Introduction to AIRPACT
What is AIRPACT
What is AIRPACT?
Pollutant emissions are another first order determinate of air quality, along with meteorology, and are calculated referring to detailed spatial databases of land use, traffic volumes, industrial emissions and natural emissions from vegetation and soils, all adjusted as appropriate by date, time of day and predicted temperature and solar (uv) light intensity. AIRPACT's project name, the Air Information Report for Public Access and Community Tracking, reflects the goal of bringing meaningful information on the quality of the air (or the level of air pollutants) to the public from a variety of sources, including both model results and monitoring stations.
What is air quality
What is Air Quality?
and the primary particulates of concern:
What should I look at
What should I look at?
AIRPACT results are presented on a daily basis under date-named folders, shown in a 'latest on top' order. A daily forecast result is shown as columns of links for Meteorology, Emissions, CMAQ results, and Statistics. Regionally, the critical pollutants are found as O3 (ozone) and PM2.5 under the CMAQ results column. Emissions, CMAQ results and statistics links are also organized into 'gas phase' and 'particulate' groups. Most of the links (except for the elevation and land-use links under Meteorology and the Statistics) run animations, with the user given control via widgets in the left hand frame. Times are given on the images for the hour of the result and the time stamp in the upper frame indicates both the UTZ and interpreted time. Time stamps are for the model's instantaneous emissions rate or mixing ratio; the results are not hourly averages.
Links to explore in the AIRPACT simulation data table (shown here for the current simulation):
How does it work
How does it work?
AIRPACT uses an EPA developed model called the Community Model for Air Quality (CMAQ) that calculates air quality for a region by treating the region as a three-dimensional grid of cells of regular size. Thus, AIRPACT treats the Northwest region as a gridded volume of 95 cells by 95 cells, in 21 vertical layers. The cells are 12 km in N-S and E-W extents but the vertical level depth varies with elevation. The problem of predicting the region's air quality thus becomes the problem of computing the air quality for a volume of air contained within a model grid cell volume, many times over. For each grid cell volume, air quality is solved by calculating changes in air chemistry from the beginning of a time step (say t=0) until the end of that step (t=1) accounting for the contribution of several different factors for each chemical and particulate of concern:
Who is involved
Who is involved?
Federal, state, local and tribal AQ authorities jointly strive to protect human health and other values by protecting air quality; AIRPACT has been developed with support, guidance and cooperation from US EPA Region 10, the WA Department of Ecology, the Oregon Department of Environmental Quality and the Idaho Department of Environmental Quality, and the Puget Sound Clean Air Agency, among others.
For more information, contact: