Quick Links

• Meteorological Data
• Ozone Data
• NO₂ Data
• Monitoring Background Values
• Modeling Guidance
• Modeling Resources

The District no longer accepts analyses performed using the Industrial Source Complex –
Short-Term (ISCST3) model.

All meteorological data have been processed with AERMET, Version 06341.

Meteorological Data (Only for use in the AERMOD model)

All meteorological data sets are draft at this time but should be used for any modeling of sources in the San Joaquin Valley. Please download the latest data sets before modeling. Use the most recent five years of meteorological data. Model all five years. Use all the data available for a site if less than five years of data are available. For a cancer or a chronic non-cancer risk assessment, the average cancer risk of all years modeled should be used. If concatenated data sets are used for an analysis of compliance with ambient air quality standards, the 5-year average concentration obtained by running a concatenated data set shall be multiplied by a factor of 1.5 except for Bakersfield, Hanford, and Modesto. For those three data sets, a factor of 1.75 shall be used. If a violation of an annual average standard is predicted using this approach, the project can be remodeled using each year's data set. Then, the maximum annual average concentration predicted will be compared to annual average standard.

Meteorological data are available from two sources: 1) the National Climatological Data Center (NCDC) and 2) the MM5 Numerical Model. NCDC data were collected at major airports in the Valley. These data can be used for health risk assessments and ambient air quality analyses. The data derived from the MM5 numerical model are for sites where there are no airports. These sites are in the western part of the Valley. MM5- derived data can be used for health risk assessments. They cannot be used for ambient air quality analyses.

Ozone Data (Only for use in the AERMOD model)**

To use file click on link and pick Save As to save to your PC

County

For information about each of these sites please refer to ARB's Quality Assurance Air Monitoring Site Information.

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Nitrogen Dioxide Data (Only for use in performing a Tier IV or paired sums analysis)**

To use file click on link and pick Save As to save to your PC

County

To download the District’s guidance on developing “EPA’s NO₂ Modeling Background Datasets”. Click here.

For information about each of these sites please refer to ARB's Quality Assurance Air Monitoring Site Information.

Contact the District before performing a Tier IV or paired sums analysis!

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Monitoring Background Values

1-Hour NO₂

The District has processed the NO₂ monitoring data for all sites located within the San Joaquin Valley using the guidance provided in Appendix S of Part 50. A detailed description of the District’s procedure and a summary of the data used can be downloaded here.

1-Hour SO₂

The District has processed the SO₂ monitoring data for all sites located within the San Joaquin Valley using the guidance provided in Appendix T of Part 50.

Other Background Values

All other background values can be downloaded from EPA at http://www.epa.gov/airdata/ad_rep_mon.html.

Corrections

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Modeling Guidance

• PSD Modeling Guidance - DRAFT (March 2013)
• Draft Modeling Guidance: Larger files with pictures (1.7mb)    Smaller file with no pictures (0.9mb)

This document is a working draft. It can be used for preparing modeling and/or health risk assessment protocols. Because it is a working draft, please contact District personnel at HRAModeler@valleyair.org prior to using this guidance document to ensure that the latest version is being used.
• Procedure For Determining NO2 Monitor Background Values (Design Values) For Use In Calculating NAAQS Compliance (606 kb)
• Assessment of Non-Regulatory Options in AERMOD Specifically OLM and PVMRM (552 kb)
  The District has developed an MS Access DB which implements the Tier III and Tier IV procedures outlined in the above document. The program is free of charge and is provided as is. If you would like a copy of the program please contact HRAmodeler@valleyair.org.
• District Meteorological Processing Procedures (2 mb)
• Meteorological Data Template – zip file (326 kb)
• NO₂/NO_X In-Stack Ratios
• CAPCOA 1-Hour NO2 Modeling Guidance
• District 1-Hour SO2 Area Designation Modeling Protocol
• DRAFT District PM2.5 Modeling Procedures
• Policy for Modeling Intermittent Operating Units

Modeling Resources

All health risk assessments must comply with the Office of Environmental Health Hazard Assessment’s (OEHHA’s) guidelines. Any methodology that does not use HARP must be reviewed by ARB and/or OEHHA prior to submission to the District to ensure that OEHHA’s guidelines are fully implemented.

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