions that comprise the sites used in the analysis, shown as dots. ......................................... 5-13

Figure 5.1.13. IMPROVE 2005–2008 regional monthly mean PM2.5 light extinction 

coefficient (bext) fractions for the southwestern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in 

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites used in the analysis, shown as dots. ........... 5-14

Figure 5.1.14. IMPROVE 2005–2008 regional monthly mean PM2.5 light extinction 

coefficient (bext) fractions for the northwestern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in 

yellow, ammonium nitrate (AN) in red, particulate organic matter (POM) in green, light 

absorbing carbon (LAC) in black, soil in brown, and sea salt in blue. The shaded area 

corresponds to the regions that comprise the sites used in the analysis, shown as dots. ........... 5-15

Figure 5.1.15. Seasonal variability for IMPROVE 2005–2008 monthly mean regional 

ammonium sulfate (AS) light extinction coefficient (bext) fractions. The color of the upward 

pointing triangle refers to the season with the maximum monthly mean concentration and the 

downward pointing triangle refers to the season with the minimum monthly mean concentration. 

The size of the triangles refers to the magnitude of the ratio of maximum to minimum monthly 

mean mass concentration. .......................................................................................................... 5-16

Figure 5.1.16. CSN 2005–2008 regional monthly mean PM2.5 light extinction coefficient (bext) 

fractions for the eastern United States. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 
xxiv

IMPROVE REPORT V

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots............................................................................................ 5-17

Figure 5.1.17. CSN 2005–2008 regional monthly mean PM2.5 light extinction coefficient (bext) 

fractions for the northwestern United States. The letters on the x-axis correspond to the month 

and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate 

(AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, 

soil in brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 5-18

Figure 5.1.18. CSN 2005–2008 regional monthly mean PM2.5 light extinction coefficient (bext) 

fractions for the southwestern United States. The letters on the x-axis correspond to the month 

and “A” corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate 

(AN) in red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, 

soil in brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the 

sites used in the analysis, shown as dots.................................................................................... 5-19

Figure 5.1.19. CSN 2005–2008 regional monthly mean PM2.5 light extinction coefficient (bext) 

fractions for Hawaii and Alaska. The letters on the x-axis correspond to the month and “A” 

corresponds to “annual” mean. Ammonium sulfate (AS) in yellow, ammonium nitrate (AN) in 

red, particulate organic matter (POM) in green, light absorbing carbon (LAC) in black, soil in 

brown, and sea salt in blue. The shaded area corresponds to the regions that comprise the sites 

used in the analysis, shown as dots............................................................................................ 5-20

Figure 5.1.20. Seasonal variability for CSN 2005–2008 monthly mean regional ammonium 

sulfate (AS) light extinction coefficient (bext) fractions. The color of the upward pointing triangle 

refers to the season with the maximum monthly mean concentration and the downward pointing 

triangle refers to the season with the minimum monthly mean concentration. The size of the 

triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 5-21

Figure 5.2.1. Seasonal variability for IMPROVE 2005–2008 monthly mean regional 

ammonium nitrate (AN) light extinction coefficients (bext). The color of the upward pointing 

triangle refers to the season with the maximum monthly mean concentration and the downward 

pointing triangle refers to the season with the minimum monthly mean concentration. The size of 

the triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 5-22

Figure 5.2.2. Seasonal variability for CSN 2005–2008 monthly mean regional ammonium 

nitrate (AN) light extinction coefficients (bext). The color of the upward pointing triangle refers to 

the season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-24

Figure 5.2.3. Seasonal variability for IMPROVE 2005–2008 monthly mean regional 

ammonium nitrate (AN) light extinction coefficient (bext) fractions. The color of the upward 

pointing triangle refers to the season with the maximum monthly mean concentration and the 

downward pointing triangle refers to the season with the minimum monthly mean concentration. 
xxv

IMPROVE REPORT V

The size of the triangles refers to the magnitude of the ratio of maximum to minimum monthly 

mean mass concentration. .......................................................................................................... 5-25

Figure 5.2.4. Seasonal variability for CSN 2005–2008 monthly mean regional ammonium 

nitrate (AN) light extinction coefficient (bext) fractions. The color of the upward pointing triangle 

refers to the season with the maximum monthly mean concentration and the downward pointing 

triangle refers to the season with the minimum monthly mean concentration. The size of the 

triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 5-26

Figure 5.3.1. Seasonal variability for IMPROVE 2005–2008 monthly mean regional 

particulate organic matter (POM) light extinction coefficients (bext). The color of the upward 

pointing triangle refers to the season with the maximum monthly mean concentration and the 

downward pointing triangle refers to the season with the minimum monthly mean concentration. 

The size of the triangles refers to the magnitude of the ratio of maximum to minimum monthly 

mean mass concentration. .......................................................................................................... 5-28

Figure 5.3.2. Seasonal variability for CSN 2005–2008 monthly mean regional particulate 

organic matter (POM) light extinction coefficients (bext). The color of the upward pointing 

triangle refers to the season with the maximum monthly mean concentration and the downward 

pointing triangle refers to the season with the minimum monthly mean concentration. The size of 

the triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 5-29

Figure 5.3.3. Seasonal variability for IMPROVE 2005–2008 monthly mean regional 

particulate organic matter (POM) light extinction coefficient (bext) fractions. The color of the 

upward pointing triangle refers to the season with the maximum monthly mean concentration 

and the downward pointing triangle refers to the season with the minimum monthly mean 

concentration. The size of the triangles refers to the magnitude of the ratio of maximum to 

minimum monthly mean mass concentration. ........................................................................... 5-30

Figure 5.3.4. Seasonal variability for CSN 2005–2008 monthly mean regional particulate 

organic matter (POM) light extinction coefficient (bext) fractions. The color of the upward 

pointing triangle refers to the season with the maximum monthly mean concentration and the 

downward pointing triangle refers to the season with the minimum monthly mean concentration. 

The size of the triangles refers to the magnitude of the ratio of maximum to minimum monthly 

mean mass concentration. .......................................................................................................... 5-31

Figure 5.4.1. Seasonal variability for IMPROVE 2005–2008 monthly mean regional light 

absorbing carbon (LAC) light extinction coefficients (bext). The color of the upward pointing 

triangle refers to the season with the maximum monthly mean concentration and the downward 

pointing triangle refers to the season with the minimum monthly mean concentration. The size of 

the triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 5-33

Figure 5.4.2. Seasonal variability for CSN 2005–2008 monthly mean regional light absorbing 

carbon (LAC) light extinction coefficients (bext). The color of the upward pointing triangle refers 

to the season with the maximum monthly mean concentration and the downward pointing 

triangle refers to the season with the minimum monthly mean concentration. The size of the 
xxvi

IMPROVE REPORT V

triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 5-34

Figure 5.4.3. Seasonal variability for IMPROVE 2005–2008 monthly mean regional light 

absorbing carbon (LAC) light extinction coefficient (bext) fractions. The color of the upward 

pointing triangle refers to the season with the maximum monthly mean concentration and the 

downward pointing triangle refers to the season with the minimum monthly mean concentration. 

The size of the triangles refers to the magnitude of the ratio of maximum to minimum monthly 

mean mass concentration. .......................................................................................................... 5-35

Figure 5.4.4. Seasonal variability for CSN 2005–2008 monthly mean regional light absorbing 

carbon (LAC) light extinction coefficient (bext) fractions. The color of the upward pointing 

triangle refers to the season with the maximum monthly mean concentration and the downward 

pointing triangle refers to the season with the minimum monthly mean concentration. The size of 

the triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 5-36

Figure 5.5.1. Seasonal variability for IMPROVE 2005–2008 monthly mean regional soil light 

extinction coefficients (bext). The color of the upward pointing triangle refers to the season with 

the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 5-38

Figure 5.5.2. Seasonal variability for CSN 2005–2008 monthly mean regional soil light 

extinction coefficients (bext). The color of the upward pointing triangle refers to the season with 

the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 5-39

Figure 5.5.3. Seasonal variability for IMPROVE 2005–2008 monthly mean regional soil light 

extinction coefficient (bext) fractions. The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-40

Figure 5.5.4. Seasonal variability for CSN 2005–2008 monthly mean regional soil light 

extinction coefficient (bext) fractions. The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-42

Figure 5.6.1. Seasonal variability for IMPROVE 2005–2008 monthly mean regional sea salt 

