Performance Differences of the National Air Quality Forecasting Capability When There is a Major Upgrade in the Chemistry Modules

Abstract

There have been large advancement in modeling science and chemical constituent measurement of air pollutants harmful to the public health. The National Oceanic and Atmospheric Administration (NOAA) National Air Quality Forecasting Capability (NAQFC) is a vital service that NOAA provides to the general public to help safeguarding the public health as well as the environmental resilience through announcement of information-driver mitigation and adaptation action. NAQFC is poised to upgrade from using the Community Multiscale Air Quality Model (CMAQ) version 5.0.2 to version 5.2. This is noticeable a multiple sub-version number leaping forward corresponding to major upgrades in chemistry and emission sciences. The following lists the major science upgrade: (a) upgrade gas chemistry for the Carbon-Bond Mechanism version 5 (CB05) to version 5 Revision1 (CB05R1); (b) Inclusion of Halogen chemistry; (c) Employed more explicit speciation for isoprene and monoterpenes from biogenic sources; (d) Upgraded the aerosol module using a more sophisticated secondary aerosol production suite of multi-generational oxidation mechanism; and (e) Application of a fuller set of National Emission Inventory (NEI) from base year 2014. We tested the new system for a summer case retrospectively and compared its forecast performance with the real-time operational NAQFC. The U.S. Environmental Protection Agency (EPA) AIRNow monitoring network was used to verify the forecast accuracy. We noticed considerable discrepancies in the performance of the two realization of forecasting simulations.