Air quality simulations for Southeast Texas (SETx) were conducted with the Comprehensive Air Quality Model with Extensions (CAMx) version 7.20 (1). The SETx air quality modeling platform is based on modifications to the most recent CAMx platform developed by the Texas Commission on Environmental Quality (TCEQ) to support the State Implementation Plan (SIP) for ozone (2). The SETx platform includes explicit simulation of hazardous air pollutants (HAPs). Meteorological fields from the Weather Research and Forecasting Model (WRF) version 4.1.5 (3) are representative of a seven-month time period spanning April 1 - October 31, 2019. Point, nonpoint, onroad, and nonroad emissions are from the U.S. Environmental Protection Agency's (EPA) 2020 National Emissions Inventory (NEI) (4) with biomass burning emissions estimates for 2019 from the TCEQ (2).
The horizontal domain configuration of the SETx platform described in Table 1 includes an outer domain with 4-km x 4-km grid cell resolution spanning the Neches River Basin and an inner domain with 1-km x 1-km grid cell resolution over Jefferson, Orange, and southern Hardin Counties. The domains are defined on the Lambert Conformal Conic map projection in accordance with the parameters shown below, which are consistent with TCEQ modeling domains (2):
- First True Latitude (Alpha):
33°N
- Second True Latitude (Beta):
45°N
- Central Longitude (Gamma):
97°W
- Projection Origin:
(97°W, 40°N)
- Spheroid:
Perfect Sphere, Radius = 6370 km
Table 1. Horizontal grid structure and parameters for the SETx-UIFL CAMx domains.
+-----------------------+---------------------------+---------- ------------+--------------------+
| Domain Name | Range (km) | Number of Cells | Cell Size (km) |
| (Abbreviation) | Easting Northing | Easting Northing | Northing Easting |
+-----------------------+---------------------------+-----------------------+--------------------+
| Texas-Louisiana 4-km | | | |
! (uifl_4km) | (108,432) (-1224,-828) | 81 89 | 4 4 |
| Southeast Texas 1-km | | | |
| (uifl_1km) | (252,324) (-1152,-1080) | 72 72 | 1 1 |
+-----------------------+---------------------------+-----------------------+--------------------+
The vertical grid structure includes 20 layers to an average of 2,144 m above ground level. The surface (first) vertical layer has a height of 34 meters (m).
Simulations were conducted for nine HAPs including acetonitrile, 1,3-butadiene, benzene, ethylbenzene, ethylene oxide, hexane, styrene, toluene, xylenes (mixed isomers). Results are available in the form of 5th, 25th, 50th (median), 75th, 95th, 98th, 99th, and 100th (maximum) percentile concentrations in units of parts per billion by volume (ppb), determined from hourly average concentrations provided by CAMx across the seven-month time period. The GeoTIFF files include results for each surface grid cell within the 4-km and 1-km domains.
References
- https://www.camx.com/download/source/
- https://www.tceq.texas.gov/airquality/airmod/data/tx2019)
- https://github.com/wrf-model/WRF/releases
- https://www.epa.gov/air-emissions-inventories/2020-national-emissions-inventory-nei-data
The data is provided as a single zip file, with subdirectory of domain name followed by HAP abbreviation.
./uifl_4km/benz
./uifl_4km/nhex
...
./uifl_1km/benz
...
Each file is named according to the following:
v720ut3_uifl_4km_1km_rtracv3_*_{gridname}_{species}_ppb_apr_oct_{percentile}.tif
- gridname is
grd01 or grd02 specifying the modeling domain, uifl_4km or uifl_1km, respectively
- species can be
antl (Acetonitrile),
be13 (1,3-Butadiene),
benz (Benzene),
etbz (Ethylbenzene),
etox (Ethylene Oxide),
nhex (Hexane),
strn (Styrene),
tolu (Toluene) or
xyln (mixed isomers of Xylenes).
- percentile has the format of
pXX where XX is percentile, e.g. p50 represents the 50th percentile
