Appendix A: 

Back Trajectory Analysis of Beta Extinction 
Table 1 below presents the bext summary statistics by year for selected pollutants at the Cape 

Romain (45-019-0046) monitoring station. Data was accessed via the VIEWS 2.0 Data Wizard 

(http://views.cira.colostate.edu/web/DataWizard/) utilizing the IMPROVE Aerosol, RHR 

(New Equation) dataset. 

Table 1: Extinction Summary Statistics for Cape Romain 

Parameter 

bext

Year Minimum Maximum Median Arithmetic 

Mean 

Standard 

Deviation 

2006 10.92 215.52 46.24 60.30 44.04 

2007 5.35 327.53 31.83 46.85 45.05 

2008 6.98 132.49 34.92 40.49 25.90 

2009 2.53 110.65 29.53 33.00 19.13 

AMM. SO4

2010 6.59 92.86 29.03 33.65 16.63 

2006 0.77 14.21 3.05 3.83 2.34 

2007 0.64 16.77 3.93 4.52 2.65 

2008 0.69 19.12 3.91 4.52 2.90 

2009 0.33 12.78 3.23 3.85 2.54 

AMM. NO3

2010 0.80 15.63 3.73 4.31 2.91 

2006 0.20 38.01 8.98 10.54 7.45 

2007 1.24 69.62 7.50 10.54 9.07 

2008 0.88 33.95 7.31 8.88 5.84 

2009 0.84 30.70 6.59 7.93 5.45 

POM 

2010 1.04 149.08 7.02 10.36 15.09 

2006 0.00 13.56 3.71 3.99 2.75 

2007 0.00 12.22 2.48 3.17 2.49 

2008 0.00 12.48 2.28 2.59 2.03 

2009 0.02 7.91 2.06 2.26 1.50 

EC 

2010 0.03 15.07 2.27 2.88 2.41 

2006 0.04 6.77 0.36 0.62 0.90 

2007 0.04 6.00 0.39 0.58 0.74 

2008 0.03 7.56 0.44 0.69 0.92 

2009 0.01 6.30 0.39 0.66 0.96 

SOIL 

2010 0.08 12.71 0.43 0.74 1.34 

2006 0.03 9.74 3.07 3.26 1.81 

2007 0.28 12.90 3.60 3.83 1.87 

2008 0.51 11.99 3.01 3.41 1.84 

2009 0.31 9.80 3.14 3.35 1.71 

CM 

2010 0.34 17.09 3.23 3.56 2.32 

2006 0.00 40.31 0.65 3.29 6.81 

2007 0.00 31.75 0.95 2.92 4.67 

2008 0.00 36.38 0.88 4.06 7.50 

2009 0.00 20.98 0.76 2.81 4.27 

SEA SALT 

2010 0.00 21.01 0.34 2.10 4.07 

Percent change in Arithmetic Mean 

Table 2 indicates that during the 5-year period examined for the mid-course review, most of the 

bext averages decreased. The largest percent decrease was in bext values for ammonium sulfate, 

most likely due to the increase in controls installed on facilities in the region. POM, which can 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 1
be used as an indicator of emissions due to fires, remained relatively unchanged through the 

period. 

Table 2: Percent Change in Arithmetic Mean for Major Haze Components at Cape 

Romain 

Parameter Percent Change 

(2006 – 2010) 

AMM. SO4 -44% 

AMM. NO3 13% 

POM -2% 

EC -28% 

SOIL 20% 

CM 9% 

SEA SALT -36% 

The graphic below contains the 5-year average bext values for the major components of regional 

haze at Cape Romain. After ammonium sulfate (64.1%), the next largest fraction of regional 

haze at Cape Romain is POM (14.4%) which is one of the indicators of impacts from smoke. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 2
Figure 1: Five-Year Beta Extinction for Major Haze Components at Cape Romain 

As stated above, bext values for sulfate have been reduced during the 2006 – 2010 time period. 

Time series graphs for the major regional haze components are presented below. Spikes seen in 

the POM time graph suggest impacts from fires and will be discussed in the next section. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 3
SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 4
High POM (or OMC) concentrations are one of three indicators of fire impacts. In addition to 

POM, ambient concentrations of EC1

 and non-soil potassium (KNON)2 should be examined. 

