EPA released Modeled Emission Rates for Precursors guidance

Posted by on Thursday, May 30th, 2019 in Newsletters
What’s Happening Now

TCEQ Trade Fair Recap – Thanks again to everyone who made it to the 2019 Texas Commission on Environmental Quality (TCEQ) Environmental Trade Fair! We hope you found the presentations useful and informative. We also want to give a big shout-out to all the folks who came by the Providence booth on the Exhibit Floor to say "Hi" and visit. It’s always a great pleasure for us, and we look forward to seeing you next year at the 2020 Environmental Trade Fair.

EPA News

2019 R/S/L Presentations – EPA recently posted PDFs of all the presentations from the 2019 Regional/State/Local Modelers’ Workshop. They can be found here.

AERMOD Development Webpage – EPA has created a new webpage on SCRAM called AERMOD Modeling System Development. This webpage will serve the user community as a place where we can keep up with near-term and longer-term enhancements to AERMOD, AERMET, AERMAP, etc. You will also be able to keep up with the various AERMOD white papers. Visit https://www.epa.gov/scram/aermod-modeling-system-development to learn more.

Final MERPs Guidance Released – On April 30, 2019 EPA released Guidance on the Development of Modeled Emission Rates for Precursors (MERPs) as a Tier 1 Demonstration Tool for Ozone and PM2.5 under the PSD Permitting Program. This new document provides technically credible guidance on how to assess the impact of secondary PM2.5 and ozone as part of a Prevention of Significant Deterioration (PSD) permitting exercise. It includes discussion on the use of Modeled Emission Rates for Precursors (MERPs). These MERPs are based on photochemical grid modeling studies conducted by EPA at over 100 locations in the US. The modeling for MERP development looked at (for each location) a low-level source and an elevated source. Each source emitted precursors of ozone (VOC, NOx) and precursors of secondary PM2.5 (SO2, NOx), and the model calculated maximum ozone or secondary PM2.5 based on those rates. Applying the applicable MERP generates a conservative, but technically appropriate method for estimating impacts of secondary PM2.5 and/or ozone. For more information, go to https://www3.epa.gov/ttn/scram/guidance/guide/EPA-454_R-19-003.pdf.

Other Upcoming EPA Guidance – EPA has indicated we can expect to see draft PM2.5 and ozone permit modeling guidance sometime in the summer of 2019.

New AERMOD coming soon! – At the March AWMA modeling conference, EPA revealed that we can expect to see a new version of AERMOD to be released in the summer of 2019. Some changes in the new version will include:

  • A new LOWWIND alpha (experimental) option
  • A new Tier 2 NO2 option (also alpha)
  • A new RLINE line source option (not sure if it will be alpha or beta)
  • Two new building downwash alpha options – PRIME2 and PRIMEORD
  • Bug fixes related to buoyant line source algorithm and AERMET

EPA noted that other AERMOD technical enhancements that are being worked on, but will not be in this 2019 release, include:

  • A new Tier 3 NO2 option (based on ADMS model)
  • Overwater impacts improvements – e.g. lattice structure downwash, shoreline/coastal fumigation
  • Saturated plumes

As soon as this new version of AERMOD is released we will incorporate it into BEEST.

New AERSURFACE – On February 21, 2019, EPA released the new, draft version of AERSURFACE, called 19039_DRFT. This new draft has been released for public review and testing. After the informal comment period, EPA will incorporate the public feedback and release an updated version of AERSURFACE for regulatory applications.

EPA presented a webinar on 19039_DRFT on April 4, 2019. If you missed it, EPA has posted the webinar slides to SCRAM. For more information on 19039_DRFT, go to https://www.epa.gov/scram/draft-aersurface. There, you will find source code, executables, a user’s guide and other documentation.

Upon release of the final, updated version of AERSURFACE, we will incorporate it into BEEST and AERMOD Wizard as soon as possible!

12th Conference on Air Quality Models – EPA has tentatively scheduled the 12th Conference on Air Quality Models for October 1‑3, 2019 in Research Triangle Park, NC. This triennial Clean Air Act-mandated conference will provide the opportunity for public input to EPA’s ongoing model and modeling guidance development. Keep watching SCRAM (www.epa.gov/scram) for updates.

Terrain Data Conversion – As we mentioned in December, EPA has come up with a workaround regarding obtaining land cover data and NED data in GeoTIFF format. See https://www.epa.gov/scram/interim-access-and-process-use-1992-nlcd-and-ned. When BEEST 11.14 comes out, it will include a new tool that will allow you to convert the ArcGrid-formatted data to GeoTIFF in a seamless, painless manner!

Conferences and Workshops

Air & Waste Management Association

**New Source Review Workshop Manual** – If you do New Source Review air permitting (and/or modeling), please note that AWMA’s New Source Review Manual is now available! This new version is available online in an interactive, hyperlinked and searchable format. It covers all the big NSR-related topics, such as PSD / nonattainment applicability, BACT, air quality analysis, and modeling. Check here for details.