(SS) light extinction coefficients (bext). The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-43
xxvii

IMPROVE REPORT V

Figure 5.6.2. Seasonal variability for CSN 2005–2008 monthly mean regional sea salt (SS) 

light extinction coefficients (bext). The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 5-44

Figure 5.6.3. Seasonal variability for IMPROVE 2005–2008 monthly mean regional sea salt 

(SS) light extinction coefficients (bext) fraction. The color of the upward pointing triangle refers 

to the season with the maximum monthly mean concentration and the downward pointing 

triangle refers to the season with the minimum monthly mean concentration. The size of the 

triangles refers to the magnitude of the ratio of maximum to minimum monthly mean mass 

concentration.............................................................................................................................. 5-45

Figure 5.6.4. Seasonal variability for CSN 2005–2008 monthly mean regional sea salt (SS) 

light extinction coefficient (bext) fractions. The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-46

Figure 5.7.1. Seasonal variability for IMPROVE 2005–2008 monthly mean regional PM2.5

aerosol light extinction coefficients (bext). The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-47

Figure 5.7.2. Seasonal variability for CSN 2005–2008 monthly mean regional PM2.5 aerosol 

light extinction coefficients (bext). The color of the upward pointing triangle refers to the season 

with the maximum monthly mean concentration and the downward pointing triangle refers to the 

season with the minimum monthly mean concentration. The size of the triangles refers to the 

magnitude of the ratio of maximum to minimum monthly mean mass concentration. ............. 5-48

Figure 5.8.1. IMPROVE 2005–2008 regional monthly mean coarse mass reconstructed light 

extinction coefficients (bext, Mm-1) for Hawaii, Alaska and the Virgin Islands. The letters on the 

x-axis correspond to the month and “A” corresponds to “annual” mean. The shaded area 

corresponds to the regions that comprise the sites used in this analysis, shown as dots. The 

“modified original” IMPROVE algorithm was used (see text). Wavelength corresponds to 550 

nm. ............................................................................................................................................. 5-49

Figure 5.8.2. IMPROVE 2005–2008 regional monthly mean coarse mass reconstructed light 

extinction coefficients (bext, Mm-1) for the northwestern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. The shaded area corresponds to 

the regions that comprise the sites used in this analysis, shown as dots. The “modified original” 

IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm....................... 5-49

Figure 5.8.3. IMPROVE 2005–2008 regional monthly mean coarse mass reconstructed light

extinction coefficients (bext, Mm-1) for the southwestern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. The shaded area corresponds to 
xxviii

IMPROVE REPORT V

the regions that comprise the sites used in this analysis, shown as dots. The “modified original” 

IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm....................... 5-50

Figure 5.8.4. IMPROVE 2005–2008 regional monthly mean coarse mass reconstructed light 

extinction coefficients (bext, Mm-1) for the eastern United States. The letters on the x-axis 

correspond to the month and “A” corresponds to “annual” mean. The shaded area corresponds to 

the regions that comprise the sites used in this analysis, shown as dots. The “modified original” 

IMPROVE algorithm was used (see text). Wavelength corresponds to 550 nm....................... 5-51

Figure 5.8.5. Seasonal variability for IMPROVE 2005–2008 monthly mean regional coarse 

mass (CM) light extinction coefficients (bext). The color of the upward pointing triangle refers to 

the season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-52

Figure 5.9.1. Seasonal variability for IMPROVE 2005–2008 monthly mean regional deciview 

(dv) light extinction coefficients (bext). The color of the upward pointing triangle refers to the 

season with the maximum monthly mean concentration and the downward pointing triangle 

refers to the season with the minimum monthly mean concentration. The size of the triangles 

refers to the magnitude of the ratio of maximum to minimum monthly mean mass concentration.

.................................................................................................................................................... 5-53

Figure 6.1.1. Long-term (1989–2008) trends (% yr-1) in 10th percentile sulfate ion mass 

concentrations. .............................................................................................................................6-4

Figure 6.1.2. Long-term (1989–2008) trends (% yr-1) in average winter sulfate ion mass 

concentrations. ............................................................................................................................. 6-4

Figure 6.1.3. Average winter sulfate ion mass concentrations (μg m-3) for Denali, Alaska 

(DENA1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (s), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. .......................................................................... 6-5

Figure 6.1.4. Long-term (1989–2008) trends (% yr-1) in 90th percentile sulfate ion mass 

concentrations. ............................................................................................................................. 6-5

Figure 6.1.5. 90th percentile sulfate ion mass concentrations (μg m-3) for Big Bend, Texas 

(BIBE1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (s), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. .......................................................................... 6-6

Figure 6.1.6. Short-term (2000–2008) trends (% yr-1) in 10th percentile sulfate ion mass 

concentrations. ............................................................................................................................. 6-9

Figure 6.1.7. Short-term (2000–2008) trends (% yr-1) in average winter sulfate ion mass 

concentrations. ........................................................................................................................... 6-10

Figure 6.1.8. Average spring sulfate ion mass concentrations (μg m-3) for Martha’s Vineyard, 

Massachusetts (MAVI1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, 

μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid 

line. The intercept corresponds to the initial year of data.......................................................... 6-10
xxix

IMPROVE REPORT V

Figure 6.1.9. Short-term (2000–2008) trends (% yr-1) in average spring sulfate ion mass 

concentrations. ........................................................................................................................... 6-13

Figure 6.1.10. Average spring sulfate ion mass concentrations (μg m-3) for Hawaii Volcanoes 

(HAVO1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-14

Figure 6.2.1. Short-term (2000–2008) trends (% yr-1) in 10th percentile nitrate ion mass 

concentrations. ........................................................................................................................... 6-15

Figure 6.2.2. Average winter nitrate ion mass concentrations (μg m-3) for Trinity, California 

(TRIN1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-15

Figure 6.2.3. Short-term (2000–2008) trends (% yr-1) in average fall nitrate ion mass 

concentrations. ........................................................................................................................... 6-16

Figure 6.2.4. Short-term (2000–2008) trends (% yr-1) in 50th percentile nitrate ion mass 

concentrations. ........................................................................................................................... 6-17

Figure 6.2.5. Short-term (2000–2008) trends (% yr-1) in average spring nitrate ion mass 

concentrations. ........................................................................................................................... 6-17

Figure 6.2.6. Average winter nitrate ion mass concentrations (μg m-3) for Jarbidge NV 

(JARB1). Regression results, including Theil slope (m, μg m-3yr

-1

), intercept (b, μg m-3), 

significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-18

Figure 6.3.1. Long-term (1989–2008) trends (% yr-1) in 10th percentile total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations................................................. 6-19

Figure 6.3.2. 10th percentile total carbon (TC = organic carbon + light absorbing carbon) mass 

concentrations (μg m-3) for Three Sisters, Oregon (THSI1). Regression results, including Theil 

slope (m, μg m-3yr-1), intercept (b, μg m-3), significance (s), and trend (t, % yr-1) are included. 

The trend line is plotted as a solid line. The intercept corresponds to the initial year of data... 6-19

Figure 6.3.3. Long-term (1989–2008) trends (% yr-1) in average winter total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations................................................. 6-20

Figure 6.3.4. Average winter total carbon (TC = organic carbon + light absorbing carbon) 

mass concentrations (μg m-3) for Mount Rainier, Washington (MORA1). Regression results, 

including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), significance (s), and trend (t, % yr-1) 

are included. The trend line is plotted as a solid line. The intercept corresponds to the initial year 

of data......................................................................................................................................... 6-20

Figure 6.3.5. Long-term (1989–2008) trends (% yr-1) in 90th percentile total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations................................................. 6-21

Figure 6.3.6. 90th percentile total carbon (TC = organic carbon + light absorbing carbon) mass 

concentrations (μg m-3) for Bridger, Wyoming (BRID1). Regression results, including Theil 

slope (m, μg m-3yr-1), intercept (b, μg m-3), significance (s), and trend (t, % yr-1) are included. 

