Alerts
This page was developed to speed the transfer of modeling guidance updates to the North Carolina modeling community.
July 10, 2020
NC PSD Modeling Guidance has been updated to reflect the 2017 revisions to Appendix W. The updated guidance document can be downloaded from the Modeling Page.
September 1, 2019
Meteorological datasets have been updated to reflect 2014-2018. These files should be used for any future modeling.
June 1, 2018
Meteorological datasets have been updated to reflect 2013-2017. These files should be used for any future modeling.
Use AERMOD 18081 for modeling submittals.
Surface Profile Elevations have been updated.
May 31, 2018
UPDATE TO QUARRY MODELING GUIDELINES:
An update to AQAB's Quarry Modeling Guidelines has been made. It is available on our Modeling Page: To download, click here.
NC TOXICS MODELING GUIDANCE UPDATE:
Removed Section 1.2.3 Quarries pertaining to PM10 modeling. Updated Section 5.4 Meteorlogical Data/AERMET to reflect Appendix W requirements for onsite meteorological data.
July 14, 2017
NC Air Toxic Modeling Guidance has been updated and can be found under the Modeling tab
April 11, 2017
Meteorological Datasets have been updated
All meteorological datasets have been updated to reflect the 2012 - 2016 years. These files should be used for any future modeling.
October 21, 2016
Meteorological Datasets have been updated
All meteorological datasets have been updated to reflect the 2011 - 2015 years. These files should be used for any future modeling.
September 29, 2015
Updates to AERMOD and AERMET
An updated version of AERMOD (dated 15181) has now been posted to the SCRAM website and replaced the previous version of AERMOD (dated 14134). A summary of the changes incorporated into version 15181 of AERMOD can be found in Model Change Bulletin #11 (MCB#11). An update to the AERMOD User's Guide Addendum along with a new compliment of Test Cases have also been posted on SCRAM. The link to the updated version of AERMOD is here.
Additionally, an updated version of AERMET (dated 15181) has been posted to the SCRAM website and replaced the previous version of AERMET (dated 14134). A summary of the changes incorporated into version 15181 of AERMET can be found in Model Change Bulletin #6 (MCB#6). The link to the updated version of AERMET is here.
Meteorological Datasets have been updated
All meteorological datasets have been updated to reflect the updated version of AERMET (15181) for the 2010-2014 years and are now available. These files should be used for any future AERMOD modeling.
April 29, 2015
Meteorological Datasets have been updated
All meteorological datasets have been updated to reflect the 2010-2014 years and are now available. These files should be used for any future AERMOD modeling.
April 10, 2014
Updated Meteorological Data Files Available for RDU.
The 2008-2012 met. data files for Raleigh-Durham (RDU) have been updated to include a change in station location along with a change in profile base elevation. These files should be used for any future AERMOD modeling.
May 2, 2013
Meteorological Data Re-Processed to Include IFW Group Info.
The latest available consecutive 5 year met. datasets have been re-processed to accommodate those stations that are part of the Ice-Free Winds (IFW) group. This results in more lower speed winds being captured and fewer "calms" being reported in the data files. Details on the use of the IFWGROUP keyword in AERMINUTE processing can be found in Sect. 3.1.2 of the AERMINUTE User's Guide.
The minimum wind speed threshold of 0.5 m/s was retained as recommended by EPA in their March 8, 2013 memorandum.
The revised 5-year meteorological datasets can be downloaded from our website here.
The locations and elevations of several ASOS stations have been verified and some changes to the Profile Base Elevations file have been made. The latest file can be obtained here.
March 11, 2013
Latest Meteorological Data Processed for 0.5 m/s Wind Threshold
The latest available consecutive 5 year met. datasets have been re-processed to accommodate the minimum wind threshold of 0.5 m/s as recommended by EPA in their March 8, 2013 memorandum that can be found here.
The revised data can be downloaded from our website here.
February 14, 2013
Updated Meteorological Data Now Available!
The latest available consecutive 5 year met. datasets is now available for download. The updated data, processed using AERMET ver. 12345, includes an expanded list of stations to select from, and covers the years 2008 through 2012 (with the exception of a couple of stations). The expanded dataset includes a much more extensive coverage area in NC and the data can be used for both Toxics and PSD modeling. Go here to access the data.
December 18, 2012
Updates to AERMOD and AERMET
An updated version of AERMOD (dated 12345) has now been posted to the SCRAM website and replaced the previous version of AERMOD (dated 12060). A summary of the changes incorporated into version 12345 of AERMOD can be found in Model Change Bulletin #8 (MCB#8). An update to the AERMOD User's Guide Addendum along with a new compliment of Test Cases have also be post on SCRAM. The respective link to the updated version of AERMOD is here.
