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www.cppwind.comwww.cppwind.com
Highlights from the 2016 Guideline
on Air Quality Models Conference
Rocky Mountain States S...
www.cppwind.comwww.cppwind.com
Outline
• Updates on AERMOD modeling system
• Building Downwash
• Prognostic meteorological...
www.cppwind.comwww.cppwind.com
Background
• Revisions to Appendix W were proposed by
EPA on July 29, 2015
• Public comment...
www.cppwind.comwww.cppwind.com
AERMOD Updates
EPA has proposed that the following options be incorporated
into the regulat...
www.cppwind.comwww.cppwind.com
AERMET/AERMOD ADJ_U*
• The Beta ADJ_U* option in AERMET associated
with the Bulk Richardson...
www.cppwind.comwww.cppwind.com
AERMET/AERMOD ADJ_U*
• Friction velocity (u*) computed by
AERMET.
• u* used to calculate mi...
www.cppwind.comwww.cppwind.com
AERMOD-Low Wind Options
AERMOD v15181 includes a new LOWWIND3 (LW3) non-DFAULT/BETA
option:...
www.cppwind.comwww.cppwind.com
Capped and Horizontal Stacks
Draft/BETA options for capped & horizontal stacks have been
in...
www.cppwind.comwww.cppwind.com
NOx to NO2 Conversion
• EPA has proposed that the ARM2 and
PVMRM2 options be incorporated a...
www.cppwind.comwww.cppwind.com
Buoyant Line Sources
• Beginning with v15181, AERMOD includes an option to model
buoyant li...
www.cppwind.comwww.cppwind.com
Mobile Source Modeling
• Proposal includes replacement of CALINE3,
CAL3QHC, and CAL3QHCR wi...
www.cppwind.comwww.cppwind.com
Model Clearinghouse Activity
• On use of ARM2
– July 16, 2015; Region 2
– December 22, 2015...
www.cppwind.comwww.cppwind.com
Use of Beta Options
• Clarification on the Approval Process for
Regulatory Application of t...
www.cppwind.comwww.cppwind.com
Building Downwash
• Priority for EPA’s OAQPS and ORD
• Upcoming clearinghouse memo from Reg...
www.cppwind.comwww.cppwind.com
PRIME
AERMOD’s Building Downwash Algorithm
• Used EPA wind tunnel data
base and past litera...
www.cppwind.comwww.cppwind.com
BPIP Diagnostic Tool
http://bit.do/cppwind-BPIPDiagnostic
Likely Overprediction Factor for ...
www.cppwind.comwww.cppwind.com
ComplianceCompliance
CPP’s EBDCPP’s EBD
BPIP Diagnostic
ToolBuilding Geometry
Meteorologica...
www.cppwind.comwww.cppwind.com
Summary of Needed Updates to
PRIMEFlaws that may cause overpredictions:
1. Building wake gr...
www.cppwind.comwww.cppwind.com
AERMOD/PPRIME
Overestimates
Downwash
Reality
Summary of Needed Updates to
PRIME
www.cppwind.comwww.cppwind.com
Refinery Structures Upwind
Solid BPIP Structure Upwind
No Structures
Streamlines for Lattic...
www.cppwind.comwww.cppwind.com
PRIME2 Advisory Committee
Subcommittee of the Atmospheric Modeling and
Meteorology Committe...
www.cppwind.comwww.cppwind.com
PRIME2 Advisory Committee
– EPA mentioned that building downwash is a
priority
– Had about ...
www.cppwind.comwww.cppwind.com
Meteorological Data
• Prognostic meteorological data
– No representative NWS station and in...
www.cppwind.comwww.cppwind.com
Ozone and PM2.5 Formation
Included in Chapter 5 of proposed
Appendix W as a tiered approach...
www.cppwind.comwww.cppwind.com
Ozone and PM2.5 Formation
• Tier 2 relates to using models
to assess impacts from single
so...
www.cppwind.comwww.cppwind.com
Single Source Impacts
• Source impact estimation approaches
– Brute force approach
– Decoup...
www.cppwind.comwww.cppwind.com
Source Impact Estimation
Approaches
Baker, K. Estimating Ozone and Secondary PM2.5 for Perm...
www.cppwind.comwww.cppwind.com
Long Range Transport
• EPA proposing that Appendix W no longer contain
language requiring u...
www.cppwind.comwww.cppwind.com
IWAQM Update
• Interagency Workgroup on AQ Modeling
• FLAG Guidance is being updated
• Curr...
www.cppwind.comwww.cppwind.com
What's Coming?