The trend line is plotted as a solid line. The intercept corresponds to the initial year of data... 6-21
xxx

IMPROVE REPORT V

Figure 6.3.7. Long-term (1989–2008) trends (% yr-1) in average summer total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations................................................. 6-22

Figure 6.3.8. Average summer total carbon (TC = organic carbon + light absorbing carbon) 

mass concentrations (μg m-3) for Bridger, Wyoming (BRID1). Regression results, including 

Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), significance (s), and trend (t, % yr-1) are 

included. The trend line is plotted as a solid line. The intercept corresponds to the initial year of 

data............................................................................................................................................. 6-22

Figure 6.3.9. Short-term (2000–2008) trends (% yr-1) in 10th percentile total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations................................................. 6-23

Figure 6.3.10. 10th percentile total carbon (TC = organic carbon + light absorbing carbon) 

mass concentrations (μg m-3) for Three Sisters, Oregon (THSI1). Regression results, including 

Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), significance (p), and trend (t, % yr-1) are 

included. The trend line is plotted as a solid line. The intercept corresponds to the initial year of 

data............................................................................................................................................. 6-24

Figure 6.3.11. Short-term (2000–2008) trends (% yr-1) in average winter total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations................................................. 6-24

Figure 6.3.12. Short-term (2000–2008) trends (% yr-1) in 50th percentile total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations................................................. 6-25

Figure 6.3.13. 50th percentile total carbon (TC = organic carbon + light absorbing carbon) 

mass concentrations (μg m-3) for Hawaii Volcanoes (HAVO1). Regression results, including 

Theil slope (m, μg m-3yr

-1

), intercept (b, μg m-3), significance (p), and trend (t, % yr-1) are 

included. The trend line is plotted as a solid line. The intercept corresponds to the initial year of 

data............................................................................................................................................. 6-25

Figure 6.3.14. Short-term (2000–2008) trends (% yr-1) in average summer total carbon (TC = 

organic carbon + light absorbing carbon) mass concentrations................................................. 6-26

Figure 6.3.15. Average summer total carbon (TC = organic carbon + light absorbing carbon) 

mass concentrations (μg m-3) for Gates of the Mountains, Montana (GAMO1). Regression 

results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), significance (p), and trend (t, 

% yr-1) are included. The trend line is plotted as a solid line. The intercept corresponds to the 

initial year of data. ..................................................................................................................... 6-26

Figure 6.4.1. Long-term (1989–2008) trends (% yr-1) in 10th percentile fine soil mass 

concentrations. ........................................................................................................................... 6-28

Figure 6.4.2. 10th percentile fine soil mass concentrations (μg m-3) for Denali, Alaska 

(DENA1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (s), and trend (t, % yr-1) are included. The intercept corresponds to the initial year of 

data............................................................................................................................................. 6-28

Figure 6.4.3. Long-term (1989–2008) trends (% yr-1) in average winter fine soil mass 

concentrations. ........................................................................................................................... 6-29

Figure 6.4.4. Average summer fine soil mass concentrations (μg m-3) for Virgin Islands 

(VIIS1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 
xxxi

IMPROVE REPORT V

significance (s), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-29

Figure 6.4.5. Long-term (1989–2008) trends (% yr-1) in 90th percentile fine soil mass 

concentrations. ........................................................................................................................... 6-30

Figure 6.4.6. 90th percentile fine soil mass concentrations (μg m-3) for Columbia River Gorge, 

Washington (CORI1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg 

m

-3

), significance (s), and trend (t, % yr-1) are included. The intercept corresponds to the initial 

year of data................................................................................................................................. 6-30

Figure 6.4.7. 90th percentile fine soil mass concentrations (μg m-3) for Denali, Alaska 

(DENA1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (s), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-31

Figure 6.4.8. Long-term (1989–2008) trends (% yr-1) in average spring fine soil mass 

concentrations. ........................................................................................................................... 6-31

Figure 6.4.9. Average spring fine soil mass concentrations (μg m-3) for Death Valley, 

California (DEVA1). Regression results, including Theil slope (m, μg m-3yr

-1

), intercept (b, μg 

m

-3

), significance (s), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. 

The intercept corresponds to the initial year of data.................................................................. 6-32

Figure 6.4.10. Short-term (2000–2008) trends (% yr-1) in 10th percentile fine soil mass 

concentrations. ........................................................................................................................... 6-33

Figure 6.4.11. Short-term (2000–2008) trends (% yr-1) in 50th percentile fine soil mass 

concentrations. ........................................................................................................................... 6-33

Figure 6.4.12. Short-term (2000–2008) trends (% yr-1) in average winter fine soil mass 

concentrations. ........................................................................................................................... 6-34

Figure 6.4.13. Average winter fine soil mass concentrations (μg m-3) for Big Bend, Texas 

(BIBE1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-34

Figure 6.4.14. Short-term (2000–2008) trends (% yr-1) in 90th percentile fine soil mass 

concentrations. ........................................................................................................................... 6-35

Figure 6.4.15. Short-term (2000–2008) trends (% yr-1) in average fall fine soil mass 

concentrations. ........................................................................................................................... 6-35

Figure 6.4.16. Average fall fine soil mass concentrations (μg m-3) for Zion Canyon, Utah 

(ZICA1). Regression results, including Theil slope (m, μg m-3yr

-1

), intercept (b, μg m-3), 

significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-36

Figure 6.4.17. Fall fine soil mass concentrations (μg m-3) for Mesa Verde, Colorado 

(MEVE1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-36
xxxii

IMPROVE REPORT V

Figure 6.5.1. Long-term (1989–2008) trends (% yr-1) in 10th percentile PM2.5 gravimetric fine 

mass (FM) concentrations.......................................................................................................... 6-37

Figure 6.5.2. 10th percentile PM2.5 gravimetric fine mass (FM) concentrations (μg m-3) for 

Craters of the Moon, Idaho (CRMO1). Regression results, including Theil slope (m, μg m-3yr-1), 

intercept (b, μg m-3), significance (s), and trend (t, % yr-1) are included. The trend line is plotted 

as a solid line. The intercept corresponds to the initial year of data.......................................... 6-38

Figure 6.5.3. Long-term (1989–2008) trends (% yr-1) in average winter PM2.5 gravimetric fine 

mass (FM) concentrations.......................................................................................................... 6-38

Figure 6.5.4. Long-term (1989–2008) trends (% yr-1) in 90th percentile PM2.5 gravimetric fine 

mass (FM) concentrations.......................................................................................................... 6-39

Figure 6.5.5. 90th percentile PM2.5 gravimetric fine mass (FM) concentrations (μg m-3) for 

Sawtooth, Idaho (SAWT1). Regression results, including Theil slope (m, μg m-3yr-1), intercept 

(b, μg m-3), significance (s), and trend (t, % yr-1) are included. The trend line is plotted as a solid 

line. The intercept corresponds to the initial year of data.......................................................... 6-40

Figure 6.5.6. Long-term (1989–2008) trends (% yr-1) in average summer PM2.5 gravimetric 

fine mass (FM) concentrations................................................................................................... 6-40

Figure 6.5.7. Short-term (2000–2008) trends (% yr-1) in 90th percentile PM2.5 gravimetric fine 

mass (FM) concentrations.......................................................................................................... 6-41

Figure 6.5.8. 90th percentile PM2.5 gravimetric fine mass (FM) concentrations (μg m-3) for 

Hawaii Volcanoes (HAVO1). Regression results, including Theil slope (m, μg m-3yr

-1

), intercept 

(b, μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid 

line. The intercept corresponds to the initial year of data.......................................................... 6-41

Figure 6.5.9. Short-term (2000–2008) trends (% yr-1) in average winter PM2.5 gravimetric fine 

mass (FM) concentrations.......................................................................................................... 6-42

Figure 6.5.10. Average winter PM2.5 gravimetric fine mass (FM) concentrations (μg m-3) for 

Starkey, Oregon (STAR1). Regression results, including Theil slope (m, μg m-3yr-1), intercept 

(b, μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid 

line. The intercept corresponds to the initial year of data.......................................................... 6-42

Figure 6.5.11. Average winter PM2.5 gravimetric fine mass (FM) concentrations (μg m-3) for 

Trapper Creek, Alaska (TRCR1). Regression results, including Theil slope (m, μg m-3yr-1), 

intercept (b, μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted 

as a solid line. The intercept corresponds to the initial year of data.......................................... 6-43

Figure 6.5.12. Short-term (2000–2008) trends (% yr-1) in average fall PM2.5 gravimetric fine 

mass (FM) concentrations.......................................................................................................... 6-44

Figure 6.5.13. Average fall PM2.5 gravimetric fine mass (FM) concentrations (μg m-3) for Zion 

Canyon, Utah (ZICA1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, 

μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid 

line. The intercept corresponds to the initial year of data.......................................................... 6-44

Figure 6.6.1. Long-term (1989–2008) trends (% yr-1) in 10th percentile coarse mass (CM = 

PM10 - PM2.5) concentrations. .................................................................................................... 6-45
xxxiii

IMPROVE REPORT V

Figure 6.6.2. 10th percentile coarse mass (CM = PM10 - PM2.5) concentrations (μg m-3) for 

Mount Zirkel, Colorado (MOZI1). Regression results, including Theil slope (m, μg m-3yr-1), 

intercept (b, μg m-3), significance (s), and trend (t, % yr-1) are included. The trend line is plotted 

as a solid line. The intercept corresponds to the initial year of data.......................................... 6-45

Figure 6.6.3. Long-term (1989–2008) trends (% yr-1) in average winter coarse mass (CM = 

PM10 - PM2.5) concentrations. .................................................................................................... 6-46

Figure 6.6.4. Average winter coarse mass (CM = PM10 - PM2.5) concentrations (μg m-3) for 

Snoqualmie Pass, Washington (SNPA1). Regression results, including Theil slope (m, μg m-3yr1

), intercept (b, μg m-3), significance (s), and trend (t, % yr-1) are included. The trend line is 

plotted as a solid line. The intercept corresponds to the initial year of data.............................. 6-46

Figure 6.6.5. Long-term (1989–2008) trends (% yr-1) in 90th percentile coarse mass (CM = 

PM10 - PM2.5) concentrations. .................................................................................................... 6-47

Figure 6.6.6. 90th percentile coarse mass (CM = PM10 - PM2.5) concentrations (μg m-3) for 

Yosemite, California (YOSE1). Regression results, including Theil slope (m, μg m-3yr

-1

), 

intercept (b, μg m-3), significance (s), and trend (t, % yr-1) are included. The trend line is plotted 

as a solid line. The intercept corresponds to the initial year of data.......................................... 6-47

Figure 6.6.7. 90th percentile coarse mass (CM = PM10 - PM2.5) concentrations (μg m-3) for 

Snoqualmie Pass, Washington (SNPA1). Regression results, including Theil slope (m, μg m-3yr

-

1

), intercept (b, μg m-3), significance (s), and trend (t, % yr-1) are included. The intercept 

corresponds to the initial year of data. ....................................................................................... 6-48

Figure 6.6.8. Long-term (1989–2008) trends (% yr-1) in average summer coarse mass (CM = 

PM10 - PM2.5) concentrations. .................................................................................................... 6-48

Figure 6.6.9. Short-term (2000–2008) trends (% yr-1) in 90th percentile coarse mass (CM = 

PM10 - PM2.5) concentrations. .................................................................................................... 6-49

Figure 6.6.10. 90th percentile coarse mass (CM = PM10 - PM2.5) concentrations (μg m-3) for 

Monture, Montana (MONT1). Regression results, including Theil slope (m, μg m-3yr-1), 

intercept (b, μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted 

as a solid line. The intercept corresponds to the initial year of data.......................................... 6-49

Figure 6.6.11. Short-term (2000–2008) trends (% yr-1) in average winter coarse mass (CM = 

PM10 - PM2.5) concentrations. .................................................................................................... 6-50

Figure 6.6.12. Average winter coarse mass (CM = PM10 - PM2.5) concentrations (μg m-3) for 

Hoover, California (HOOV1). Regression results, including Theil slope (m, μg m-3yr-1), 

intercept (b, μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted 

as a solid line. The intercept corresponds to the initial year of data.......................................... 6-50

Figure 6.6.13. Short-term (2000–2008) trends (% yr-1) in 50th percentile coarse mass (CM = 

PM10 - PM2.5) concentrations. .................................................................................................... 6-51

Figure 6.6.14. Short-term (2000–2008) trends (% yr-1) in average summer coarse mass (CM = 

PM10 - PM2.5) concentrations ..................................................................................................... 6-51

Figure 6.6.15. Average summer coarse mass (CM = PM10 - PM2.5) concentrations (μg m-3) for 

Indian Gardens, Arizona (INGA1). Regression results, including Theil slope (m, μg m-3yr-1), 
xxxiv

IMPROVE REPORT V

intercept (b, μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted 

as a solid line. The intercept corresponds to the initial year of data.......................................... 6-52

Figure 6.6.16. Average summer coarse mass (CM = PM10 - PM2.5) concentrations (μg m-3) for 

Olympic, Washington (OLYM1). Regression results, including Theil slope (m, μg m-3yr-1), 

intercept (b, μg m-3), significance (p), and trend (t, % yr-1) are included. The trend line is plotted 

as a solid line. The intercept corresponds to the initial year of data.......................................... 6-52

Figure 6.7.1. Long-term (1989–2008) trends (% yr-1) in 10th percentile PM10 gravimetric mass 

concentrations. ........................................................................................................................... 6-53

Figure 6.7.2. Long-term (1989–2008) trends (% yr-1) in average winter PM10 gravimetric mass 

concentrations. ........................................................................................................................... 6-54

Figure 6.7.3. Average winter PM10 gravimetric mass concentrations (μg m-3) for Snoqualmie 

Pass, Washington (SNPA1). Regression results, including Theil slope (m, μg m-3yr-1), intercept 

(b, μg m-3), significance (s), and trend (t, % yr-1) are included. The trend line is plotted as a solid 

line. The intercept corresponds to the initial year of data.......................................................... 6-54

Figure 6.7.4. Long-term (1989–2008) trends (% yr-1) in 90th percentile PM10 gravimetric mass 

concentrations. ........................................................................................................................... 6-55

Figure 6.7.5. Long-term (1989–2008) trends (% yr-1) in average summer PM10 gravimetric 

mass concentrations. .................................................................................................................. 6-55

Figure 6.7.6. Short-term (2000–2008) trends (% yr-1) in 10th percentile PM10 gravimetric mass 

concentrations. ........................................................................................................................... 6-56

Figure 6.7.7. Short-term (2000–2008) trends (% yr-1) in average winter PM10 gravimetric mass 

concentrations. ........................................................................................................................... 6-57

Figure 6.7.8. Average winter PM10 gravimetric mass concentrations (μg m-3) for Bondville, 

Illinois (BOND1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m3

), significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-57

Figure 6.7.9. Short-term (2000–2008) trends (% yr-1) in 90th percentile PM10 gravimetric mass 

concentrations. ........................................................................................................................... 6-58

Figure 6.7.10. Short-term (2000–2008) trends (% yr-1) in average fall PM10 gravimetric mass 

concentrations. ........................................................................................................................... 6-58

Figure 6.7.11. Average fall PM10 gravimetric mass concentrations (μg m-3) for Gila, New 

Mexico (GICL1). Regression results, including Theil slope (m, μg m-3yr-1), intercept (b, μg m-3), 

significance (p), and trend (t, % yr-1) are included. The trend line is plotted as a solid line. The 

intercept corresponds to the initial year of data. ........................................................................ 6-59

Figure 6.7.12. Split-image of visibility conditions in Linville Gorge, NC (LIVO) for 50th

percentile speciated aerosol levels in 2000 (left-side) and 2008 (right-side). Images were 

generated using WinHaze 2.9.9. ................................................................................................ 6-60

Figure 7.1. Schematic showing urban sources of aerosol concentrations and their impact on 

surrounding rural concentrations. An arbitrary concentration scale is on the y-axis and distance is 
xxxv

IMPROVE REPORT V

on the x-axis. The concentrations levels depicted in orange represent levels above a rural 

background, depicted as blue.......................................................................................................7-2

Figure 7.2.1. Interpolated annual mean ammonium sulfate (AS) concentrations (μg m-3) for 

the rural IMPROVE network for 2005–2008. IMPROVE site locations are shown as black 

circles. .......................................................................................................................................... 7-5

Figure 7.2.2. Interpolated annual mean ammonium sulfate (AS) concentrations (μg m-3) for 

the rural IMPROVE and urban CSN networks for 2005–2008. IMPROVE site locations are 

shown as black circles, CSN sites are shown as black triangles, and urban IMPROVE sites are 

shown as magenta diamonds........................................................................................................ 7-5

Figure 7.2.3. Interpolated ratios of urban (CSN) to rural (IMPROVE) annual mean ammonium 

sulfate (AS) concentrations for 2005–2008. IMPROVE sites are shown as circles, CSN sites with 

an IMPROVE monitor within 150 km are depicted as squares, and CSN sites not used in the 

analyses are shown as triangles.................................................................................................... 7-6

