In last month’s newsletter, we discussed that the U.S. EPA Administrator signed the final rule updating Appendix W to 40 CFR Part 51 – the Guideline on Air Quality Models. This final rule revised the scientific formulation in the AERMOD modeling system.
As described above, the U.S. EPA has been busy this month! Major updates to the Guideline on Air Quality Models and associated changes to the AERMOD Modeling System mean that Lakes Environmental will be very busy in the coming weeks as we update AERMOD View & AERMET View to incorporate the new models.
Late on the evening of September 26, 2024, Hurricane Helene made landfall in Florida’s Big Bend region. A Category 4 storm at the time, the storm caused significant extensive impacts to the southeastern United States with significant impacts in western North Carolina. The National Oceanic and Atmospheric Administration’s (NOAA) National Centers for Environmental Information (NCEI) headquartered in Asheville, NC faced power outages and loss of network connectivity for a period of several weeks following the storms dissipation.
AERMAP is the terrain preprocessor program for incorporating terrain elements into air dispersion modeling analyses conducted using the AERMOD dispersion modeling system. Natively, AERMAP reads two types of terrain data:
In 2010, the United States Environmental Protection Agency (U.S. EPA) revised the National Ambient Air Quality Standards (NAAQS) for short-term nitrogen dioxide (NO2) and sulfur dioxide (SO2). Due to the unique forms of these standards – which are based on annual distributions of daily maximum hourly concentrations as opposed to the distribution of all hourly values – the AERMOD air dispersion model had to be updated to perform calculations accordingly.
One limitation of the CALPUFF air dispersion model is that it can only be executed on a single processor (i.e., serially). Previous modeling tips have discussed ways around this limitation. For example, executing CALPUFF with a single source will run faster than attempting to model multiple sources at a time. Modelers can then employ CALSUM to assess cumulative impacts. This approach has the added benefit of providing a way to assess individual source contributions.