The good
• Some beta options in AERMOD are
expected to become default
– Hori...
www.cppwind.comwww.cppwind.com
What's Coming?
Ozone and PM2.5 formation
• Uncertainty
– For Tier 1 and Tier 2 ozone and PM...
www.cppwind.comwww.cppwind.com
Sergio A. Guerra, PhD
sguerra@cppwind.com
Mobile: + 612 584 9595
CPP, Inc.
2400 Midpoint Dr...
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Highlights from the 2016 Guideline on Air Quality Models Conference

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The revision of the Guideline on AQ Models (Appendix W) will prompt many changes in the way dispersion modeling is conducted for regulatory purposes. Some of the changes to the Guideline include enhancements and bug fixes to the AERMOD modeling system, new screening techniques to address ozone and secondary PM2.5, delisting CALPUFF as the preferred long-range transport model, and updates on the use of meteorological input data. These changes will have a significant impact on the regulated community. In anticipation of these updates, the Air & Waste Management Association will hold its 6th Specialty Conference: “Guideline on Air Quality Models: The New Path” to provide a technical forum to discuss the Guideline. This talk covered the main highlights from this conference including the presentations from EPA on the status and future direction of the Guideline. Learn how these changes may impact dispersion modeling evaluations for short and long range transport.

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Highlights from the 2016 Guideline on Air Quality Models Conference

  1. 1. www.cppwind.comwww.cppwind.com Highlights from the 2016 Guideline on Air Quality Models Conference Rocky Mountain States Section of the Air & Waste Management Association - Denver, CO April 21, 2016 Sergio A. Guerra, Ph.D. – CPP Inc.
  2. 2. www.cppwind.comwww.cppwind.com Outline • Updates on AERMOD modeling system • Building Downwash • Prognostic meteorological data • Ozone and Secondary PM2.5 • Long Range Transport • What’s next?
  3. 3. www.cppwind.comwww.cppwind.com Background • Revisions to Appendix W were proposed by EPA on July 29, 2015 • Public comment closed on October 27, 2015 • Final rulemaking by July 7 or 8th of 2016 • References: – 11th Modeling Conference Presentations https://www3.epa.gov/ttn/scram/11thmodconfpres.htm – Guideline on AQ Models: The New Path, 6th Specialty Conference https://www3.epa.gov/ttn/scram/11thmodconfpres.htm
  4. 4. www.cppwind.comwww.cppwind.com AERMOD Updates EPA has proposed that the following options be incorporated into the regulatory versions of AERMOD and AERMET: • The ADJ_U* option in AERMET; • The LOWWIND3 option in AERMOD; • The BUOYLINE option in AERMOD for modeling buoyant line sources; and • The POINTCAP and POINTHOR source type options in AERMOD to model capped and horizontal stacks. • NOx-NO2 conversion – ARM2 – PVMRM2
  5. 5. www.cppwind.comwww.cppwind.com AERMET/AERMOD ADJ_U* • The Beta ADJ_U* option in AERMET associated with the Bulk Richardson Number (BULKRN) option has been modified to include a more refined method for calculating THSTAR and extending its applicability for very stable/low wind conditions, based on Luhar and Raynor (BLM, v132, 2009); • The updated ADJ_U* option with BULKRN also includes modifications to subroutine TGINIT in AERMOD to calculate THSTAR; • EPA has proposed that the ADJ_U* option (with or without BULKRN) be incorporated into the regulatory version of AERMET.
  6. 6. www.cppwind.comwww.cppwind.com AERMET/AERMOD ADJ_U* • Friction velocity (u*) computed by AERMET. • u* used to calculate mixing height, initial horizontal and vertical dispersion (sigma-y and sigma-z) • EPA noted in 2007 issues with high concentrations due to treatment of light winds. • AERMOD users started to identify highest impacts associated with low wind speeds (i.e., <1 m/s) during night hours.
  7. 7. www.cppwind.comwww.cppwind.com AERMOD-Low Wind Options AERMOD v15181 includes a new LOWWIND3 (LW3) non-DFAULT/BETA option: • LOWWIND3 increases minimum value of sigma-v from 0.2 to 0.3 m/s, consistent with the LOWWIND2 option, but eliminates upwind dispersion, consistent with the LOWWIND1 option; • The LOWWIND3 option uses an “effective” sigma-y value that replicates the centerline concentration accounting for meander, but sets concentrations to zero (0) for receptors more than 6*sigma-y off the plume centerline, similar to the FASTALL option; • EPA has proposed in that the LOWWIND3 option be incorporated into regulatory version, while the LOWWIND1 and LOWWIND2 options are still available for testing & evaluation purposes.