Figure 7.2.4. Interpolated differences (μg m-3) in urban (CSN) to rural (IMPROVE) annual 

mean ammonium sulfate (AS) concentrations for 2005–2008. IMPROVE sites are shown as 

circles, CSN sites with an IMPROVE monitor within 150 km are depicted as squares, and CSN 

sites not used in the analyses are shown as triangles. .................................................................. 7-7

Figure 7.3.1. Interpolated annual mean ammonium nitrate (AN) concentrations (μg m-3) for 

the rural IMPROVE network for 2005–2008. IMPROVE site locations are shown as black 

circles. .......................................................................................................................................... 7-8

Figure 7.3.2. Interpolated annual mean ammonium nitrate (AN) concentrations (μg m-3) for 

the rural IMPROVE and urban CSN networks for 2005–2008. IMPROVE site locations are 

shown as black circles, CSN sites are shown as black triangles, and urban IMPROVE sites are 

shown as magenta diamonds........................................................................................................ 7-8

Figure 7.3.3. Interpolated ratios of urban (CSN) to rural (IMPROVE) annual mean ammonium 

nitrate (AN) concentrations for 2005–2008. IMPROVE sites are shown as circles, CSN sites with 

an IMPROVE monitor within 150 km are depicted as squares, and CSN sites not used in the 

analyses are shown as triangles.................................................................................................... 7-9

Figure 7.3.4. Interpolated differences (μg m-3) in urban (CSN) to rural (IMPROVE) annual 

mean ammonium nitrate (AN) concentrations for 2005–2008. IMPROVE sites are shown as 

circles, CSN sites with an IMPROVE monitor within 150 km are depicted as squares, and CSN 

sites not used in the analyses are shown as triangles. ................................................................ 7-10

Figure 7.4.1. Interpolated annual mean particulate organic matter (POM) concentrations (μg 

m

-3

) for the rural IMPROVE network for 2005–2008. IMPROVE site locations are shown as 

black circles. .............................................................................................................................. 7-11

Figure 7.4.2. Interpolated annual mean particulate organic matter (POM) concentrations (μg 

m

-3

) for the rural IMPROVE and urban CSN networks for 2005–2008. IMPROVE site locations 

are shown as black circles, CSN sites are shown as black triangles, and urban IMPROVE sites 

are shown as magenta diamonds................................................................................................ 7-12

Figure 7.4.3. Interpolated ratios of urban (CSN) to rural (IMPROVE) annual mean particulate 

organic matter (POM) concentrations for 2005–2008. IMPROVE sites are shown as circles, CSN 
xxxvi

IMPROVE REPORT V

sites with an IMPROVE monitor within 150 km are depicted as squares, and CSN sites not used 

in the analyses are shown as triangles........................................................................................ 7-13

Figure 7.4.4. Interpolated differences (μg m-3) in urban (CSN) to rural (IMPROVE) annual 

mean particulate organic matter (POM) concentrations for 2005–2008. IMPROVE sites are 

shown as circles, CSN sites with an IMPROVE monitor within 150 km are depicted as squares, 

and CSN sites not used in the analyses are shown as triangles. ................................................ 7-14

Figure 7.5.1. Interpolated annual mean light absorbing carbon (LAC) concentrations (μg m-3) 

for the rural IMPROVE network for 2005–2008. IMPROVE site locations are shown as black 

circles. ........................................................................................................................................ 7-15

Figure 7.5.2. Interpolated annual mean light absorbing carbon (LAC) concentrations (μg m-3) 

for the rural IMPROVE and urban CSN networks for 2005–2008. IMPROVE site locations are 

shown as black circles, CSN sites are shown as black triangles, and urban IMPROVE sites are 

shown as magenta diamonds...................................................................................................... 7-15

Figure 7.5.3. Interpolated ratios of urban (CSN) to rural (IMPROVE) annual mean light 

absorbing carbon (LAC) concentrations for 2005–2008. IMPROVE sites are shown as circles, 

CSN sites with an IMPROVE monitor within 150 km are depicted as squares, and CSN sites not 

used in the analyses are shown as triangles. .............................................................................. 7-16

Figure 7.5.4. Interpolated differences (μg m-3) in urban (CSN) to rural (IMPROVE) annual 

mean light absorbing carbon (LAC) concentrations for 2005–2008. IMPROVE sites are shown 

as circles, CSN sites with an IMPROVE monitor within 150 km are depicted as squares, and 

CSN sites not used in the analyses are shown as triangles. ....................................................... 7-17

Figure 7.6.1. Interpolated annual mean PM2.5 gravimetric fine mass (FM) concentrations (μg 

m

-3

) for the rural IMPROVE network for 2005–2008. IMPROVE site locations are shown as 

black circles. .............................................................................................................................. 7-18

Figure 7.6.2. Interpolated annual mean PM2.5 gravimetric fine mass (FM) concentrations (μg 

m

-3

) for the rural IMPROVE and urban CSN networks for 2005–2008. IMPROVE site locations 

are shown as black circles, CSN sites are shown as black triangles, and urban IMPROVE sites 

are shown as magenta diamonds................................................................................................ 7-18

Figure 7.6.3. Interpolated ratios of urban (CSN) to rural (IMPROVE) annual mean PM2.5

gravimetric fine mass (FM) concentrations for 2005–2008. IMPROVE sites are shown as circles, 

CSN sites with an IMPROVE monitor within 150 km are depicted as squares, and CSN sites not 

used in the analyses are shown as triangles. .............................................................................. 7-19

Figure 7.6.4. Interpolated differences (μg m-3) in urban (CSN) to rural (IMPROVE) annual 

mean PM2.5 gravimetric fine mass (FM) concentrations for 2005–2008. IMPROVE sites are 

shown as circles, CSN sites with an IMPROVE monitor within 150 km are depicted as squares, 

and CSN sites not used in the analyses are shown as triangles. ................................................ 7-20

Figure 7.7.1(a). Comparisons of 2005–2008 annual mean IMPROVE rural concentration 

(interpolated) on the x-axis and CSN urban concentration (data) on the y-axis for ammonium 

sulfate (AS, yellow), ammonium nitrate (AN, red), particulate organic matter (POM, green), and 

light absorbing carbon (LAC, black). Concentrations are in μg m-3.......................................... 7-21

Figure 7.7.1(b). Same as part (a) but with a logarithmic scale.............................................. 7-21
xxxvii

IMPROVE REPORT V

Figure 8.1. Location of the twelve urban sites with collocated IMPROVE and CSN carbon 

measurements and the time period the samplers were operating.................................................8-6

Figure 8.2. Comparison of CSN TC and IMPROVE TC concentrations from collocated 

monitors for 2005–2006 data. The data are color coded based on the CSN sampler. The 

regression line is for the Met One data. ....................................................................................... 8-7

Figure 8.3. Comparison of CSN EC and IMPROVE EC concentrations from collocated 

monitors for 2005–2006 data. The data are color coded based on the CSN sampler. The 

regression line is for the Met One data. ....................................................................................... 8-8

Figure 8.4. The CSN and IMPROVE TC, OC, and EC concentrations for all collocated 

IMPROVE and CSN Met One samplers that collected data in 2005 and 2006. The lighter data 

points are for the reported CSN carbon concentrations and the darker data points are for the 

adjusted CSN carbon concentrations. ........................................................................................ 8-12

Figure 8.5. Stacked bar charts showing average concentrations of each species for all and 

each season for IMPROVE, CSN suburban, and CSN center city. ........................................... 8-16

Figure 8.6. Temporal plot of PM2.5 − PM2.5avg and the percent difference between 

reconstructed and gravimetric mass for Brigantine National Wildlife Refuge. The red line is a 

sinusoidal curve fit to the percent difference between reconstructed and gravimetric mass..... 8-18

Figure 8.7. Average percent seasonal variability (b2) and percent difference (b1), as 

represented by equation 8.13, between reconstructed and gravimetric mass for the IMPROVE 

and CSN monitoring networks. Green represents a positive value while red represents a negative 

bias. ............................................................................................................................................ 8-19

Figure 8.8. Average fractional increase in sulfate and nitrate mass, a1, due to retained water 

for the IMPROVE and CSN monitoring networks. ................................................................... 8-25

Figure 8.9. Average fraction of nitrate volatilized from a Teflon filter, (1 – a2/a1), for the 

IMPROVE and CSN monitoring networks................................................................................ 8-25

