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PROCESSING CASTNET DETAILS              

DENE BOWDALO, Updated 29th April 2018

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PROCESSING NOTES

*Downloaded site metadata excel file (site.csv) from site category on: 
https://java.epa.gov/castnet/epa_jsp/prepackageddata.jsp, and renamed to CASTNET_META.csv

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NETWORK DESCRIPTION

CASTNET is a long-term environmental monitoring network with 95 sites located throughout 
the United States and Canada. CASTNET is managed and operated by the U.S. Environmental 
Protection Agency (EPA) in cooperation with the National Park Service (NPS); Bureau of 
Land Management, Wyoming State Office (BLM); and other federal, state, and local partners 
(www.epa.gov/castnet) including six Native American tribes that operate CASTNET sites on 
tribal lands. The network was established under the 1991 Clean Air Act Amendments to 
assess the trends in acidic deposition due to emission reduction programs such as the Acid 
Rain Program (ARP), NOx Budget Trading Program (NBP), the Clean Air Interstate Rule 
(CAIR), and the Cross-state Air Pollution Rule (CSAPR).

DESCRIPTION URL: https://www.epa.gov/castnet
     
DATA ACCESS URL: https://java.epa.gov/castnet/epa_jsp/prepackageddata.jsp

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QUALITY ASSESSMENT LEVEL (Sources: ozone_2017_tableinfo.csv and 
                                   hourly_gas_2017_tableinfo.csv)

QA_CODES (ASSOCIATED WITH EACH HOURLY MEASUREMENT)

0 - Level 0 validated data
1 - Level 1 validated data
1X - Level 1 data that are suspect based on manual screening. Data should be omitted from 
     any statistical analyses.
2 - Level 2 validated data
3 - Level 3 validated data
GS - Government shutdown period
X - Record not obtained via daily polling; placeholder used

**Data having a QA_CODE of less than 3 is preliminary and subject to change 
  --> Only Level 3 Validated data is accepted

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CONTACT

US EPA, Clean Air Markets Division, 1200 Pennsylvania Avenue, NW
Mail Code 6204M
Washington, DC 20460
puchalski.melissa@epa.gov

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AVAIALABLE SPECIES (DATA LAST ACCESSED: 26TH APRIL)

Ozone (1987-2018)
Nitric Oxide (2008-2018)
Nitrogen Dioxide (2014-2018)
Carbon Monoxide (2008-2018)

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FORMAT

The data files are single annual files, including all sites. For ozone, files are separate 
,for NO, NO2 and CO the files are mixed together

Each row gives an hourly measurement at one site, for a single species

Metadata is given originally in an external excel spreadsheet: sites.csv 
(converted to csv), with data for each site per line

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METADATA/DETAIL FILES

CORE
CASTNET_META.csv

OTHER
CASTNET_background.pdf 
CASTNET_2017_ANNUAL_NETWORK_PLAN.pdf  
CASTNET_QUALITY_ASSURANCE_PROJECT_PLAN.pdf  
CASTNET_TRACEGAS_QA.pdf  
ozone_2017_columninfo.csv
ozone_2017_tableinfo.csv
hourly_gas_2017_columninfo.csv  
hourly_gas_2017_tableinfo.csv 
site.csv
site_columninfo.csv  
site_tableinfo.csv

INSTRUMENT MANUALS

O3
Thermo_49C_Manual.pdf
Thermo_49i_Manual.pdf

NOx 
Teledyne_T200_Manual.pdf
Teledyne_T200U_addendum.pdf
Teledyne_T200U-NOy_addendum.pdf 
Thermo_42i-NOy_Manual.pdf

CO
Teledyne_T300U_Manual.pdf 
Thermo_48i-TLE_Manual.pdf


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DATAFILE VARIABLES

Ozone:

SITE_ID - Site identification code
DATE_TIME - Date and time sample collection began, Local Standard Time mm/dd/yyyy hh:mm:ss
OZONE - Ozone concentration (ppbv)
OZONE_F - Data quality code for OZONE
QA_CODE - Quality assurance level of the record.
UPDATE_DATE - Date and time of last record update

Nitric Oxide and Carbon Monoxide: 

SITE_ID - Site identification code
DATE_TIME - Date and time sample collection began, Local Standard Time mm/dd/yyyy hh:mm:ss
PARAMETER - Abbreviated chemical symbol of parameter measured
(NO=nitric oxide, NO2_TRUE=nitrogen dioxide, CO=carbon monoxide)
VALUE - Numeric value of parameter measured (ppbv)
VALUE_F - Data quality code for VALUE
QA_CODE - Quality assurance level of the record.
UPDATE_DATE - Date and time of last record update 