According to the IMPROVE website: 

“Fine potassium has two major sources, soil and smoke, with the smoke 

potassium on much smaller particles than the soil potassium. The potassium in 

coarse particles will be solely produced from soil. The soil potassium is estimated 

from the measured concentration of Fe and the ratio of K/Fe of 0.6 measured on 

coarse samples (2.5 to 15 μm) collected between 1982 and 1986. This ratio 

depends on the soil composition and varies slightly from site to site. If the ratio 

were slightly smaller (say 0.5), the KNON values will be negative when there is 

no smoke influence. The residual potassium, K - 0.6*Fe, is then assumed to be 

produced by smoke. The burning of most organic fuels will produce potassium 

vapor. During transport, this vapor will transform into fine particles. The KNON 

parameter is not a quantitative measure of the total smoke mass, since the ratio of 

nonsoil potassium to total smoke mass will vary widely, depending on the fuel 

type and the transport time. However, the KNON parameter can be used as an 

indicator of a nonsoil contribution for samples with large KNON. In some 

situations there may be some fine Fe from industrial sources which could cause 

occasional smoke episodes to be lost.”2

The top five POM bext values were examined in order to determine if there were potential 

impacts from fires. These dates and time were then cross referenced using the University of 

Maryland Baltimore County’s (UMBC) US Air Quality Weblog (USAQ) – “Smog Blog.” The 

USAQ is a daily diary of air quality in the U.S. prepared using information from satellites, 

ground-based measurements, and models. Interpretation and analysis are provided by the staff of 

the UMBC, Atmosphere Lidar Group.3 To conduct this analysis, back trajectories, examination 

of EC, POM and KNON for the two samples prior to immediately proceeding the high bext day 

and entries from “The Smog Blog”4 were examined. 

Table 3 contains the dates and values for the five highest POM bext sampling events at Cape 

Romain. 

 

1

 Email communication with Dr. James Boylan, Georgia Department of Natural Resources, June 11, 2012. 

2

 http://vista.cira.colostate.edu/improve/Tools/AerTypeEqs.htm. 

3

 UMBC, US Air Quality Weblog, http://alg.umbc.edu/usaq/, last accessed on June 14, 2012. 4

 http://alg.umbc.edu/usaq/ 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 5
Table 3: Five Highest POM Days at Cape Romain (2006-2010) 

Date POM bext value 

(Mm-1) 

11/19/2010 149.08 

5/3/2007 69.61 

4/2/2010 51.47 

2/17/2007 46.54 

3/9/2010 44.09 

Thirty-six hour back trajectories were run using the HYSPLIT (Hybrid Single Particle 

Lagrangian Integrated Trajectory) model for the Cape Romain monitoring site (45-019-0046) 

located in Charleston County on the five highest POM bext days from 2006 - 2010. 

The back trajectories were run using the NAM (North American Mesoscale Model) Eta Data 

Assimilation System (EDAS) 40 kilometer grid at four different vertical heights (10 meters, 300 

meters, 500 meters, and 1000 meters). Back trajectory meteorological files are downloaded from 

the National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory 

website (ftp://arlftp.arlhq.noaa.gov/pub/archives/edas40). 

The following section of text provides a more detailed explanation and review of the five highest 

POM bext days from 2006-2010. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 6
November 19, 2010 (POM bext: 149.08 Mm-1)

The lowest level back trajectory shows air moving slowly from North Carolina southward to the 

coast then down the coast to the Cape Romain monitor. The mid-level trajectories shows air 

moving out of the Ohio River Valley to the Mid-Atlantic coast then southward down the coast to 

the Cape Romain monitor. The upper-level trajectory shows air moving from eastern Tennessee 

and western North Carolina to the Atlantic coast then south to Cape Romain. 

An examination of EC, POM and KNON ambient concentrations during the high bext day shows 

an increase in all three parameters as compared to prior and subsequent measurements. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 7
Smog Blog entry: 

FIRES AND CODE ORANGE PM2.5 LEVELS IN GEORGIA 

AND FLORIDA; CONTINUING BAD AIR QUALITY IN 

CALIFORNIA 

PM2.5 levels (top left, courtesy AIRNow) across the country were mostly 

good wit exception to the southern region of the country and California. In 

the south, NOAA's Hazard Mapping System (HMS, top right) reports 

smoke and fires in Georgia, Florida, Alabama, North and South Carolina. 