  8. 8. www.cppwind.comwww.cppwind.com Capped and Horizontal Stacks Draft/BETA options for capped & horizontal stacks have been incorporated in AERMOD (beginning with v06341): • Source types POINTCAP & POINTHOR used to trigger BETA options; • User inputs actual stack exit velocity (Vs) and stack diameter (Ds); • The Model Clearinghouse procedure is used for non-downwash sources; • For the POINTHOR option with downwash the exit velocity is assigned as the initial horizontal velocity of the plume; • For the POINTCAP option with downwash, the initial plume radius is assigned as 2*Ds to account for initial plume spread from the cap, and the initial horizontal velocity of the plume is assigned as the initial exit velocity specified by the user divided by 4 to account for suppressed momentum and buoyancy.
  9. 9. www.cppwind.comwww.cppwind.com NOx to NO2 Conversion • EPA has proposed that the ARM2 and PVMRM2 options be incorporated as regulatory options. http://www.atmos.washington.edu/~lbaylon/research.html
  10. 10. www.cppwind.comwww.cppwind.com Buoyant Line Sources • Beginning with v15181, AERMOD includes an option to model buoyant line sources, using the BUOYLINE source type; • The BUOYLINE option in AERMOD model allows for modeling of buoyant line sources using meteorological data processed through the AERMET meteorological processor; • The BUOYLINE option in AERMOD also allows use of the processing options to support the form of the 1-hr NO2, 1-hr SO2 and 24-hr PM2.5 NAAQS.
  11. 11. www.cppwind.comwww.cppwind.com Mobile Source Modeling • Proposal includes replacement of CALINE3, CAL3QHC, and CAL3QHCR with AERMOD as the Appendix A preferred dispersion model for all mobile source modeling of inert pollutants • Technical Support Document (TSD) for Replacement of CALINE3 with AERMOD for Transportation Related Air Quality Analyses, EPA Document EPA-454/B-15-002 http://www.epa.gov/ttn/scram/11thmodconf/CAL3_A ERMOD_Replacement_TSD.pdf
  12. 12. www.cppwind.comwww.cppwind.com Model Clearinghouse Activity • On use of ARM2 – July 16, 2015; Region 2 – December 22, 2015; Region 4 • On use of Adj-u* beta option and POINTHOR&POINTCAP – February 10, 2016; Region 10 • Upcoming concurrence – Definition of minimum ambient ratio in ARM2; Region 6 – Use of Adj-u* for tall stack in complex terrain; Region1 – Use of wind tunnel derived building dimensions; Region 4 – Informal memo on use of Adj-u* and LOWWWIND3 options
  13. 13. www.cppwind.comwww.cppwind.com Use of Beta Options • Clarification on the Approval Process for Regulatory Application of the AERMOD Modeling System Beta Options • https://www3.epa.gov/ttn/scram/guidance/clarification/AERMOD_Beta_Options_Memo-20151210.pdf
  14. 14. www.cppwind.comwww.cppwind.com Building Downwash • Priority for EPA’s OAQPS and ORD • Upcoming clearinghouse memo from Region 4 • PRIME2 Advisory Committee
  15. 15. www.cppwind.comwww.cppwind.com PRIME AERMOD’s Building Downwash Algorithm • Used EPA wind tunnel data base and past literature • Developed analytical equations for cavity height, reattachment, streamline angle, wind speed and turbulence • Developed for specific building dimensions • When buildings outside of these dimensions, theory falls apart
  16. 16. www.cppwind.comwww.cppwind.com BPIP Diagnostic Tool http://bit.do/cppwind-BPIPDiagnostic Likely Overprediction Factor for each Flow Vector Source 1
  17. 17. www.cppwind.comwww.cppwind.com ComplianceCompliance CPP’s EBDCPP’s EBD BPIP Diagnostic ToolBuilding Geometry Meteorological Data Terrain Data AERMET AERMAP Operating Parameters AERMOD OtherInputs Building Inputs BPIP Diagnostic Tool
  18. 18. www.cppwind.comwww.cppwind.com Summary of Needed Updates to PRIMEFlaws that may cause overpredictions: 1. Building wake growth starts at wrong location – leads overestimated wake height and building downwash zone. 2. Start of building downwash occurs at the wrong location – leads to overstated downwash. 3. Height of building downwash zone (high turbulence) is overestimated. 4. Reduced velocity calculation in wake needs improvement – leads to incorrect plume rise calculation. 5. Streamlines for porous structures should be horizontal and wake velocity and turbulence parameterization is not correct. 6. Streamlines and wakes velocity/turbulence parameterization incorrect for streamlined structures. 7. Transition back to ambient turbulence is questionable. More information is available in papers and presentations #34 and #25 (Petersen and Guerra, 2016)