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METADATA VARIABLES

SITE_ID - Site identification code
SITE_NUM - Numeric unique site identification
SITE_NAME - Site name
ACTIVE - Sampling operations currently being conducted at site, site is inactive if NULL.
INACTIVE - Sampling operations that have previously been conducted at the site but are not 
           currently being performed
AGENCY - Operating agency
STATE - State abbreviation
COUNTY - County
TIME_ZONE - Local time zone of site
LATITUDE - Latitude (decimal degrees)
LONGITUDE - Longitude (decimal degrees)
ELEVATION - Elevation (m)
MAPID - USGS 7-1/2 min. map name.
LAND_USE - Primary land use
TERRAIN - Terrain surrounding site
MLM - Does site conform to assumptions of MLM?
NADP_ID - NADP site code
NADP_DISTANCE - Distance to nearest NADP site
UPDATE_DATE - Date and time of last record update

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UNITS (Sources: ozone_2017_columninfo.csv and hourly_gas_2017_columninfo.csv)

Ozone             ppbv  
Nitric Oxide      ppbv
Nitric Dioxide    ppbv
Carbon Monoxide   ppbv

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UNIT PRECISION (Sources: CASTNET_QUALITY_ASSURANCE_PROJECT_PLAN.pdf, 
                         CASTNET_TRACEGAS_QA.pdf, Thermo_49C_Manual.pdf, 
                         Thermo_49i_Manual.pdf, Teledyne_T200U_addendum.pdf, 
                         Teledyne_T200U-NOy_addendum.pdf, Thermo_42i-NOy_Manual.pdf, 
                         Teledyne_T300U_Manual.pdf, Thermo_48i-TLE_Manual.pdf and 
                         checked data files)

Ozone             

Thermo 49C     1.0 or 2.0 ppbv  **given in 1.0 ppbv intervals, but states precision of 
                                +=2.0ppbv in CASTNET_QUALITY_ASSURANCE_PROJECT_PLAN.pdf
                                ,however precision stated as 1.0 ppbv in manual 
                                (Thermo_49C_Specs.pdf) 
                                
Thermo 49i     1.0 or 2.0 ppbv  **given in 1.0 ppbv intervals, but states precision of 
                                +=2.0ppbv in CASTNET_QUALITY_ASSURANCE_PROJECT_PLAN.pdf
                                ,however precision stated as 1.0 ppbv in manual 
                                (Thermo_49i_Specs.pdf) 
                                   
Nitric Oxide      

Teledyne T200U-NOy   0.5% of reading above 5 ppbv (~0.025ppbv at 5ppbv, ~0.1ppbv at 
                     20ppbv) **(Teledyne_T200U_addendum.pdf,
                             Teledyne_T200U-NOy_addendum.pdf) 
                
Thermo 42i-NOy       ---    **not given for Thermo 42i-NOy (Thermo_42i-NOy_Manual.pdf)

Nitrogen Dioxide  

No given instrument names   **HOWEVER, in data files is given to 3 decimal places, so can 
                            make assumption it is approximately similar to NO.

Carbon Monoxide   

Teledyne T300U    0.5% of reading (~0.1ppbv at 20ppbv, ~0.5ppbv at 100ppbv) 
                  **(Teledyne_T300U_Manual.pdf)
                  
Thermo 48i-TLE    ---       **not given for Thermo 48i-TLE (Thermo_48i-TLE_Manual.pdf)

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LIMIT OF DETECTION (Sources: CASTNET_TRACEGAS_QA.pdf, Thermo_49C_Manual.pdf, 
                             Thermo_49i_Manual.pdf, Teledyne_T200U_addendum.pdf, 
                             Teledyne_T200U-NOy_addendum.pdf, Thermo_42i-NOy_Manual.pdf, 
                             Teledyne_T300U_Manual.pdf, Thermo_48i-TLE_Manual.pdf and 
                             checked data files)

**Defined as twice the zero noise level by the US EPA - and is typically reported as such

Ozone             

Thermo 49C     1.0 ppbv  **(Thermo_49C_Specs.pdf)
                                
Thermo 49i     0.5 ppbv  **(Thermo_49i_Specs.pdf)
                                   
Nitric Oxide      

Teledyne T200U-NOy   0.05 ppbv  **(Teledyne_T200U_addendum.pdf, 
                                   Teledyne_T200U-NOy_addendum.pdf)
                
Thermo 42i-NOy       0.05 ppbv  **(Thermo_42i-NOy_Manual.pdf)