Smoke from fires in Georgia and Alabama were observed by the MODIS 

TERRA true color image (bottom). PM2.5 levels in these states were 

mostly Code Yellow (Moderate). Code Orange (Unhealthy for sensitive 

Groups) PM2.5 levels were observed in Georgia, Florida, and South 

Carolina. Code Red (Unhealthy) PM2.5 levels were reported in Georgia, 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 8
just above the Florida state line. In California, Code Orange and Code Red 

PM2.5 levels were reported today. Due to cloud coverage across the state, 

HMS was unable to detect any fires that may be continuing to burn and 

affect the local air quality, as have been reported on this blog for the past 

couple of days. 

In other parts of the country, smoke from fires was reported off the coast 

of North Carolina ad in Texas. A plume of smoke was reported in western 

Texas, however there are no fires in the vicinity. 

Posted by Jaime Compton at 7:50 PM | Comments (0)

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 9
May 3, 2007 (POM bext: 69.61 Mm-1) 

The back trajectory analysis in the lower and mid-levels show air parcels originating off the 

southeast coast and northeastern Florida, moving northward up the coast and to Cape Romain. 

The upper-level trajectory shows air originating across southwestern Georgia, moving up 

through south-central Georgia, across south-central South Carolina to Cape Romain. 

An examination of EC, POM and KNON ambient concentrations during the high bext day shows 

an increase in all three parameters as compared to prior and subsequent measurements. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 10
Smog Blog entry: 

OTHER COVERAGE OF THE FIRES IN GEORGIA 

Our colleagues at the Cooperative Institute for Meteorological Satellite 

Studies (CIMSS) at the University of Wisconsin have also been covering 

the fires in Georgia. Check out the posts on their meteorological blog about 

the smoke today and a multi-day analysis a couple days ago. 

Posted by Jill Engel-Cox at 11:37 PM

SMOKE COVERS THE SOUTHEAST U.S. AND GULF OF 

MEXICO 

The fires continued in Georgia and the smoke intensified to cover the 

entire U.S. southeast coast, including Florida, Georgia, South Carolina, 

and North Carolina. Aerosol optical depth values exceed 1.0 and PM2.5 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 11
values finally reached code red (unhealthy) levels, with Jacksonville, 

Florida at about 80 ug/m3. 

Further south and west, there were major (agricultural?) fires in southern 

Mexico producing considerable smoke. GOES aerosol optical depth levels 

were over 1.0 over the Gulf of Mexico. 

Posted by Jill Engel-Cox at 10:27 PM

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 12
April 2, 2010: (POM bext: 51.47 Mm-1)

The back trajectory analysis shows air moving northward from near the Georgia coast or just off 

the Georgia coast to Cape Romain. 

An examination of EC, POM and KNON ambient concentrations during the high bext day shows an 

increase in all three parameters as compared to prior and subsequent measurements.

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 13
Smog blog entry: 

MODERATE LEVELS OF PM2.5 IN EAST COAST; FIRES IN 

SOUTH 

Today, air quality throughout the country was mostly good. PM2.5 levels 

(top left, courtesy AIRNow) on the eastern coast of the country was 

mostly reached Code Yellow (Moderate). Code Orange (Unhealthy for 

Sensitive Groups) PM2.5 levels were reported in Georgia, Alabama, South 

Carolina, and Texas in the morning hours. NOAA's Hazard Mapping 

System (HMS, top right) reports a large amount of fires in the southern 

region of the country. Smoke plumes were reported in South Carolina, 

Georgia, Florida, Alabama, Mississippi, Kentucky, Tennessee, North 

Carolina and Virgina. Several of the smoke plumes in the southern states 

of Alabama, Georgia, and Florida were observed by the MODIS AQUA true 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 14
color image (top right). The red dots in the image represent the locations 

of the fires. Smoke can be seen coming from several of these locations. 

These fires and their smoke plumes could be a possible cause for the 

elevated PM2.5 levels in the region. There was also high AOD levels 

reported in the Midwest today. A possible cause for the high AOD reading 

is the clouds in the region. AOD levels in South Carolina were also 

reported to be moderate to high. 

Ozone levels are beginning to rise again as the weather is warming. Ozone 

levels today were good throughout the country with some small areas 

experiencing Code Yellow levels. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 15
Posted by Jaime Compton at 4:31 PM | Comments (0)

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 16
February 17, 2007: (POM bext: 46.54 Mm-1) 

The mid and low-level back trajectories show air moving southward from south-central North 

Carolina and north-central South Carolina to the south coast of South Carolina then moving up 

the coast to Cape Romain. The upper-level trajectory shows air moving southward out of 

southeastern Tennessee, southeastward across eastern Georgia to the south coast of South 

Carolina then northeastward to Cape Romain. 