Additionally, an updated version of AERMET (dated 12345) has been posted to the SCRAM website and replaced the previous version of AERMET (dated 11059). A summary of the changes incorporated into version 12345 of AERMET can be found in Model Change Bulletin #3 (MCB#3). An update to the AERMET User's Guide Addendum along with a new compliment of Test Cases have also be post on SCRAM. The respective link to the updated version of AERMET is here.
October 9, 2012
NCDAQ Screen Modeling Policy
Effective immediately, the preferred screening model for NCDAQ is AERSCREEN. As of January 2, 2013, SCREEN3 will not be accepted. In the interim time, SCREEN3 may be accepted if specifically approved by NCDAQ/AQAB. All NCDAQ/AQAB guidance documents will be updated as soon as possible to reflect this status.
April 8, 2011
Updated PSD Modeling Guidance
A new version of the NCDAQ PSD Modeling Guidance, which makes some small corrections, has been loaded on this website. To view the document, click here.
December 21, 2010
Updated Protocol Checklist
The North Carolina Modeling Protocol Checklist has been revised and now includes a requirement to identify the facility ID, where applicable, (previous update) and to identify the coordinate system used in the refined modeling analysis. Please be advised that if the new checklist is not submitted, you will receive a request to do so before the modeling is reviewed.
December 21, 2010
Updated Protocol Checklist
The North Carolina Modeling Protocol Checklist has been revised and now includes a requirement to identify the facility ID, where applicable, (previous update) and to identify the coordinate system used in the refined modeling analysis. Please be advised that if the new checklist is not submitted, you will receive a request to do so before the modeling is reviewed.
September 28, 2010
Updated PSD Modeling Guidance
A new version of the NCDAQ PSD Modeling Guidance has been loaded on this website. To view the document, click here.
September 23, 2010
New Coastal Area Met Set for AERMOD
AQAB has created a new processed meteorological dataset for AERMOD use. The surface data are from Beaufort, and the upper air data are from Newport (dates = 2005 to 2009). See our updated guidance for instruction on where to use this new data.
August 9, 2010
Interim PM2.5 SIL Established
Until EPA develops and promulgates the 24-hr and annual SILs for PM2.5, NCDAQ has adopted interim PM2.5 SILs of 1.2 ug/m3 (24-hr) and 0.3 ug/m3 (annual). The interim SILs represent the third option currently being proposed by EPA and were derived by adjusting the PM10 SILs as a proportion of the NAAQS ratio of PM2.5 to PM10.
July 23, 2010
Interim SO2 1-hr SIL Established
Until EPA develops and promulgates a 1-hr SO2 SIL for the recently promulgated SO2 1-hr NAAQS, NCDAQ has adopted an interim 1-hr SO2 SIL of 10 ug/m3. The 10 ug/m3 SIL was derived using the same procedures developed by the Northeast States for Coordinated Air Use Management (NESCAUM) for the 1-hr NO2 SIL (also adopted by DAQ - see alert for Interim NO2 1-hr SIL) and is based on the ratio of the existing 1-hr CO SIL to the 1-hr CO NAAQS.
May 27, 2010
Interim NO2 1-hr SIL Established
Until EPA develops and promulgates a 1-hr NO2 SIL for the recently promulgated NO2 1-hr NAAQS, NCDAQ has adopted an interim 1-hr NO2 SIL of 10 ug/m3. The 10 ug/m3 SIL was developed by the Northeast States for Coordinated Air Use Management (NESCAUM) and is based on the ratio of the existing 1-hr CO SIL to the 1-hr CO NAAQS.
March 23, 2010
NCDAQ Screening Meteorology in AERMOD is Rescinded
Effective immediately the option of using the NCDAQ screening meteorology in AERMOD is rescinded. This primarily affects modeling in the Western portion of NC. Our modeling guidance will be updated soon to reflect this policy. To view our updated Western NC modeling guidance, click here.
December 22, 2009
Updated Toxics Modeling Guidance
An updated version of the "Guidelines for Evaluating The Air Quality Impacts of Toxic Pollutants in North Carolina" is posted on this website. All previous versions are obsolete. You can review the new guidelines by clicking here.
