George Mason University North American Chemical Reanalysis (NACR)

This dataset contains the George Mason University North American Chemical Reanalysis (NACR) data and simulation outputs, specifically for 2002-2021 trends in land, meteorology, emissions, and nitrogen deposition.  

NACR is based on a state-of-the-science offline-coupled weather and chemical transport modelling system driven by detailed inventories of anthropogenic and natural source emissions (See Methods for more details).  The meteorological simulations are downscaled from the European Centre for Medium-Range Weather Forecasts’ (ECMWF) Reanalysis Version 5 (ERA5) (https://www.ecmwf.int/en/forecasts/dataset/ecmwf-reanalysis-v5)  using the Weather Research and Forecasting (WRF) model, which drives process-level simulations of the full life cycle of major air pollutants and their precursors using the U.S. EPA Community Scale Air Quality (CMAQ) model.  Phase I of NACR used in this study includes the simulation period of 2002-2021 with a 12x12km horizontal resolution WRF/CMAQ modeling domain centered over the contiguous U.S. (CONUS).  

Critical to the results in this work is the use of a reliable and coherent long-term emissions dataset that includes both detailed anthropogenic and fire emissions over CONUS. The NACR simulations here the US EPA’s Air QUAlity TimE Series (EQUATES) project for years 2002-2017 combined with U.S. EPA National Emissions Inventories (NEI) and related emissions modeling platforms for years 2018-2021.  The use of EQUATES and NEI emissions in the full chemistry NACR simulations allow for quantifying the contribution of fires, particularly wildfires in the western U.S. and their impacts on long-term trends of climate and weather, nitrogen deposition, and resulting critical load implications for terrestrial ecosystems in the U.S.  These results and NACR data can thus be further used to assess potential implications for specific ecosystem, agricultural, and economic damages resulting from continued climate change and related increases in fire activity and emissions.  

The included tarballs contain the following post-processed, gridded (12x12km) NACR data:

Grid/domain and landuse data:  NACR_2002-2021_grid_landuse.tar

Land and meteorological output:  NACR_2002-2021_land_meteorology.tar

Emissions data and modeling output:  NACR_2002-2021_emissions.tar

Chemical deposition outputs:  NACR_2002-2021_chem_dep.tar