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Linking gas, particulate, and toxic endpoints to air emissions in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) (NOAA 2023)
Citation:
Pye, H. Linking gas, particulate, and toxic endpoints to air emissions in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) (NOAA 2023). NOAA Chemical Sciences Laboratory (NOAA CSL) Visit, Boulder, CO, September 19 - 22, 2023.
Impact/Purpose:
This talk will be presented in the NOAA CSL seminar series to disseminate recent work on the CRACMM project as well as foster collaboration on mechanism development. CRACMM is a new mechanism being built for use in CMAQ and other models and will be the official default version in CMAQ in 2026. A more robust CRACMM will better serve EPA and other federal and state agency needs for air quality predictions in applications such as state implementation plans, EPA's AirToxScreen, and the CDC PHASE project. This talk will cover two recent applications of CRACMM within CMAQ: (1) understanding drivers of the PM2.5 vs temperature relationship and (2) representations of wildfire chemistry and emissions. Improving the PM2.5-temperature relationship will build confidence in use of CRACMM in predicting air quality under changes in climate such as in the National Climate Assessment. Applying CRACMM to the FIREX-AQ wildfire campaign will build confidence in predictions of hazardous air pollutants and PM2.5 from fires in CRACMM.
Description:
Chemical mechanisms are at the core of chemical transport models used to understand drivers of air quality and predict concentrations of pollutants in present day and future conditions. Mechanisms are traditionally focused on prediction of the criteria pollutant, ozone, and mass is often duplicated for purposes of predicting other endpoints such as the secondary organic aerosol (SOA) component of fine particle mass. In this work, Dr. Pye will present the recently developed Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM) to show that coupling gas-phase radical chemistry and SOA formation can have benefits for representing the full range of atmospheric reactive organic carbon (ROC). These benefits include expanded coverage of ROC emissions, improved conservation of mass, and new SOA precursors not included in earlier generation mechanisms. This talk will also highlight recent applications of CRACMM in the Community Multiscale Air Quality (CMAQ) modeling system to understand ambient conditions such as those during the Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field campaign.