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Ozone Modeling

 

Summary

To aid in evaluating the impact of emissions control strategies as well as developing Attainment Demonstrations in accordance with State Implementation Plan (SIP) requirements, the RAQC engages in photochemical modeling efforts. Photochemical modeling is a grid-based computer model used to simulate air pollution episodes. It is the most effective tool for determining how serious air pollution problems are and how they occur. Photochemical modeling allows for the assessment of:

    • How sensitive pollutants are to varying parameters such as meteorological conditions and emission rates
    • How sensitive pollutants are to control scenarios
    • Efficacy of proposed control strategies

Photochemical modeling is completed using EPA approved modeling platforms and methodologies. A detailed modeling protocol is developed which outlines the technical details of the modeling being performed. The protocol documents the approach, procedures, participants and other requirements need to conduct photochemical grid model modeling. This page provides references, tools, and reports that have been developed to support the RAQC’s ongoing modeling efforts.

Modeling Reports and Dashboards for 2026 Serious 70 ppb SIP Planning Efforts

The RAQC is conducting modeling efforts to aid in planning and SIP development efforts under the 2015 8-hour ozone Standards. Below are currently available reports and tools developed in support of this effort.

Draft Modeling Protocol – Denver Metro/North Front Range 2025 Serious State Implementation Plan for the 2015 Ozone NAAQS (May 8, 2024).  This document is open for initial review and comment until June 21, 2024.  Subsequent versions will address comments submitted.  Please send comments to Tom Moore (tmoore@raqc.org).

RAQC Modeling and Analysis Forum (April 2024)

 

Complete 2022 Oil&Natural Gas Annual Emissions Inventory Report (ONGAEIR) database (March 2024)

 

CSC Ozone Modeling and Analysis Plan Report Presentation, January 2024

2024-25 Serious 70 ppb SIP Modeling & Analysis Platform (MAP) Plan for the Denver Metro / North Front Range Ozone Nonattainment Area -December 2023

IWDW Denver Ozone Precursor WEP-AOI Potential Contribution Analysis Method – December 2023

Denver Metropolitan/North Front Range Nonattainment Area Emission Inventory Review, November 30, 2023

Potential Improvements to the Oil and Gas Emission Inventory for the Denver Metro/North Front Range Nonattainment Area, November 3, 2023

 

Modeling Reports and Dashboards for 2024 Severe 75 ppb SIP Planning Efforts

The RAQC is conducting modeling efforts to aid in planning and SIP development efforts under the 2008 8-hour ozone Standards. Below are currently available reports and tools developed in support of this effort.

IWDW Denver Ozone Precursor WEP-AOI Potential Contribution Analysis Method – December 2023

Air Quality Technical Support Document for the Denver Metro / North Front Range 2008 NAAQS Severe Ozone SIP (Ramboll – September 2023)

2026 Attainment Year Modeling Demonstration for the Denver Metro / North Front Range Ozone Nonattainment Area – Severe SIP (Ramboll – September 2023)

2016 Base Year – Model Performance Evaluation for the Denver Metro / North Front Range Ozone Nonattainment Area – Severe SIP (Ramboll – September 2023)

Denver Metro / North Front Range Nonattainment Area Oil & Gas Emission Inventory Final Report – for 2008 NAAQS Severe SIP modeling (Ramboll – July 2023)

Modeling Protocol Addendum for 2008 and 2015 Ozone Standards (Ramboll – June 2023)

Presentation of Draft SIP Elements – Attainment Demonstration (RAQC – May 2022)

Modeling Protocol for 2008 and 2015 Ozone Standards (Ramboll – May 2022)

Preliminary 2026 Future Year Modeling Results (RAQC – March 2022)

Modeling Protocol for 2008 and 2015 Ozone Standards  (Ramboll – April 2019)

