January and July monthly average ACONC files for the CMAQv5.1 TUCL and RetroPhot sensitivity runs that were performed and presented in the manuscript. This dataset is associated with the following publication: Appel, W., S. Napelenok, K. Foley, H. Pye, C. Hogrefe, D. Luecken, J. Bash, S. Roselle, J. Pleim, H. Foroutan, B. Hutzell, G. Pouliot, G. Sarwar, K. Fahey, B. Gantt, D. Kang, R. Mathur, D. Schwede, T. Spero, D. Wong, J. Young, and N. Heath. Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1. Geoscientific Model Development. Copernicus Publications, Katlenburg-Lindau, GERMANY, 10: 1703-1732, (2017).

ACONC files containing simulated ozone and PM2.5 fields that were used to create the model difference plots shown in the journal article. This dataset is associated with the following publication: Appel, W., S. Napelenok, K. Foley, H. Pye, C. Hogrefe, D. Luecken, J. Bash, S. Roselle, J. Pleim, H. Foroutan, B. Hutzell, G. Pouliot, G. Sarwar, K. Fahey, B. Gantt, D. Kang, R. Mathur, D. Schwede, T. Spero, D. Wong, J. Young, and N. Heath. Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1. Geoscientific Model Development. Copernicus Publications, Katlenburg-Lindau, GERMANY, 10: 1703-1732, (2017).

CMAQv5.1 Base NEIv2 AQS Hourly site compare output containing paired model/ob values that were used for some of the plots in the manuscript. This dataset is associated with the following publication: Appel, W., S. Napelenok, K. Foley, H. Pye, C. Hogrefe, D. Luecken, J. Bash, S. Roselle, J. Pleim, H. Foroutan, B. Hutzell, G. Pouliot, G. Sarwar, K. Fahey, B. Gantt, D. Kang, R. Mathur, D. Schwede, T. Spero, D. Wong, J. Young, and N. Heath. Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1. Geoscientific Model Development. Copernicus Publications, Katlenburg-Lindau, GERMANY, 10: 1703-1732, (2017).

CMAQv5.1 Base NEIv1 AQS hourly sitex files containing hourly paired model/ob data for the AQS network. This dataset is associated with the following publication: Appel, W., S. Napelenok, K. Foley, H. Pye, C. Hogrefe, D. Luecken, J. Bash, S. Roselle, J. Pleim, H. Foroutan, B. Hutzell, G. Pouliot, G. Sarwar, K. Fahey, B. Gantt, D. Kang, R. Mathur, D. Schwede, T. Spero, D. Wong, J. Young, and N. Heath. Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1. Geoscientific Model Development. Copernicus Publications, Katlenburg-Lindau, GERMANY, 10: 1703-1732, (2017).

Files containing daily maximum 8-hr ozone mixing ratio observations and WRF/CMAQ simulations that were contributed by EPA/ORD/NERL/CED researchers to the manuscript “On the Limit to the Accuracy of Regional Air Quality Models”. This dataset is associated with the following publication: Rao, S.T., H. Luo, M. Astitha, C. Hogrefe, V. Cover, and R. Mathur. On the limit to the accuracy of regional-scale air quality models. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 20(3): 1627–1639, (2020).

Software Model simulations were conducted using WRF version 3.8.1 (available at https://github.com/NCAR/WRFV3) and CMAQ version 5.2.1 (available at https://github.com/USEPA/CMAQ). The meteorological and concentration fields created using these models are too large to archive on ScienceHub, approximately 1 TB, and are archived on EPA’s high performance computing archival system (ASM) at /asm/MOD3APP/pcc/02.NOAH.v.CLM.v.PX/. Figures Figures 1 – 6 and Figure 8: Created using the NCAR Command Language (NCL) scripts (https://www.ncl.ucar.edu/get_started.shtml). NCLD code can be downloaded from the NCAR website (https://www.ncl.ucar.edu/Download/) at no cost. The data used for these figures are archived on EPA’s ASM system and are available upon request. Figures 7, 8b-c, 8e-f, 8h-i, and 9 were created using the AMET utility developed by U.S. EPA/ORD. AMET can be freely downloaded and used at https://github.com/USEPA/AMET. The modeled data paired in space and time provided in this archive can be used to recreate these figures. The data contained in the compressed zip files are organized in comma delimited files with descriptive headers or space delimited files that match tabular data in the manuscript. The data dictionary provides additional information about the files and their contents. This dataset is associated with the following publication: Campbell, P., J. Bash, and T. Spero. Updates to the Noah Land Surface Model in WRF‐CMAQ to Improve Simulated Meteorology, Air Quality, and Deposition. Journal of Advances in Modeling Earth Systems. John Wiley & Sons, Inc., Hoboken, NJ, USA, 11(1): 231-256, (2019).

Monthly site compare scripts and output used to generate the model/ob plots and statistics in the manuscript. The AQS hourly site compare output files are not included as they were too large to store on ScienceHub. The files contain paired model/ob values for the various air quality networks. This dataset is associated with the following publication: Appel, W., S. Napelenok, K. Foley, H. Pye, C. Hogrefe, D. Luecken, J. Bash, S. Roselle, J. Pleim, H. Foroutan, B. Hutzell, G. Pouliot, G. Sarwar, K. Fahey, B. Gantt, D. Kang, R. Mathur, D. Schwede, T. Spero, D. Wong, J. Young, and N. Heath. Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1. Geoscientific Model Development. Copernicus Publications, Katlenburg-Lindau, GERMANY, 10: 1703-1732, (2017).

This dataset contains the data contributed by EPA/ORD/NERL/CED researchers to the manuscript "Advanced Error Diagnostics of the CMAQ and CHIMERE modeling systems within the AQMEII3 Model Evaluation Framework" led by Dr. Efisio Solazzo of the European Commission's Joint Research Center. This dataset is associated with the following publication: Solazzo, E., C. Hogrefe, A. Colette, M. Garcia-Vivanco, and S. Galmarini. Advanced error diagnostics of the CMAQ and Chimere modelling systems within the AQMEII3 model evaluation framework. Atmospheric Chemistry and Physics. Copernicus Publications, Katlenburg-Lindau, GERMANY, 17: 10435-10465, (2017).

Annual CMAQ model output for 2016 for approximately six different simulations. This dataset is not publicly accessible because: Data are too large to upload to ScienceHub. It can be accessed through the following means: These data can be requested from the author. Format: Data formats include I/O API and csv. This dataset is associated with the following publication: Appel, K.W., J. Bash, K. Fahey, K. Foley, R. Gilliam, C. Hogrefe, B. Hutzell, D. Kang, R. Mathur, B. Murphy, S. Napelenok, C. Nolte, J. Pleim, G. Pouliot, H. Pye, G. Sarwar, D. Schwede, F. Sidi, T. Spero, D. Wong, L. Ran, and S. Roselle. The Community Multiscale Air Quality (CMAQ) Model Version 5.3: System Updates and Evaluation. Geoscientific Model Development. Copernicus Publications, Katlenburg-Lindau, GERMANY, 14: 2867-2897, (2021).