You are here:
PREPARING MPAS FOR GLOBAL RETROSPECTIVE AIR QUALITY MODELING: AN EVALUATION OF A 2016 SIMULATION WITH COMPARISONS TO WRF
Citation:
Gilliam, R., J. Herwehe, R. Bullock, Jon Pleim, AND David-C Wong. PREPARING MPAS FOR GLOBAL RETROSPECTIVE AIR QUALITY MODELING: AN EVALUATION OF A 2016 SIMULATION WITH COMPARISONS TO WRF. 2018 CMAS Conference, Chapel Hill, North Carolina, October 22 - 24, 2018.
Impact/Purpose:
Development and demonstration of an advanced and sophisticated meteorological model (MPAS) for use in global to regional air quality modeling. This specific product is an evaluation of MPAS for a full year with comparisons to the current meteorological model WRF that is used for regulatory air quality modeling. The research demonstrates that MPAS compares very well to WRF and certainly sufficient to drive a next generation global air quality model.
Description:
The US EPA has a plan to leverage recent advances in meteorological modeling to develop a "Next-Generation" air quality modeling system that will allow consistent modeling of issues from global to local scale. The meteorological model of choice is the Model for Prediction Across Scales-Atmosphere (MPAS-A) that has been developed by the National Center for Atmospheric Research in recent years. While CMAQ developers have been working on a method to couple CMAQ components to MPAS-A for full global chemical transport modeling, a team of weather modelers has been preparing MPAS-A for accurate meteorological simulations. This includes four dimensional data assimilation that allows for long simulations of past weather with no growth in error. We have also added the Pleim-Xiu land-surface model (P-X LSM), Asymmetric Convective Model 2 (ACM2) and Pleim surface layer, which are key components in the current meteorological model WRF. The evaluation of MPAS-A and comparison to WRF includes a full annual 2016 simulation using both a 92-25 km and 46-12 km global mesh with finer meshes centered over the CONUS. Evaluation includes comparisons of the model runs to surface meteorology, PRISM precipitation, radiation and upper air rawindsonde measurements. MPAS-A generally compares well with WRF for most of 2016. Error levels in surface meteorology are at or below WRF levels during the cooler parts of the year and slightly worse during the summer. Precipitation totals are generally less than WRF and monthly PRISM estimates during the cooler half of the year, but more mixed differences during the warm season. Patterns of precipitation (spatial correlation), however, are well replicated. Solar radiation in MPAS-A is higher than WRF and measurements, indicating a lack of clouds in MPAS-A versus WRF. Finally, a comparison of 92-25 km and 46-12 km meshes shows clear improvements in surface meteorology as grid scale is reduced. The comparisons indicate the meteorology of MPAS-A is sufficient for retrospective global air quality modeling.