September 21, 2009
NCDAQ PSD Modeling Requirements
Effective immediately, the NCDAQ PSD modeling requirements will include an evaluation and, as applicable, modeling of "primary PM2.5" (filterable and condensable) emissions. Modeling for PM2.5 will be required whenever the PSD PM10 Significant Emission Rates (SERs) are exceeded. Modeling for PM2.5 may also be required, pursuant to 15A NCAC 2D .0501, whenever an increase in PM2.5 emissions is expected even if the PM10 SERs are not exceeded; this requirement will be evaluated on a case-by-case basis and will be discussed during the PSD Pre-application meeting. Click here for guidance for conducting PM2.5 modeling.
June 18, 2009
AQAB Policy on USGS NED Data
For AERMOD applications, AQAB prefers use of the USGS elevation data from the National Elevation Database (NED). The old DEMs for NC have a number of documented problems that are corrected in the NED data.
June 11, 2009
Update Protocol Checklist and D3 Form
The AQAB Protocol Checklist and the D3 Form have been updated to require facility IDs and to incorporate new guidance on terrain modeling recommendations. To download, click (Protocol Checklist and D3 Form).
July 8, 2008
PSD Guidance Update
Updates / Corrections to Section 5.
June 19, 2008
AERMOD Met Policy Update
All AERMOD submissions must use the processed meteorology that is currently available on the DAQ/AQAB website. Earlier versions will not be accepted. The AQAB routinely reviews the meteorological data used to ensure the appropriate data has been selected.
June 5, 2008
Processed AERMOD met data updated.
Asheville and Raleigh met data updated.
May 1, 2008
Western NC Modeling Guidance Posted
The NCDAQ/AQAB has posted guidance for modeling in Western North Carolina to provide strategies for the mountainous region. To download, click here.
May 1, 2008
NC PSD Guidance Updated
The NCDAQ/AQAB has updated the North Carolina PSD modeling guidance. To download, click here.
April 3, 2008
Processed AERMOD met data updated.
Go to our meteorological data page to download the data set you need. Use of these data sets is required in NC, unless AQAB approves otherwise on a case-by-case basis.
November 5, 2007
NC PSD Guidance Published
The NCDAQ/AQAB has developed modeling guidance to assist the PSD permit applicant to identify and comply with the modeling requirements associated with the PSD permitting process. This guidance will be routinely updated to incorporate new or revised PSD modeling requirements/methodologies and as such, we encourage the user to periodically check the AQAB web site for the latest guidance and download, as necessary. We also encourage user feedback for suggested guidance changes or additions. To download, click here.
September 13, 2007
Update to Toxics Modeling Guidelines
To download, click here.
February 23, 2007
Processed AERMOD met data available.
Go to our meteorological data page to download the data set you need. Use of these data sets are required in NC, unless AQAB approves otherwise on a case-by-case basis.
February 1, 2007
Update to Toxics Modeling Guidelines
To download, click here.
February 1, 2007
Update to Protocol Checklist
To download, click here.
January 22, 2007
New TSP Modeling Policy
Effectively immediately, TSP (PM 0-100 microns) will be evaluated consistent with that of a NC air toxic. The TSP air quality analysis will use modeled receptors beginning at the facility property line and will exclude background TSP concentrations and offsite source impacts. In addition, modeled receptors along public right-of-ways traversing the facility property will not be required. DAQ will continue to accept the preliminary impact analysis approach to determine if a full impact TSP analysis will be required.
September 20, 2006
UPDATE TO QUARRY MODELING GUIDELINES:
An update to AQAB's Quarry Modeling Guidelines has been made. It is available on our Modeling Page: To download, click here.
May 30, 2006
QUARRY MODELING UPDATE:
Effective immediately, TSP background concentrations will no longer be required to be added to the modeled TSP impacts from quarry operations. The quarry impacts will be compared directly to the TSP NCAQS. The AQAB Quarry Modeling Guidance has been updated to reflect this policy.
April 11, 2006
TRANSPORTATION FACILITY GUIDLINES:
An updated version of the Transportation Facility Guidelines has been posted on this website.
November 9, 2005
AERMOD IMPLEMENTATION STRATEGY:
Effective November 9, 2005, AERMOD is the DAQ-preferred model for most refined modeling applications, replacing ISCST3, and will be the primary model used by DAQ to evaluate facility compliance or perform modeling as a part of any DAQ special modeling study.
During the one-year AERMOD implementation period ending November 9, 2006, permit applicants will be encouraged to use AERMOD; however, ISCST3 may be used at the user's discretion. After that date, AERMOD will be required for appropriate regulatory compliance modeling applications. ISCST3 use will be limited and must be pre-approved by DAQ.