Figure 8.10. Average Roc factor, a3, for the IMPROVE and CSN monitoring networks.... 8-25

Figure 8.11. The estimated average difference between gravimetric and assumed forms of the 

various aerosol species contributing to PM 2.5 for IMPROVE. The differences are estimated as 

1.375*SO4(a1 – 1), 1.29*NO3(a2 – 1), OC*(a3 – 1.8), and Other*(a4 – 1) for sulfates, nitrates, 

organics, and Other, respectively............................................................................................... 8-26

Figure 8.12. The estimated average difference between gravimetric and assumed forms of the 

various aerosol species contributing to PM 2.5 for CSN center city. The differences are estimated 

as 1.375*SO4(a1 – 1), 1.29*NO3(a2 – 1), OC*(a3 – 1.8), and Other*(a4 – 1) for sulfates, nitrates, 

organics, and Other, respectively............................................................................................... 8-26

Figure 8.13. The estimated average difference between gravimetric and assumed forms of the 

various aerosol species contributing to PM 2.5 for CSN suburban. The differences are estimated 

as 1.375*SO4(a1 – 1), 1.29*NO3(a2 – 1), OC*(a3 – 1.8), and Other*(a4 – 1) for sulfates, nitrates, 

organics, and Other, respectively............................................................................................... 8-26

Figure 8.14. Average difference between gravimetric and estimated true PM2.5 mass 

concentration for the IMPROVE and CSN datasets (see equation 8.16). ................................. 8-28
xxxviii

IMPROVE REPORT V

Figure 8.15. Average difference between reconstructed and estimated true PM2.5

concentrations for the IMPROVE and CSN datasets (see equation 8.17)................................. 8-29

Figure 8.16. Seasonal and spatial variability in difference between gravimetric and true mass 

concentration (PM2.5 – TPM2.5) for the CSN monitoring network. Green color refers to positive 

and red to negative numbers. ..................................................................................................... 8-30

Figure 8.17. Seasonal and spatial variability in difference between gravimetric and true mass 

concentration (PM2.5 – TPM2.5) for the IMPROVE monitoring network. Green color refers to 

positive and red to negative numbers......................................................................................... 8-31

Figure 8.18. Seasonal and spatial variability in difference between true and reconstructed 

mass concentration (TPM2.5 – RPM2.5) for the CSN monitoring network. Green color refers to 

positive and red to negative numbers......................................................................................... 8-32

Figure 8.19. Seasonal and spatial variability in difference between true and reconstructed 

mass concentration (TPM2.5 – RPM2.5) for the IMPROVE monitoring network. Green color 

refers to positive and red to negative numbers. ......................................................................... 8-33

Figure 9.2.1. Depiction of the conceptual uniform rate of progress (URG) glide path (EPA, 

1999). ...........................................................................................................................................9-3

Figure 9.2.2. Depiction of realistic uniform rate of progress (URG) glide path (Husar, 2003).

...................................................................................................................................................... 9-3

Figure 9.3.1. Fraction of dv uniform rate of progress (URP) from the baseline (2000–2004) to 

period 1 (2005–2009) for the 20% worst visibility days at 107 of the 110 IMPROVE regional 

haze tracking sites. Brown circles indicate degradation in the worst 20% visibility days, while 

blue circles represent improvement in worst 20% visibility days. The two darkest shades of blue 

indicate progress that is at or better than the 2009 point value on the slope of the nominal URP 

line................................................................................................................................................ 9-7

Figure 9.3.2. Absolute change in dv from the baseline (2000–2004) to period 1 (2005–2009) 

for the 20% worst visibility days at 107 of the 110 IMPROVE regional haze tracking sites. 

Brown circles indicate degradation in the worst 20% visibility days, while blue circles represent 

improvement in worst 20% visibility days. ................................................................................. 9-8

Figure 9.3.3. Absolute change in dv from the baseline (2000–2004) to period 1 (2005–2009) 

for the 20% best visibility days at 107 of the 110 IMPROVE regional haze tracking sites. Brown 

circles indicate degradation in the best 20% visibility days, while blue circles represent 

improvement in best 20% visibility days..................................................................................... 9-9

Figure 9.3.4. Absolute change in annual mean dv from the baseline (2000–2004) to period 1 

(2005–2009) at 107 of the 110 IMPROVE regional haze tracking sites. Brown circles indicate 

degradation in annual mean dv, while blue circles represent improvement in annual mean dv.. 9-9

Figure 9.3.5. Fraction of hypothetical ammonium sulfate uniform rate of progress (URP) for 

the 20% worst visibility days at 107 of the 110 IMPROVE regional haze tracking sites from the 

baseline (2000–2004) to period 1 (2005–2009). Brown circles indicate degradation in the worst 

20% visibility days due to ammonium sulfate extinction, while blue circles represent 

improvement in worst 20% visibility days due to ammonium sulfate extinction. Only the two 

darkest blue colored circles indicate progress that is at or better than the hypothetical ammonium 

sulfate extinction 2009 point value on the slope of the nominal URP line................................ 9-11
xxxix

IMPROVE REPORT V

Figure 9.3.6. Fraction of hypothetical ammonium nitrate uniform rate of progress (URP) for 

the 20% worst visibility days at 107 of the 110 IMPROVE regional haze tracking sites from the 

baseline (2000–2004) to period 1 (2005–2009). Brown circles indicate degradation in the worst 

20% visibility days due to ammonium nitrate extinction, while blue circles represent 

improvement in worst 20% visibility days due to ammonium nitrate extinction. Only the two 

darkest blue colored circles indicate progress that is at or better than the hypothetical ammonium 

sulfate extinction 2009 point value on the slope of the nominal URP line................................ 9-12

Figure 9.3.7. Change in annual mean ammonium nitrate extinction (bext_AN, Mm-1) at 107 of 

the 110 IMPROVE regional haze tracking sites from the baseline (2000-2004) to period 1 (2005-

2009). Brown circles indicate an increase of the annual mean bext_AN, while blue circles represent 

decreases in annual mean bext_AN. .............................................................................................. 9-13

Figure 9.3.8. Change in annual mean ammonium sulfate extinction (bext_AS, Mm-1) at 107 of 

the 110 IMPROVE regional haze tracking sites from the baseline (2000–2004) to period 1 

(2005–2009). Brown circles indicate an increase of the annual mean bext_AS, while blue circles 

represent decreases in annual mean bext_AS. ............................................................................... 9-13

Figure 9.4.1.1a. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the worst 20% visibility days at 

Boundary Waters Canoe Area Wilderness, MN. Values of bext for other species, including 

elemental carbon (EC), soil, coarse mass and sea salt are listed in the table below the graph (data 

and graphs obtained at http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx)............. 9-15

Figure 9.4.1.1b. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the best 20% visibility days at Boundary 

Waters Canoe Area Wilderness, MN. Values of bext for other species, including elemental carbon 

(EC), soil, coarse mass and sea salt are listed in the table below the graph (data and graphs 

obtained at http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx). .............................. 9-15

Figure 9.4.1.2a. Daily light extinction coefficients (bext, Mm-1) for ammonium sulfate 

(ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext) and sea salt 

(seasalt_bext) for 2001 Boundary Waters Canoe Area (BOWA1). Worst 20% days are marked 

with a “W” above the bar for that day, and similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-16

Figure 9.4.1.2b. Daily light extinction coefficients (bext, Mm-1) for ammonium sulfate 

(ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext) and sea salt 

(seasalt_bext) for 2005 Boundary Waters Canoe Area (BOWA1). Worst 20% days are marked 

with a “W” above the bar for that day, and similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-16

Figure 9.4.2.1a. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the worst 20% visibility days at Great 

Smoky Mountains NP, TN and Joyce Kilmer-Slickrock WA, NC. Values of bext for other 
xl

IMPROVE REPORT V

species, including elemental carbon (EC), soil, coarse mass and sea salt are listed in the table 

below the graph (data and graphs obtained at 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).................................................. 9-18

Figure 9.4.2.1b. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the best 20% visibility days at Great 

Smoky Mountains NP, TN and Joyce Kilmer-Slickrock WA, NC. Values of bext for other 

species, including elemental carbon (EC), soil, coarse mass and sea salt are listed in the table 

below the graph (data and graphs obtained at 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).................................................. 9-18

Figure 9.4.2.2a. Daily light extinction coefficients (bext, Mm-1) for ammonium sulfate 

(ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext) and sea salt 

(seasalt_bext) for 2001 Great Smoky Mountains NP, TN (GRSM1) and Joyce Kilmer-Slickrock 

WA, NC. Worst 20% days are marked with a “W” above the bar for that day, and similarly, best 

20% days are marked with a “B” (from http://views.cira.colostate.edu/web/Composition/).... 9-19

Figure 9.4.2.2b. Daily light extinction coefficients (bext, Mm-1) for ammonium sulfate 

(ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext) and sea salt 

(seasalt_bext) for 2008 at Great Smoky Mountains NP, TN (GRSM1) and Joyce KilmerSlickrock WA, NC. Worst 20% days are marked with a “W” above the bar for that day, and 

similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-19

Figure 9.4.3.1a. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the worst 20% visibility days at Mesa 

Verde NP, CO. Values of bext for other species, including elemental carbon (EC), soil, coarse 

mass, and sea salt are listed in the table below the graph (data and graphs obtained at 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).................................................. 9-21

Figure 9.4.3.1b. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the best 20% visibility days at Mesa 

Verde NP, CO. Values of bext for other species, including elemental carbon (EC), soil, coarse 

mass, and sea salt are listed in the table below the graph. (Data and graphs obtained at 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).................................................. 9-21

Figure 9.4.3.2a. Daily light extinction coefficients (bext, Mm-1) for ammonium sulfate 

(ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext), and sea salt 

(seasalt_bext) for 2004 Mesa Verde NP, CO. Worst 20% days are marked with a “W” above the 

bar for that day, and similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-24

Figure 9.4.3.3b. Daily light extinction coefficients (bext, Mm-1) for ammonium sulfate 

(ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 
xli

IMPROVE REPORT V

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext), and sea salt 

(seasalt_bext) for 2008 Mesa Verde NP, CO. Worst 20% days are marked with a “W” above the 

bar for that day, and similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-24

Figure 9.4.4.1a. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the worst 20% visibility days at Hell’s 

Canyon WA, OR/ID. Values of bext for other species, including elemental carbon (EC), soil, 

coarse mass, and sea salt are listed in the table below the graph (data and graphs obtained at 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).................................................. 9-26

Figure 9.4.4.1b. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the best 20% visibility days at Hell’s 

Canyon WA, OR/ID. Values of bext for other species, including elemental carbon (EC), soil, 

coarse mass, and sea salt are listed in the table below the graph (data and graphs obtained at 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).................................................. 9-26

Figure 9.4.4.2a. Daily light extinction coefficients (bext, Mm-1) for ammonium sulfate 

(ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext), and sea salt 

(seasalt_bext) for 2004 Hells Canyon, ID (HECA1). Worst 20% days are marked with a “W” 

above the bar for that day, and similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-27

Figure 9.4.4.2b. Daily light extinction coefficients (bext, Mm-1) for ammonium sulfate 

(ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext), and sea salt 

(seasalt_bext) for 2006 Hells Canyon, ID (HECA1). Worst 20% days are marked with a “W” 

above the bar for that day, and similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-27

Figure 9.4.5.2a. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the worst 20% visibility days at Agua 

Tibia Wilderness, CA. Values of bext for other species, including elemental carbon (EC), soil, 

coarse mass, and sea salt are listed in the table below the graph (data and graphs obtained at 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).................................................. 9-31

Figure 9.4.5.2b. Deciview and light extinction coefficients (bext, Mm-1) for ammonium sulfate, 

ammonium nitrate, and particulate organic mass (POM) for the baseline (2000–2004), period 1 

(2005–2009), and 2064 natural conditions estimates for the best 20% visibility days at Agua 

Tibia Wilderness, CA. Values of bext for other species, including elemental carbon (EC), soil, 

coarse mass, and sea salt are listed in the table below the graph (data and graphs obtained at 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).................................................. 9-31

Figure 9.4.5.3a. Class I Area –- Daily light extinction coefficients (bext, Mm-1) for ammonium 

sulfate (ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext), and sea salt 
xlii

IMPROVE REPORT V

(seasalt_bext) for 2002 at Agua Tibia Wilderness, CA (AGTI1). Worst 20% days are marked 

with a “W” above the bar for that day, and similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-32

Figure 9.4.5.3b. Class I Area –- Daily light extinction coefficients (bext, Mm-1) for ammonium 

sulfate (ammSO4f_bext), ammonium nitrate (ammNO3f_bext), particulate organic matter 

(OMCf_bext), coarse mass (CM_bext), elemental carbon (EC_bext), soil (soil_bext), and sea salt 

(seasalt_bext) for 2008 at Agua Tibia Wilderness, CA (AGTI1). Worst 20% days are marked 

with a “W” above the bar for that day, and similarly, best 20% days are marked with a “B” (from 

http://views.cira.colostate.edu/web/Composition/).................................................................... 9-32

Figure 10.1. Schematic of the particle generation, mixing, and sampling system used to make 

reference materials. A solution is atomized and the resulting particles are dried and mixed with 

clean, dry air in the mixing chamber. The suspended particles are drawn through an IMPROVE 

PM2.5 sampler and collected on 25 mm Teflon® filters. Relative humidity (RH) is measured in 

three locations to ensure that particles are anhydrous. ..............................................................10-2

Figure 10.2. Photograph of the aerosol generation system. .................................................. 10-2

Figure 10.3. Sulfur (S) mass measurements from ion chromatography (IC) compared to 

gravimetric analysis for ammonium sulfate and potassium sulfate reference materials. The linear 

regressions (with 95th percentile confidence levels for the slope and intercept) for each reference 

material are given on the figure and show the good agreement between sulfur from IC and 

gravimetric analysis. .................................................................................................................. 10-4

Figure 11.1. Study trailer showing aerosol sampling equipment. The CASTNET, Met tower, 

IMPROVE, URG, and passive samplers are shown from left to right. ..................................... 11-2

Figure 11.2. URG sampler with the NH3 backup denuder at top and filter pack, NH3 primary 

denuder, HNO3 denuder, and PM2.5 cyclone at bottom. Note the top of the sampler is the outlet 

and the bottom of the sampler is the inlet.................................................................................. 11-3

Figure 11.3. IMPROVE sampler filter cassette with additional screen and spacer for NH3

collection. The sampler includes 1) cassette filter holder, 2) Teflon spacer, 3) Teflon-coated 

support grid, and 4) top of cartridge assembly. ......................................................................... 11-4

Figure 11.4. IMPROVE sampler channel B with sample cassette installed. ........................ 11-4

Figure 11.5. CASTNET filter pack ready for deployment (left) and a disassembled filter pack 

(right). ........................................................................................................................................ 11-5

Figure 11.6. Regular (left) and modified (right) CASTNET filter packs in the sample holder.

.................................................................................................................................................... 11-5

Figure 11.7. Passive samplers deployed in the field. The Ogawa sampler is on the left, and the 

Radiello sampler is on the right. ................................................................................................ 11-6

Figure 11.8. Comparisons of sulfate ion (SO4

2-

) concentrations from the regular IMPROVE 

(RegIMP), modified IMPROVE (ModIMP), and URG samplers during fall 2008. Mean sulfate 

ion concentrations (μg m-3) for each sampler are reported. ....................................................... 11-7

Figure 11.9. Comparisons of nitrate ion (NO3

-

) concentrations from the regular IMPROVE 

(RegIMP), modified IMPROVE (ModIMP), and URG samplers during fall 2008. Mean nitrate 

ion concentrations (μg m-3) for each sampler are reported. ....................................................... 11-8
xliii

IMPROVE REPORT V

Figure 11.10. Comparisons of ammonium ion (NH4

+

) concentrations from the regular 

IMPROVE (Regular IMP), modified IMPROVE (Modified IMP), and URG samplers during fall 

2008. Mean ammonium ion concentrations (μg m-3) for each sampler are reported................. 11-9

Figure 11.11. Comparisons of ammonia (NH3) concentrations from the modified IMPROVE 

(Modified IMP) and URG samplers during fall 2008. Mean ammonia concentrations (μg m-3) for 

each sampler are reported. ....................................................................................................... 11-10

Figure 11.12. Comparisons of NHx (NH3 + NH4

+

) concentrations from the modified 

IMPROVE (Mod IMP) and URG samplers during fall 2008. Mean NHx concentrations (μg m-3) 

for each sampler are reported................................................................................................... 11-11

Figure 11.13. Comparisons of NHx (NH3 + NH4

+

) concentrations from the modified 

IMPROVE (IMP) and URG samplers during spring 2010. Mean NHx concentrations (μg m-3) for 

each sampler are reported. ....................................................................................................... 11-12

Figure 11.14. Comparisons of sulfate ion (SO4

2-

) concentrations from the modified CASTNET 

(Mod CASTNET), regular CASTNET (Reg CASTNET), and URG samplers during fall 2008. 

