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Recent advancement of EPA’s global air quality modeling system: MPAS-CMAQ
Citation:
Willison, J., Jon Pleim, D. Wong, R. Gilliam, R. Bullock, J. Herwehe, C. Hogrefe, G. Pouliot, G. Sarwar, AND R. Mathur. Recent advancement of EPA’s global air quality modeling system: MPAS-CMAQ. 103rd American Meteorological Society Annual Meeting, Denver, CO, January 08 - 12, 2023.
Impact/Purpose:
We have coupled the National Center for Atmospheric Research (NCAR) Model for Prediction Across Scales – Atmosphere (MPAS-A) with the Community Multiscale Air Quality (CMAQ) model developed at the USEPA. This new tool enables a new capability: simultaneous modeling of air quality across global, regional, and local scales. In this presentation, we will describe the value and design of the MPAS-CMAQ system and present results from recent simulations. The system performs reasonably well when compared with similar models and observations.
Description:
We have coupled the National Center for Atmospheric Research (NCAR) Model for Prediction Across Scales – Atmosphere (MPAS-A) with the Community Multiscale Air Quality (CMAQ) model developed at the USEPA. This new tool enables modeling of air quality from global to regional to local scales. In this presentation, we will describe the value and design of the MPAS-CMAQ system and present results from recent simulations. The EPA-modified version of MPAS-A provides meteorological forcing and horizontal transport for CMAQ. Modifications to MPAS include the addition of four-dimensional data assimilation (FDDA), the ACM2 PBL model, and the PX land surface model. Anthropogenic emissions follow the approach used in EPA’s Air QUAlity TimE Series Project (EQUATES). Biogenic emissions are provided by inline Model of Emissions of Gases and Aerosol from Nature (MEGANv3.1). Global ozone fields from the ECMWF’s Copernicus Atmosphere Monitoring Service (CAMS) are used for initialization and for stratospheric ozone data assimilation in the upper layers of the model for the entire simulation periods. We will show results from a multi-year simulation on a uniform mesh with 120 km cell spacing and from sub-seasonal simulations using a variable resolution mesh (60-12 km) with refinement over North America. Air quality evaluation includes comparisons with World Ozone and Ultraviolet Radiation Data Centre (WOUDC) ozonesondes and surface-based measurement networks. In addition, we contextualize our results with comparisons to atmospheric compositions simulated by alternative tools such as WRF-CMAQ with hemispheric coverage, the GEOS Composition Forecasting (GEOS-CF) system, and the Copernicus Atmospheric Monitoring Service (CAMS) global reanalysis.