  19. 19. www.cppwind.comwww.cppwind.com AERMOD/PPRIME Overestimates Downwash Reality Summary of Needed Updates to PRIME
  20. 20. www.cppwind.comwww.cppwind.com Refinery Structures Upwind Solid BPIP Structure Upwind No Structures Streamlines for Lattice Structures
  21. 21. www.cppwind.comwww.cppwind.com PRIME2 Advisory Committee Subcommittee of the Atmospheric Modeling and Meteorology Committee (APM) of the Technical Council of the Air and Waste Management Association (AWMA). The two purposes of this committee include to: 1. Provide a technical review forum to improve the PRIME building downwash algorithms 2. Establish a mechanism to review, approve and implement new science into the model for this and future model improvements
  22. 22. www.cppwind.comwww.cppwind.com PRIME2 Advisory Committee – EPA mentioned that building downwash is a priority – Had about 40-50 people attend the initial meeting – Got an update from ORD about some of their work related to building downwash – EPA is looking into publishing a technical paper soon – EPA’s ORD will be collaborating with this committee
  23. 23. www.cppwind.comwww.cppwind.com Meteorological Data • Prognostic meteorological data – No representative NWS station and infeasible to collect site-specific data – No fewer than 3-years of data – Mesoscale Model Interface Program (MMIF) developed to read prognostic data (i.e., WRF) to create data for input into AERMET and AERMOD, as well as other dispersion models • Draft guidance and evaluation of MMIF available https://www3.epa.gov/ttn/scram/11thmodconf/Draft_MMIF_Guidance.pdf
  24. 24. www.cppwind.comwww.cppwind.com Ozone and PM2.5 Formation Included in Chapter 5 of proposed Appendix W as a tiered approach: • First Tier: – Use of existing technical information such as previous photochemical modeling – Model Emission Rates for Precursors (MERPs) is a Tier 1 tool – MERPS will not replace SERs – Guidance will be forthcoming
  25. 25. www.cppwind.comwww.cppwind.com Ozone and PM2.5 Formation • Tier 2 relates to using models to assess impacts from single sources on ozone and PM2.5 formation – Use of chemical models is recommended including: • Eulerian (e.g., CAMx, CMAQ) • Lagrangian (e.g., CALPUFF, SCICHEM)
  26. 26. www.cppwind.comwww.cppwind.com Single Source Impacts • Source impact estimation approaches – Brute force approach – Decoupled direct method (DDM) sensitivity – Source apportionment
  27. 27. www.cppwind.comwww.cppwind.com Source Impact Estimation Approaches Baker, K. Estimating Ozone and Secondary PM2.5 for Permit Related Programs, A&WMA’s 6th Specialty Conference - Chapel Hill, NC, April 12, 2006
  28. 28. www.cppwind.comwww.cppwind.com Long Range Transport • EPA proposing that Appendix W no longer contain language requiring use of CALPUFF or other Lagrangian model for LRT assessments. • For NAAQS demonstrations: Near-field modeling is sufficient to address whether a source will cause of contribute to a NAAQS violation so EPA does not consider a LRT assessment beyond 50 km necessary for inert pollutants. • EPA recognizes that LRT assessments may be necessary in limited situations for PSD increment and proposes a screening approach where CALPUFF or other appropriate model/tool may be used.
  29. 29. www.cppwind.comwww.cppwind.com IWAQM Update • Interagency Workgroup on AQ Modeling • FLAG Guidance is being updated • Current guidance tied to Appendix W • Plan is to have it be a stand alone document • CALPUFF will likely continue to be used for the next 3-5 years • MMIF documentation will be emphasized
  30. 30. www.cppwind.comwww.cppwind.com What's Coming? The good • Some beta options in AERMOD are expected to become default – Horizontal/capped stack – Adjusted surface roughness in AERMET – LOWWIND3 option – ARM2 and PVMRM2 for NOx to NO2 conversion
  31. 31. www.cppwind.comwww.cppwind.com What's Coming? Ozone and PM2.5 formation • Uncertainty – For Tier 1 and Tier 2 ozone and PM2.5 evaluations – Long Range Transport • More time and expense • Analyses more vulnerable to legal challenge
  32. 32. www.cppwind.comwww.cppwind.com Sergio A. Guerra, PhD sguerra@cppwind.com Mobile: + 612 584 9595 CPP, Inc. 2400 Midpoint Drive, Suite 190 Fort Collins, CO 80525 + 970 221 3371 www.cppwind.com @CPPWindExperts Thanks!

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