Photochemical Grid Modeling

The U.S. Environmental Protection Agency (EPA) widely recognizes and routinely utilizes Photochemical Grid Modeling (PGM) for regulatory analysis and attainment demonstrations. PGM simulates the impacts from single and multi-source studies by estimating pollutant concentrations and deposition for chemically reactive pollutants over large spatial scales. Similar regional scale modeling can be performed for inert pollutants as well. Trinity provides comprehensive modeling for both PGM and regional air quality studies by offering such modeling services to our clients nationally and internationally. For more than 10 years, experts at Trinity have been supporting clients with the following PGM and regional scale modeling services.

  • Photochemical grid modeling: Comprehensive Air Quality Model with extensions (CAMx) and Community Multiscale Air Quality (CMAQ) modeling system
  • Emissions processing: Emission Preprocessing System, version 3 (EPS3), Motor Vehicle Emission Simulator (MOVES), Sparse Matrix Operator Kernel Emissions (SMOKE), and Model of Emissions of Gases and Aerosols from Nature (MEGAN)
  • Meteorological data processing: Weather Research & Forecast (WRF) and 5th Generation Mesoscale Model (MM5)
  • Post Processing and data visualization: Modeled Attainment Test Software (MATS), Visualization Environment for Rich Data Interpretation (VERDI), and ArcGIS
  • Data analysis: Statistical data analysis, Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), wind rose, and pollution rose

Key Application Areas

Trinity has utilized PGM in key application areas including, but not limited to, the following:

  • Single source impact evaluations for Prevention of Significant Deterioration (PSD)  and Federal Energy Regulatory Commission (FERC) permitting
  • Visibility Studies for Regional Haze Best Available Retrofit Technology (BART) and Reasonable Progress (RP) analyses and control strategy evaluations
  • State Implementation Plan (SIP) modeling and planning support
    • Speciated Model Attainment Test (SMAT)
    • Unmonitored Area Analysis (UMAA)
    • Motor Vehicle Emissions Budget (MVEB)
    • Reasonable Further Progress (RFP)
  • Control measure evaluations
    • Precursor contribution and sensitivity demonstrations
    • Reasonably Available Control Technologies and Measures (RACT/RACM)
    • Best Available Control Technologies and Measures (BACT/BACM)
    • Most Stringent Measures (MSM)
  • Source apportionment analyses including Ozone Source Apportionment Technology (OSAT) and Particulate Source Apportionment Technology (PSAT) studies
  • Sensitivity analyses using brute force and Decoupled Direct Method (DDM)
  • Conceptual ozone model
  • Site selection and fatal flaw analyses
  • Inter-Pollutant (IP)/Inter-Basin (IB) credit demonstrations

High Performance Computing Solutions

Trinity has high performance computing (HPC) clusters that are run using state-of-the-art processors supported by high speed networks and high performance storage. The HPC's computational nodes utilize Intel processors with Linux operating environment. Trinity's HPC clusters can simultaneously run several scenarios of resource intensive PGM that has saved an incalculable number of computer processing hours, enabling more in-depth analyses and faster project completion. Trinity periodically upgrades the clusters to maintain the speed and efficiency in meeting clients needs.

Why Choose Trinity

Our experience is multi-faceted and extensive.  Our strategies are innovative, time saving, and cost-effective.  Our staff and tools are the second to none, embodying our company's principle in every way to provide environmental solutions delivered uncommonly well.