ENVIRON - CAMx - Overview

Overview

Technical Overview

CAMx is an Eulerian photochemical dispersion model that allows for integrated "one-atmosphere" assessments of gaseous and particulate air pollution (ozone, PM2.5, PM10, air toxics) over many scales ranging from sub-urban to continental. It is designed to unify all of the technical features required of "state-of-the-science" air quality models into a single system that is computationally efficient, easy to use, and publicly available. CAMx can be supplied environmental input fields from many meteorological models (e.g., MM5, RAMS, and WRF) and emission inputs developed using many emissions processors (SMOKE, CONCEPT, EPS, EMS).

Version 5.20 offers expanded capabilities over previous versions. Detailed information about all of these features is provided in the CAMx User's Guide.

In addition to the features it shares with most photochemical grid models, some of the most notable features of CAMx are:

Two-way grid nesting
Flexi-Nesting, which allows for reconfiguration of nested grids during a simulation
Multiple gas phase chemistry mechanism options (CB4, CB05, SAPRC99)
Multiple gas phase chemistry solver options (EBI, IEH, LSODE)
Evolving multi-sectional or static two-mode particle size treatments
Plume-in-Grid (PiG) module for sub-grid treatment of selected point sources
Probing Tools:

Ozone and Particulate Source Apportionment Technology (OSAT/PSAT)
Decoupled Direct Method (DDM/HDDM) for source sensitivity of ozone and other species
Process Analysis (PA)
Reactive Tracer (RTRAC/RTCMC) Source Apportionment for air toxics

Mass conservative and consistent transport numerics:

Multiple horizontal advection solvers (PPM, Bott)
Multiple vertical diffusion methods (K-theory, ACM2)

Parallel processing using Open-MP on shared-memory systems
Parallel processing using Message Passing Interface (MPI) on distributed-memory systems

CAMx Applications in the U.S.

Since 1996, CAMx has been employed extensively by local, state, regional, and federal government agencies, academic and research institutions, and private consultants for regulatory assessments and general research throughout the U.S. CAMx has been used in more than 20 countries on nearly every continent.

1-Hour Ozone
- OTAG, NOx SIP Call (eastern U.S.)
- Texas (SIPs for Houston, Dallas-Fort Worth, East Texas)
- El Paso/Juarez trans-border analysis
- LADCO (Great Lakes region)
- Pennsylvania (SIP for Pittsburgh)
8-Hour Ozone

Texas (Houston, Dallas-Ft Worth, San Antonio, Austin, East Texas)
Oklahoma (Oaklahoma City, Tulsa)
Colorado (Denver)
New Mexico
Missouri/Illinois (St. Louis)
LADCO (Great Lakes region)
Florida (Tampa, Orlando, Jacksonville)
Arizona (Phoenix)
Southern California (Los Angeles)
Louisiana (Baton Rouge)
Central California (CCOS)

Local PM

Missouri/Illinois (St. Louis PM2.5 SIP)
Idaho (Boise PM10 SIP)
Southern California (Los Angeles PM10, PM2.5)

Regional Strategies

EPA analysis of Heavy-Duty Diesel Rule(Eastern U.S.)
EPA analysis of Clean Air Interstate Rule (Eastern U.S.)

Regional Haze/U.S. Regional Planning Organizations (RPOs)

Midwest (MRPO)
Western (WRAP)
Central (CENRAP)
Southeast (VISTAS)
Oregon/Washington (Columbia River Gorge)

BART Modeling

Texas BART screening analysis
Arkansas cumulative BART modeling

Oil & Gas Development

BLM Moxa Arch gas infill development project (SW Wyoming)
BLM Hiawatha gas infill development project (Wyoming-Colorado)
BLM Pinedale Anticline (SW Wyoming)
Four Corners Air Quality Task Force (NW New Mexico)

Toxics

Arizona (Phoenix)
Northern California (San Fransico Bay Area)
Michigan (Detroit)
Southern California (Los Angeles MATES-II)
EPA National mobile source toxics rulemaking

Mercury

Wisconsin and Continental U.S.