2023 Emissions Dashboard (Ramboll/Alpine – April 2021)

2023 NOx/VOC Sensitivity Analysis – Daily (Ramboll/Alpine – April 2021)

2023 NOx/VOC Sensitivity Analysis – Hourly (Ramboll/Alpine – April 2021)

2023 Local Source Apportionment Analysis (Ramboll/Alpine – April 2021)

2023 Transport Analysis (Ramboll/Alpine – April 2021)

Archived Reports and Presentations from Previous Planning Efforts

Reports and tools developed in support of prior modeling efforts are detailed below:

NOx/VOC Sensitivity Analysis (Ramboll/Alpine Geophysics – March 2018)

Source Apportionment Modeling Report (Ramboll – April 2017)

2017 Photochemical Grid Modeling – Model Performance Evaluation (Ramboll – September 2017)

2017 Photochemical Grid Modeling – Attainment Demonstration (Ramboll – September 2016)

Source Apportionment Modeling Analysis for the Denver Early Action Ozone Compact (Environ/Alpine Geophysics, May 2004)

Modeling Forums

Forums are dedicated RAQC meetings where modeling methodologies, analyses, and results are discussed in-depth. They cover a wide range of topics, from how the model is selected to how the model demonstrates the effects of local, regional, and international sources on ozone. Below are references to forums previously conducted by the RAQC.

April 23, 2024 Forum

Topics Covered:

  • Draft Conceptual Model of Ozone Formation in the DM/NFR Non-attainment Area
  • Emissions Inventory Improvements and Controls Presentation
  • SIP Modeling Protocol

 

October 26,2023 Forum

Topics Covered:

  • Severe 75 ppb and Moderate 70 ppb SIP modeling – Results and Lessons Learned
  • Emissions, Control Strategy, and Modeling Plans for the Serious 70 ppb SIP planning effort during 2024-25

 

May 12, 2023 Forum

Topics Covered:

  • Methodology Outline: Denver Metro/North Front Range Oil and Gas Emission Inventory, May 10, 2023
  • Revised Oil and Gas Emission Inventory Results
      • 2017 Oil and Gas Emission Inventory Spreadsheets, April 28,2023
      • 2026 Oil and Gas Emission Inventory Spreadsheets, May 10, 2023
  • Severe SIP Modeling Plan

 

May 18, 2022 Forum

Topics Covered:

    • 2016 Modeling Platform Update since April 2021
    • Analysis of 2020 and 2021 Meteorology
    • 2023 and 2026 Design Value Projections
    • Planned and Potential Sensitivity Analyses

 

April 14, 2021 Forum 

Topics Covered:

    • 2016 Modeling Platform Update
    • 2023 NOx/VOC Sensitivity Analysis
    • 2023 Local Source Modeling
    • 2023 International and Interstate Transport Analysis

 

June 4, 2020 Forum

Topics Covered:

    • Development of 2016 Base Case Modeling,
    • 2020 and 2023 Future Year Modeling Projections

 

November 2, 2017 Forum

Topics Covered:

    • Overview of Modeling Sensitivities
    • 2017 Local Source Apportionment Modeling
    • Contribution of International Emissions on 2011 Base Case
    • 2023 Ozone Projections and NOx/VOC Sensitivity
    • FRAPPE and DISCOVER-AQ 2014 Regional Source Impacts
    • Comparison of Oil and Gas Inventories with Monitored Ambient VOC Precursors

 

August 9, 2012 Forum

Topics Covered:

    • Development of 2008 Base Case Model
    • Ozone Model Evaluation for the Denver 2008 Episode
Guidance Documents

Guidance documents from the EPA recommend steps to conduct modeling for ozone nonattainment areas. Generally, the guidance comes in two parts. The first part includes how to set up and apply a photochemical modeling platform, which includes meteorology, emissions, and air quality modeling. The second part describes how to use the modeling platform to project future year concentrations and demonstrate whether attainment of the standard is likely.

Modeling Guidance – Final (Nov. 2018) 

Requests for Proposals

The RAQC puts out requests for services from a consulting firm to aid in completing the modeling recommended under EPA guidance.

2024 Request for Proposal

2018 Request for Proposal

2011 Request for Proposal (RFP)