Nitrogen Dioxide  

No given instrument names   **HOWEVER, must be low as have seen as low as 0.065 ppbv 
                            reported in data files, therefore can make assumption it is 
                            similar to NO --> 0.05ppbv

Carbon Monoxide   

Teledyne T300U    <20.0ppbv   **(Teledyne_T300U_Manual.pdf)
                  
Thermo 48i-TLE     40.0ppbv   **(Thermo_48i-TLE_Manual.pdf)

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REPRESENTIVITY (Source: site.csv, CASTNET_QUALITY_ASSURANCE_PROJECT_PLAN.pdf )

SITE TYPES:
None Given

LOCAL LAND USE CLASSIFICATION (Dominant radius within 1km) 
Agric
Arid
Coastal
Coastal/Marsh
Desert
Forest
Forest/Arid
Forest/Marsh
Forest/Tropical
Marsh
Prairie
Range
Tropical
Urban
Urban/Agric

LEVELS OF URBANISATION:
None Given

NEIGHBOURHOOD POPULATION 
None Given

SCALE OF REPRESENTATIVENESS
None Given

TERRAIN
Coastal
Complex
Flat
Flat/Water
Mountaintop
Rolling
Water

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MEASUREMENT METHODLOGIES (Sources: CASTNET_QUALITY_ASSURANCE_PROJECT_PLAN.pdf,
                                   CASTNET_TRACEGAS_QA.pdf, hourly_gas_2017_tableinfo.csv,
                                   Thermo_49C_Manual.pdf, Thermo_49i_Manual.pdf, 
                                   Teledyne_T200_Manual.pdf, Teledyne_T200U_addendum.pdf, 
                                   Teledyne_T200U-NOy_addendum.pdf, 
                                   Thermo_42i-NOy_Manual.pdf, Teledyne_T300U_Manual.pdf 
                                   and Thermo_48i-TLE_Manual.pdf)

Ozone - continuous (1 hour average), ultraviolet photometry 

Nitric Oxide - continuous (1 hour average), chemiluminescence

Nitrogen Dioxide - continuous (1 hour average), chemiluminescence (conversion-photolysis)
** states conversion is photolysis in hourly_gas_2017_tableinfo.csv (checked other yearly 
files too, and is same). No other documentation is given for NO2 instrumentation. Both
possible NO instruments only measure NO/NOy using an external molybdenum converter, that 
is to say if they report NO2 it is significantly biased (Teledyne_T200_Manual.pdf, 
Teledyne_T200U_addendum.pdf, Teledyne_T200U-NOy_addendum.pdf and 
Thermo_42i-NOy_manual.pdf).

Carbon Monoxide - continuous (1 hour average), non-dispersive infrared spectroscopy

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INSTRUMENT NAME/MODEL NUMBERS (Sources: CASTNET_QUALITY_ASSURANCE_PROJECT_PLAN.pdf,
                                        CASTNET_TRACEGAS_QA.pdf, Teledyne_T200_Manual.pdf, 
                                        Teledyne_T200U_addendum.pdf, 
                                        Teledyne_T200U-NOy_addendum.pdf, 
                                        Thermo_42i-NOy_Manual.pdf)

Not measurement/site specific

Ozone:
Thermo 49C  
Thermo 49i
        
Nitric Oxide:    
Teledyne T200U-NOy (external molybdenum converter)
Thermo 42i-NOy (external molybdenum converter)

Nitrogen Dioxide:
None Stated
              
Carbon Monoxide:   
Teledyne T300U 
Thermo 48i-TLE

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NETWORK DATA FLAGS (WITH PERSONAL ACCEPTANCE CODES)        *A*=ACCEPTED   *N*=NOT ACCEPTED
(Sources: CASTNET_QUALITY_ASSURANCE_PROJECT_PLAN.pdf, ozone_2017_tableinfo.csv and 
          hourly_gas_2017_tableinfo.csv)

<     Missing < 25% of hourly sampling period
      deemed Valid by CASTNET *N*

A     Anomalous value resulting from local anthropogenic activity
      deemed Valid by CASTNET *A*

B     Field instrument channel down for > 75% of hourly sampling period 
      deemed Invalid by CASTNET *N*

C     Invalid data due to field calibration of instrument  
      deemed Invalid by CASTNET *N*
      
D     Field instrument channel down for 25% to 75% of hourly sampling period
      deemed Invalid by CASTNET *N*

E     Exceptional event designation requested by state agency
      deemed Valid by CASTNET *A*

F     Field instrument power failure
      deemed Invalid by CASTNET *N*

I     Invalid reading
      deemed Invalid by CASTNET *N*

K     Non-nominal flow value identified during automated screening
      deemed Valid by CASTNET *A*