Mean sulfate ion concentrations (μg m-3) for each sampler are reported. ............................... 11-13

Figure 11.15. Comparisons of nitrate ion (NO3

-

) concentrations from the modified CASTNET 

(Mod CASTNET), regular CASTNET (Reg CASTNET), and URG samplers during fall 2008. 

Mean nitrate ion concentrations (μg m-3) for each sampler are reported................................. 11-14

Figure 11.16. Comparisons of nitric acid (HNO3) concentrations from the modified 

CASTNET (Mod CASTNET), regular CASTNET (Reg CASTNET), and URG samplers during 

fall 2008. Mean nitric acid concentrations (μg m-3) for each sampler are reported................. 11-15

Figure 11.17. Comparisons of total oxidized nitrogen concentrations (NO3

-

+ HNO3) from the 

modified CASTNET (Mod CASTNET), regular CASTNET (Reg CASTNET), and URG 

samplers during fall 2008. Total oxidized nitrogen concentrations (μg m-3) for each sampler are 

reported. ................................................................................................................................... 11-16

Figure 11.18. Comparisons of ammonium ion (NH4

+

) concentrations from the modified 

CASTNET (Mod CASTNET), regular CASTNET (Reg CASTNET), and URG samplers during 

fall 2008. Ammonium concentrations (μg m-3) for each sampler are reported........................ 11-17

Figure 11.19. Comparisons of ammonia (NH3) concentrations from the modified CASTNET 

(Mod CASTNET), and URG samplers during fall 2008. Ammonia concentrations (μg m-3) for 

each sampler are reported. ....................................................................................................... 11-18

Figure 11.20. Comparisons of total reduced inorganic nitrogen (NHx = NH3 + NH4

+

) 

concentrations from the modified CASTNET (Mod CASTNET) and URG samplers for 2008. 

NHx (μg m-3) for each sampler are reported. ........................................................................... 11-19

Figure 11.21. Comparison of weekly ammonia (NH3) concentrations (μg m-3) from URG and 

CASTNET samplers and 2-week concentrations from the Radiello and Ogawa passive samplers 

during 2008. ............................................................................................................................. 11-20
xliv

IMPROVE REPORT V

LIST OF TABLES

Table S.2.2. Comparisons between collocated IMPROVE and CSN sites for all data from 

2005 through 2008. Species include organic carbon (OC), light absorbing carbon (LAC), 

ammonium sulfate (AS), ammonium nitrate (AN), soil, sea salt, PM2.5 gravimetric fine mass 

(FM), and PM2.5 reconstructed fine mass (RCFM). “OCunadj” and “LACunadj” refer to 

comparisons between unadjusted CSN carbon data and IMPROVE carbon data; “OCadj” and 

“LACadj” refer tocomparisons between adjusted CSN carbon and IMPROVE carbon data. ......S-7

Table 1.1. Currently operating and discontinued IMPROVE particulate monitoring sites. The 

sites are grouped by region, as displayed in Figure 1.2. ..............................................................1-5

Table 1.2. Class I areas and the representative monitoring site.. .......................................... 1-11

Table 1.4. Transmissometer receiver and transmitter locations............................................ 1-21

Table 1.5. IMPROVE nephelometer network site locations. ................................................ 1-23

Table 1.6. Updated flow rate-related validation flag definitions and application criteria..... 1-34

Table 1.7. Major networkwide changes in sampling, analysis, and data reporting affecting 

samples collected January 2005 and later.................................................................................. 1-35

Table 1.8. Chemical Speciation Network (CSN) site location, setting and region. .............. 1-38

Table 1.9. Comparisons between collocated IMPROVE and CSN sites for all data from 2005 

through 2008. Species include organic carbon (OC), light absorbing carbon (LAC), ammonium 

sulfate (AS), ammonium nitrate (AN), soil, sea salt, PM2.5 gravimetric fine mass (FM), and PM2.5

reconstructed fine mass (RCFM). “OCunadj” and “LACunadj” refer to comparisons between 

unadjusted CSN carbon data and IMPROVE carbon data; “OCadj” and “LACadj” refer 

tocomparisons between adjusted CSN carbon and IMPROVE carbon data.............................. 1-44

Table 2.1. Form of molecular species assumed in this report. ................................................ 2-3

Table 2.1.3. The negative multiplicative artifact (M) and the monthly positive additive organic 

artifact (Amonth) used to adjust the CSN carbon concentrations for comparisons with IMPROVE. 

The units for the positive artifacts are g m-3and M is unitless. Adjustments are listed as a 

function of sampler (columns)..................................................................................................... 2-6

Table 6.1. Results from long-term (1989–2008) trend analyses for sulfate ion, total carbon 

(organic carbon + light absorbing carbon), fine soil, gravimetric fine mass, coarse mass, and 

PM10. The minimum and maximum slope (μg m-3yr-1) and trend (% yr-1) are provided, along 

with the site corresponding to the maximum and minimum........................................................6-7

Table 6.2. Results from short-term (2000–2008) trend analyses for sulfate ion, nitrate ion, 

total carbon (organic carbon + light absorbing carbon), fine soil, gravimetric fine mass, coarse 

mass, and PM10. The minimum and maximum slope (μg m-3yr-1) and trend (% yr-1) are provided, 

along with the site corresponding to the maximum and minimum............................................ 6-11

Table 8.1. Design specifications of the IMPROVE and CSN samplers. ...............................8-3

Table 8.2. The multiplicative artifact (1 + bOC) and the monthly positive organic artifact (a) 

used to relate the CSN and IMPROVE carbon concentrations. The units for the positive artifacts 

are g/m3 and 1 + bOC is unitless............................................................................................. 8-10
xlv

IMPROVE REPORT V

Table 8.3. Summary of the percent seasonal variability and average difference of 

reconstructed versus gravimetric mass. ..................................................................................... 8-19

Table 8.4a. Results of OLS regression analysis using equation 8.15 for the IMPROVE 

monitoring data. ......................................................................................................................... 8-21

Table 8.4b. Results of OLS regression analysis using equation 8.15 for the CSN/suburban 

monitoring data. ......................................................................................................................... 8-22

Table 8.4c. Results of OLS regression analysis using equation 8.15 for the CSN/urban 

monitoring data. ......................................................................................................................... 8-22

Table 9.4.2. 2018 Reasonable progress goals compared to baseline visibility and uniform rate 

of progress, from the Tennessee and North Carolina regional haze state implementation plans. ....

....................................................................................................................................................9-20

Table 9.4.3.1. Monitored, estimated, and projected 2018 visibility conditions and emissions 

changes for the worst 20% visibility days from WRAP regional analyses for Mesa Verde NP, CO 

(MEVE1) (from http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).......................9-22

Table 9.4.3.2. Monitored, estimated, and projected 2018 visibility conditions and emissions 

changes for the best 20% visibility days from WRAP regional analyses for Mesa Verde NP, CO 

(MEVE1) (from http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx).......................9-23

Table 9.4.4.1. Monitored, estimated, and projected 2018 visibility conditions and emissions 

changes for the worst 20% visibility days from WRAP regional analyses for Hell’s Canyon 

Wilderness Area, OR/ID (HECA1) (from 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx)..................................................9-28

Table 9.4.4.2. Monitored, estimated, and projected 2018 visibility conditions and emissions 

changes for the best 20% visibility days from WRAP regional analyses for Hell’s Canyon 

Wilderness Area, OR/ID (HECA1) (from 

http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx)..................................................9-29

Table 9.4.5.1. Monitored, estimated, and projected 2018 visibility conditions and emissions 

changes for the worst 20% visibility days from WRAP regional analyses for Agua Tibia 

Wilderness, CA (AGTI1) (from http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx). ....

....................................................................................................................................................9-33

Table 9.4.5.2. Monitored, estimated, and projected 2018 visibility conditions and emissions 

changes for the best 20% visibility days from WRAP regional analyses for Agua Tibia 

Wilderness, CA (AGTI1) (from http://vista.cira.colostate.edu/tss/Results/HazePlanning.aspx). ....

....................................................................................................................................................9-34