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2021 Regional Haze SIP Modeling (2016 Episode)

Air quality modeling files and data to support the 2021 Regional Haze State Implementation Plan (SIP) revision.

The United States Environmental Protection Agency's 1999 Regional Haze Rule , updated in 2017 , requires state, tribal, and federal agencies to work together to improve visibility in 156 national parks and wilderness areas (Class I areas) . To comply with the rule, Texas must submit a SIP revision to the EPA. The SIP revision must demonstrate that the state’s emissions do not negatively impact the ability of any Class I area to achieve "natural conditions" by 2064. See below for TCEQ's photochemical modeling results that support the latest SIP revision, 2021 Regional Haze SIP revision.

If you have any questions regarding these files, please email us at with "2021 Regional Haze Modeling Files" in the subject line.

Model Configuration

Meteorological Model: WRF v3.8.1

Photochemical Model: CAMx v6.5ss (Ramboll's unofficial release with several bug fixes from v6.50) with CB6 r4h (CB6 Release 4 and halogen chemistry). CAMx source code was compiled with PGI compiler v18.10 (with -Kieee option), MPICH v3.3.1, and NetCDF on a server running Red Hat Enterprise Linux (RHEL) 7.4; the model runs were conducted on a High Performance Computing Cluster running RHEL 7.7 (4 MPI nodes and 20 OMP threads on each node). Download: CAMx v6.5ss source code TAR-GZIP archive.

Modeling Episode: Jan. 1 - Dec. 31, 2016 (CAMx ramp-up days: Dec. 15 - 31, 2015)

CAMx Modeling

CAMx 2016 base case run name: bc16.v1LN_v1a.2016_wrf381_p2KFsn_i2KFsn

CAMx 2028 future case run name: fy28.v1LN_v1.2016_wrf381_p2KFsn_i2KFsn

Modeling Performance Evaluation and 2064 Glidepath Analysis: ZIP archive of Excel files provided by Ramboll

Modeling Data Files

Due to their large size, most Regional Haze SIP modeling data are not available online. If you would like the data, please email us at with "2021 Regional Haze Modeling Files - Data Request" in the subject line and also specify which set you are requesting: EI, CAMx, WRF, or all.

Pre-CAMx emissions inventory data: File List (total data size is 1.6 TB). Part of emissions inventory data are also available for anonymous-download from the TCEQ Air Modeling FTP site (, /EI/2016_episodes/).

CAMx input and output data: File List (total data size is 6.8 TB). 2016 base case and 2028 future case CAMx output data are also available for anonymous-download from the TCEQ Air Modeling FTP site (, /RH/camx/2016/).

WRF input and output data: File List (total data size is 25 TB)


2021 Regional Haze SIP Revision

Regional Haze Modeling to Evaluate Progress in Improving Visibility in and near Texas - Contract report by Ramboll which assisted TCEQ in setting up CAMx simulations, evaluating model performance, and assessing visibility impairment for a Regional Haze SIP. (June 2020)

Regional Haze Modeling - Contract report by Ramboll which developed the initial CAMx 2016 modeling and provided a preliminary assessment of performance based on Regional Haze Rule requirements. (August 2019)