**HOT** AWMA ACE 2019 – The 112th AWMA Annual Conference and Exhibition (ACE) will be held in Quebec City, Quebec, Canada June 25‑28, 2019. This year’s theme is "Winds of Change – Environment, Energy, and Health." General conference information can be found at https://www.awma.org/ace2019.

**HOT** AMWA Louisiana Section Annual Conference – The Louisiana Section of AWMA will be holding their annual conference October 16‑17, 2019 at the L’Auberge Casino and Hotel in Baton Rouge, LA. For more on registration, sponsor or exhibitor information, click here.

If your company, organization, agency, State, etc. has an upcoming modeling or air quality-related event and you’d like it publicized in Providence/Oris Notes, please send that information to us at info@providenceoris.com, and we’ll be happy to include it.

Simply the Best!


BEEST 11.13 is out! This new version includes:

  • Ability to Find "Other" objects within Show Current Data Graphically
  • An updated Import KML tool
  • Displays a message when a met station’s profile base elevation is not in the EPA database
  • Several bug fixes

*AND* BEEST 11.13 includes our new Lidar Calculator, a tool that helps you obtain heights for buildings and tanks based on airborne downward-looking Lidar data.

We presented a webinar back on January 29 that presented both the new features found in BEEST 11.13 *plus* a demo of our new Lidar Calculator. Click here to view the video for the webinar.

As we teased above, when BEEST 11.14 comes out, it will include a new tool that will allow you to convert the ARCGrid-formatted land-cover and NED data to GeoTIFF in a seamless, painless manner!

As always, users in maintenance can download the most recent version of BEEST from Support → Software Updates.

"Go BEEST Mode!" — What? You still don’t have your own "Go BEEST Mode" t-shirt? Don’t worry, we’ve got plenty left – so email your request to info@providenceoris.com and receive your very own "Go BEEST Mode" T-shirt! You’ll be the envy of modelers everywhere!

AerScreen for Windows

Since AerScreen for Windows uses both AERMOD and AERMAP, we released AerScreen for Windows 3.06 on May 31, 2018. This new version fully supports AERMOD 18081 and AERMAP 18081.

Users in maintenance can download the most recent version of AerScreen for Windows from Support → Software Updates.

Professional CalPuff

Our most recent version of Professional CalPuff (4.00) was released August 26, 2016 and is available to all registered users with current maintenance.

Users in maintenance can download the most recent version of Professional CalPuff from Support → Software Updates.


AERMOD Wizard 1.00 is already here! We think that this handy tool will be a game changer and so will you! Imagine being able to download ambient monitoring data and creating a temporally-varying (e.g. HROFDY, SEASHR) AERMOD-ready background file with just a few clicks! Or what about being able to do multiple Class I area Q/D analyses with just a few clicks? Or building wind roses and/or pollutant roses and be able to export them to Google Earth – also with just a few clicks? That’s not all this amazing tool can do, so go here to get your own copy of AERMOD Wizard.

AERMOD Wizard 1.01 will be out soon and it will include the ability to do backward, as well as forward, trajectories. These trajectories can be exported to Google Earth.

**Check out this month’s Modeling Tip of the Month to see just how easy it is to speed up creation of ambient background data with AERMOD Wizard!**

*We’re off to see the Wizard!*

If you have suggestions for an enhancement to any of our modeling software products, please let us know and we’ll do our best to incorporate it into the software ASAP!

Modeling Tip of the Month

AERMOD Wizard is the latest utility from Providence/Oris, and it offers you many new tools related to air quality modeling. Over the next few months, we’ll be including AERMOD Wizard-based Modeling Tips of the Month. For this month, we’ll start with ambient background concentrations. When conducting NAAQS modeling, we always have to account for background concentrations of pollutants, whether characterized by explicitly modeling other sources, or by including ambient monitoring data. AERMOD Wizard makes the development of your monitored ambient background data a snap.

Begin by opening AERMOD Wizard. After it opens, you’ll see a map of the USA, with several control buttons to the left of the map. Above the word Display on the left, you’ll see a dropdown arrow that allows you to select one of the six (6) criteria pollutants: carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), PM2.5, PM10, and sulfur dioxide (SO2). Select NO2 for your pollutant. Under the word Display on the left, check the boxes next to Monitors and Names. When you do that, the letter N shows up at the location of every NO2 monitor all across the US, along with their names/IDs. Along the upper part of the control buttons to the left, you’ll find the Zoom In, Zoom Out, and Zoom to Selected Area buttons. Using any of these, you can zero in to your area of interest and find the NO2 station you want to get ambient data from. When you have found it, place your cursor over the N and you will have a yellow pop-up appear. Left-click, and you will see a hatched circle appear over the station, meaning you’ve marked it for download. Go to the Monitors menu bar at the top of the page, left-click and select Download Monitoring Data and the year(s) of data you want and AERMOD Wizard will automatically download that data to your computer and unzip it.