M     Field data missing
      deemed Invalid by CASTNET *N*
      
N     Sampling time inadequate to calculate hourly average
      deemed Invalid by CASTNET *N*

NULL  Valid data
      deemed Valid by CASTNET *A*

P     Potential problem identified during automated screening requiring further 
      investigation
      deemed Invalid by CASTNET *N*
      
R     Indicates that the QC check is valid but that associated ambient measurements are 
      not valid and the check should not be submitted as a 1-point QC check to AQS.
      deemed Invalid by CASTNET *N*

S     Field instrument out of DQO at time of 2nd calibration
      deemed Valid by CASTNET *A*
      
U     Concentration below reporting limit for analyzer
      deemed Valid by CASTNET *N*

Z     < and U flags apply
      deemed Valid by CASTNET *N*

^     Alarm high -- ozone > 120
      deemed Valid by CASTNET *A*

_     Field reading less than zero
      deemed Valid by CASTNET *N*

MISSING DATA FILL = EMPTY FIELD

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EXTRA DETAILS

Ozone Measurements

O3 is measured via UV absorbance. The principle of operation is based on the Beers Law 
technique of UV absorption. EPA-sponsored sites primarily use Thermo Scientific Model 49i 
analyzers operating on the 0 to 250 parts per billion (ppb) ranges. Thermo Scientific 49C 
and 49i analyzers are used as primary (i.e., Level 2) standards in the Amec Foster Wheeler 
ozone calibration laboratory. Ambient air is drawn from the inlet on the 10-m air 
monitoring tower through 1/4-inch tetrafluoroethylene (TFE) Teflon tubing. EPA-sponsored 
sites use Savillex 47- mm filter holders to house 5-μm Teflon filters located at the tower 
inlet to help prevent particle deposition within the system. Sites are also equipped with 
Campbell Scientific model 107 temperature probes located inside near the analyzer for 
continuous monitoring and recording of shelter temperatures to ascertain compliance with 
Part 58 instrument environmental criteria. Table 2-10 lists the Thermo Scientific O3 
analyzers’ operating specifications.

Every six months, a multipoint calibration is performed to verify the response of the 
on-site instrument via comparison with the output of an O3 transfer standard. Each 
EPA-sponsored site utilizes a second in-station photometer with Level 3 transfer standard 
authority. This on-site transfer standard contains an internal ozone generation system 
that is used to generate the calibration gas during the semiannual calibration. Six points 
are checked from zero to 90 percent of the full-scale output of the ozone analyzer using 
the detector in a traveling transfer standard with Level 2 authority. The internal ozone 
generator is then set to perform automatic daily z/s/p checks of the ozone measurement 
system. The O3 calibration results are recorded on an electronic Ozone Calibration Form 
(see Figure 2-13).

The traveling transfer standards used for the multipoint calibrations of EPA-sponsored 
sites are verified annually by NIST reference photometer and audited at least twice per 
calendar quarter against a primary standard maintained in the Amec Foster Wheeler field 
instrumentation laboratory, which is discussed in Section 2.6. The primary standard is 
verified annually against the standard reference photometer at the EPA Region 7 
laboratory, known as the Kansas City Science & Technology Center (KCSTC). Please refer to 
Figure 2-14. Copies of the certification documentation are filed at each site and at Amec 
Foster Wheeler along with the calibration results for each site.

Automatic z/s/p checks are performed using the second in-station photometer to verify 
ozone levels used for the z/s/p checks. The results of the z/s/p checks are recorded by 
the Campbell CR3000 data logger and uploaded to the Amec Foster Wheeler CASTNET DMC server 
through routine hourly polls. The daily z/s/p checks are displayed (Figure 2-15) and 
reviewed by a data analyst and a field coordinator. The z/s/p binary files are named and 
managed similarly to the binary data files.

Trace Gas Measurements

CASTNET is a long-term environmental monitoring network that measures changes in ambient 
air quality and assesses atmospheric deposition across the United States. Operating since 
1987, CASTNET has evolved into a national monitoring program that consists currently of
89 monitoring stations nationwide as of June 2013. EPA operates a majority of the CASTNET 
monitoring stations. The National Park Service (NPS) operates 24 of the 89 stations in 
cooperation with EPA. CASTNET stations measure rural, regionally representative 
concentrations of sulfur and nitrogen pollutants and ozone (O3) in order to detect and 
quantify trends, define the geographic distribution of rural pollutants, and estimate dry 
deposition of pollutants. CASTNET sites are well suited to host NCore measurements because 
of their rural, regional characteristics and extensive existing infrastructure.