An examination of EC, POM and KNON ambient concentrations during the high bext day shows 

an increase in all three parameters as compared to prior and subsequent measurements. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 17
Smog Blog entry: Note, no mention of fires on 2/17/2007, but the next blog entry made 

reference to fires visible on the NOAA Hazard Mapping System. 

FIRES IN THE SOUTH 

Very good air quality with just one moderate fine particle reading in 

Maine and a few in the central valley of California. The southeast U.S. was 

clear in the morning, but there were many small fires visible in the 

afternoon MODIS image (left), especially Oklahoma, Louisiana, 

Mississippi, Georgia, and Florida. NOAA Hazard Mapping System 

identified many fires and smoke plumes (right) and GOES had elevated 

aerosol optical depth values. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 18
Posted by Jill Engel-Cox at 8:59 PM

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 19
March 9, 2010: (POM bext: 44.09 Mm-1) 

The lower and mid-level back trajectories show air moving up from southeast Georgia, up the 

South Carolina coast to Cape Romain. The upper-level trajectory shows air moving southward 

from northeast Georgia to southeast Georgia then back up the South Carolina coast to Cape 

Romain. 

An examination of EC, POM and KNON ambient concentrations during the high bext day shows 

an increase in all three parameters as compared to prior and subsequent measurements. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 20
Smog blog entry: 

CODE ORANGE PM2.5 AIR QUALITY IN THE MIDWEST 

PM2.5 air quality conditions worsened today in the upper Midwest, with 

Code Orange (Unhealthy for Sensitive Groups) readings widespread across 

Minnesota, Wisconsin, Illinois, Indiana, and Ohio. Elsewhere in the 

nation, including the Northeast and West Coast, air quality was generally 

Code Green (Good). A ridge of high pressure has been situated over the 

Great Lakes/Ohio River Valley for the past few days, which has created 

stagnant conditions that have allowed pollutants to accumulate, including 

smoke from agricultural fires burning in the Southeast. It is possible to 

discern the hazy and smoky airmass over the Midwest, Ohio River Valley, 

and Southeast in today's MODIS Terra true color image (below on lower 

left, overlaid with AQI values and the synoptic analysis). Clouds from an 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 21
approaching low pressure system blocked AOD measurements over much 

of the Midwest today, but the MODIS Aqua image (below on lower right, 

courtesy of IDEA) shows areas of elevated AOD in Ohio/West Virginia and 

North Carolina associated with the haze/smoke. Southwesterly flow ahead 

of the low pressure system will push the polluted airmass into the MidAtlantic on Wednesday, and both Baltimore and the Liberty/Clarion area 

outside of Pittsburgh have issued Air Quality Action Days for expected 

Code Orange PM2.5 air quality. Moderate air quality will likely linger in 

the Midwest on Wednesday, then improve with the passage of the low 

pressure system. 

Posted by Amy Huff at 8:43 PM | Comments (0)

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 22
March 8, 2010 

AIR QUALITY WORSENS IN THE US 

(MIDWEST/CENTRAL/SOUTH/NORTHEAST) 

The air quality (AIRNow; top, left) in almost half the country was mostly 

in the moderate range. In the upper Midwest - Minnesota and Wisconsin - 

unhealthy levels (for sensitive groups) of PM2.5 were recorded in the 

morning and it persisted throughout the day in Eastern Wisconsin. 

California enjoyed good air quality today. 8h ozone levels loop can be 

checked here. 

The smoke due to the agricultural fires in the Southeastern US (HMS fires 

map here) could still be observed over the Midwest (MODIS Terra; top, 

right) as well as higher AOD values (MODIS Aqua; bottom, left). 

Tropospheric NO2 concentrations were higher today over New York, 

Cleveland, St Louis and Pittsburgh (OMI; bottom, right). 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 23
According to AIRNow's website, tomorrow's highest forecasts (code orange) 

are for Chicago, Hammond-Gary in Indiana, Liberty/Clairton area in 

Pennsylvania and Minneapolis-St Paul area and Rochester both in 

Minnesota. Action Days were issued for all those areas. 

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 24
Posted by Patricia Sawamura at 11:56 PM | Comments (0)

SC SIPR: Regional Haze Periodic Update Appendix A December 2012 - Page 25