With the data downloaded, you will now see that the N has a box drawn around it. Place your cursor over the N again, and the yellow pop-up reappears and tells you the name of the station, plus which year(s) was downloaded. Right-click and now you have 3 options to choose from: Summarize Monitoring Data, Process Monitoring Data and Show Pollutant Rose. Select Process Monitoring Data and a popup appears, showing which years you want to select for creating your ambient background data. Click Continue and AERMOD Wizard displays tabular statistics of each of the years of data you wish to process. Click Calculate BG Values and you get a display showing the years to be processed plus a prompt for which temporal mode you want to use (e.g. ANNUAL, SEASON, SEASHR, etc.), plus either the rank (1st high, 4th high, etc.) or automatically creating a 98th percentile. Click Calculate and AERMOD Wizard does the work for you by generating your ambient background data and then pops up a nice array of background values that you can either copy/paste into BEEST or write to a generic AERMOD SO type file.

“Our expertise is contagious. Catch it!”

AERMOD Modeling for Permits

**We’re going back on the road!** That’s right, our next scheduled AERMOD Modeling for Permits class for 2019 will be August 20‑21 in Denver, Colorado. Register today and plan to join us in the Mile-High City! Click here to register!

Advanced AERMOD

Similarly, our next scheduled Advanced AERMOD class for 2019 is going to be August 22‑23, also in Denver.

Advanced AERMOD covers those topics that are near and dear to modelers, such as:

  • NAAQS modeling for 1-hour NO2, 1-hour SO2 and 24-hour PM2.5 (including MaxDCont Viewer)
  • Meteorological data processing with AERMET / AERMINUTE / AERSURFACE
  • Changes related to the new Appendix W (Guideline on Air Quality Models)
  • MAXIFILE and ARRAY2 processing
  • AERMOD alpha options, such as PSDCREDIT
  • AERMOD Wizard and its uses

Click here to register!

2019 Class Schedule

Here’s our current list of the rest of our scheduled AERMOD classes for 2019:

Class Dates
AERMOD Modeling for Permits December 3 – 4
Advanced AERMOD December 5 – 6


**Don’t forget, if our schedule of classes doesn’t mesh with your schedule, or if you have several people that need to be trained at once, contact us about setting up an on-site class. Have laptop, will travel!**


**BeestXpress has been upgraded to run AERMOD 18081**

In addition, BeestXpress users have some great system enhancements to work with:

  • The "Job Details" webpage now displays the pollutant being modeled;
  • The "Job Details" webpage now displays run progress for MAXDCONT calculations;
  • Modeling runs with multiple partitions now include a combined AERMOD input file (*.DTA) in the output .ZIP file;
  • Added an option to the "Submit Job" webpage that affects modeling runs with multiple partitions: the intermediate output files created by each partition can be omitted from the output .ZIP file
  • The "Job Search" webpage now includes the option to search by project number
  • Users have access to up to 50 partitions per AERMOD run

To date, BeestXpress has processed over 300,000 AERMOD runs. Wow!

If you’ve never used BeestXpress, or it has been a while since you did, you may want to log on at www.beestxpress.com to take advantage of our AERMOD "force multiplier". That AERMOD run that might have taken a day to run on your desktop computer can finish in an hour or less on BeestXpress. When time is money, BeestXpress is the best modeling return on investment there is!

Meteorological Data Processing Services

Do you need AERMOD-ready or CalPuff-ready meteorological data? If so, we can help! Whether it’s running the AERMET / AERMINUTE system or a full CalMet run, Providence has the background, know-how, and experience to have your data processed and ready for you ASAP. Need on-site data processed? We do that, too! If you’d like more information, contact us at info@providenceoris.com or jamesred@providenceeng.com.

Consulting Solutions

One thing that we’re very proud of is the depth and range of our modeling experience and expertise. The kinds of air quality models we’ve used include all types, ranging from simple screening tools like SCREEN3 and AERSCREEN to plume models like ISC and AERMOD to CalPuff to CAMx. The types of analyses included basic Significant Impact Level, NAAQS, PSD increment consumption, Class I analyses, air toxics, and SIP attainment demonstrations. Most recently, we have begun conducting nonattainment permit inter-pollutant trading (NOx for VOC) modeling using CAMx. So, we’ve seen it all. To that end, should you or your clients need additional modeling assistance or just a second set of eyes to QA or peer review your modeling (ranging from initial protocol up to final submission), we stand ready to help. Feel free to contact us at (512) 258-8855 or info@providenceoris.com.



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June 25-28, 2019
112th AWMA Annual Conference and Exhibition
Quebec City, Quebec, Canada

August 20-21, 2019
AERMOD Modeling for Permits
Denver, CO

August 22-23, 2019
Advanced AERMOD
Denver, CO

October 1-3, 2019
12th Conference on Air Quality Models
Research Triangle Park, NC

October 16-17, 2019
AWMA Louisiana Section Annual Conference
Baton Rouge, LA

Our complete class schedule can be found at www.providenceoris.com.