DOI: 10.5281/zenodo.15732713
title: CMAQ v5.5 Annual 2023 Gridded Predictions Across the US and Canada

description: CMAQ v5.5 Annual 2023 Gridded Predictions Across the US and Canada

Data contact: Havala Pye, ORCID: 0000-0002-2014-2140

This dataset provides daily predictions of ozone and fine particle (PM2.5) species across the contiguous U.S. and a large fraction of Canada at 12km horizontal resolution for 2023. Values are predicted by CMAQv5.5 (https://doi.org/10.5281/zenodo.13883210) with CRACMM chemistry.

Data contents:HR2DAY_LST_ACONC_2023_12US4_v2_2023.nc: gridded CMAQ model output for 2023SpecDef_Conc_cracmm2_v2.txt: Species definition file used to define total PM2.5 and other PM2.5 species at the "combine" stepREADME.txt: README file describing dataGRIDCRO2D.12US4.35L.230101: GRIDCRO2D file output from MCIP that describes the CMAQ+WRF simulation grid 

2023 Simulation: - Performed by Havala Pye ORD/CEMM/AESMD- AMET database: amad_CRACMM; label: 2023_12US4_20250213cmaq55plusv2- Description: CMAQv5.5+ public version downloaded 2/13/2025. (SHA: 783dc11668a83b9ec243c2cf7d20471ecd34dfae). Last Merge on 5.5 plus: Jan 31. Chemical mechanism: CRACMM2. Dry deposition: STAGE with Emerson et al. 2020 aerosol parameters. Vertical diffusion: acm. Windblown dust emissions: on. Sea spray emissions: on. Lightning NOx: on. Land surface model: PX. Bidirectional ammonia exchange: on. Fertilizer NH3 emissions: computed in-line. HONO production on ground surfaces: on. Gravitational settling of aerosols: on. Scale free trop O3 to potential vorticity: off. Biogenic emissions: BEIS in-line. Aerosol optics: approx of Mie Theory for internally homogeneous particle. WRF v4.6.0. BCON: GEOSCF mapped to cracmm2. Solver: EBI. Compiler: Intel 23.2. OMI file set to use 2019 data. Entire month of December 2022 (using representative days) discarded as spinup. HAP emissions are from explicit emission factors rather than VOC speciation.  Species definitions file for post processing concentrations updated 2/27/2025. Simulations and post-processing performed by Havala Pye. CMAQv5.5 postprocessing was corrected to include 4 previously missing SOA species (AISO4J + AISO5J + AHONITJ + ATRPNJ).- Original file locations: /work/MOD3DEV/has/2023cracmm_ages/runs/20250213cmaq55plus/data/POST/HR2DAY_LST_ACONC_2023_12US4_v2_2023.nc; /work/MOD3DATA/2023_12US4/met/GRIDCRO2D.12US4.35L.230101

Variables in the HR2DAY file (netcdf format):O3_MDA8: maximum daily 8-hour average ozone in ppb by volumeO3_DAILYAV: daily-average ozone in ppb by volumeO3_MAX: maximum hourly ozone by day in ppb by volumePM25_TOT_AVG: daily-average PM2.5 total mass in micrograms per cubic meter of airPM25_SO4_AVG: daily-average sulfate total mass (PM2.5 size) in micrograms per cubic meter of airPM25_NO3_AVG: daily-average nitrate total mass (PM2.5 size) in micrograms per cubic meter of airPM25_NH4_AVG: daily-average ammonium total mass (PM2.5 size) in micrograms per cubic meter of airPM25_OC_AVG: daily-average organic carbon total mass (PM2.5 size) in micrograms (carbon) per cubic meter of airPM25_EC_AVG: daily-average elemental carbon total mass (PM2.5 size) in micrograms (carbon) per cubic meter of air

Variables in the GRIDCRO2D file (netcdf format, see Otte and Pleim (2010) for documentation on the file):LAT: grid cell center latitude in degrees NLON: grid cell center longitude in degrees EMSFX2: map-scale factor squared in m2/m2HT: terrain elevation in mDLUSE: dominant land use category (no units)LWMASK: land-water mask (1=land) (no units)PURB: urban percent of cell based on land in percent

General performance comments:- Ozone is generally overestimated on average in the eastern US in summer. Peaks (high episodes and events) are generally underestimated.- Ozone is generally underestimated in the western US in summer (excluding coastal area which can be high).- Winter PM2.5 is generally higher in the model than observations (likely due to residential wood combustion overestimates).- Summer PM2.5 is generally lower in the model than observations (may be due to a combination of low SOA and/or wildfire emissions).

The HR2DAY concentration file was created by the HR2DAY program distributed with CMAQ (https://github.com/USEPA/CMAQ/tree/main/POST/hr2day) using "combine" (https://github.com/USEPA/CMAQ/tree/main/POST/combine) output as input to HR2DAY. Total PM25 at the "combine" step is defined in terms of raw model species in SpecDef_Conc_cracmm2_v2.txt and _AVG is appended to names at the HR2DAY step. Note that the PM25_OC_AVG and PM25_EC_AVG unit labels embedded in the netcdf file indicate "ug/m3" but these species are always "ugC/m3" consistent with the species names. The description of CRACMM2 model species is at https://github.com/USEPA/CRACMM/blob/main/metadata/cracmm2/cracmm2_metadata.csv. 

Please cite the following for CMAQ with CRACMM2:Skipper, T. N., D'Ambro, E. L., Wiser, F. C., McNeill, V. F., Schwantes, R. H., Henderson, B. H., Piletic, I. R., Baublitz, C. B., Bash, J. O., Whitehill, A. R., Valin, L. C., Mouat, A. P., Kaiser, J., Wolfe, G. M., St. Clair, J. M., Hanisco, T. F., Fried, A., Place, B. K., and Pye, H. O. T.: Role of chemical production and depositional losses on formaldehyde in the Community Regional Atmospheric Chemistry Multiphase Mechanism (CRACMM), Atmos. Chem. Phys., 24, 12903–12924, https://doi.org/10.5194/acp-24-12903-2024, 2024.

More information on GRIDCRO2D is available in:Otte, T. L. and Pleim, J. E.: The Meteorology-Chemistry Interface Processor (MCIP) for the CMAQ modeling system: updates through MCIPv3.4.1, Geosci. Model Dev., 3, 243–256, https://doi.org/10.5194/gmd-3-243-2010, 2010.

For transparency in data documentation, please also cite the doi associated with this data (doi: 10.23719/1532366 or doi: 10.5281/zenodo.15732714).

DISCLAIMER: This data product has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for public release. At the time of release, the data had not yet been published in peer-reviewed literature. The data is provided for research and the user should verify the data is suitable for their intended use.