Texas Air Quality Modeling Results: Ozone Performance Statistics

Interactive chart, map, and data table of daily and monthly ozone (O3) performance statistics by ozone area and monitoring site, comparing the results of the TCEQ’s air quality modeling with surface observations.

Evaluating model performance determines how well it replicates an historical episode. Performance statistics do not feed directly into future ozone estimates or regulatory decisions.

To compare results of ozone photochemical modeling to actual observed data from surface monitoring sites, TCEQ calculates the following statistical metrics, recommended by the EPA (Modeling Guidance for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze ).

Mo - Mean of Observed Values
Mm - Mean of Modeled Values (ideal if Mm = Mo)
MB - Mean Bias (mean difference; ideal value = 0)
ME - Mean Error (mean absolute difference; ideal value = 0)
RMSE - Root Mean Squared Error (ideal value = 0)
NMB - Normalized Mean Bias (relative mean difference; ideal value = 0)
NME - Normalized Mean Error (relative mean absolute difference; ideal value = 0)
FB - Fractional Bias (value range: -200% to 200%; ideal value = 0)
FE - Fractional Error (value range: 0 to 200%; ideal value = 0)
R² - Coefficient of Determination (square of correlation coefficient; value range: 0 to 1; ideal value = 1)

Daily Statistics by Area
Monthly Statistics by Site

An interactive map and data table of ozone performance statistics of the TCEQ's 2019 photochemical modeling. Base case model results are compared with surface observations by episode at individual monitoring sites in the 4×4km-cell modeling domain (txs_4km).

If you have any questions regarding this interactive map, please send an email to amda@tceq.texas.gov with the subject "2019 Texas Photochemical Modeling Results - Monthly Model Performance Statistics by Monitoring Site".

Model Episode

Model Run

Data Type

Statistic Metric

Spatial Option

Temporal Option

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Data Range:
min max

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model run name

Show sites in area


Area	EPA Site Code	CAMS Site Code	Model Site Code	Valid Data	Mo ppb	Mm ppb	MB ppb	ME ppb	RMSE ppb	NMB %	NME %	FB %	FE %	R²

select an episode
(loads new page)

select a model run

choose a data type

choose a statistic type

choose 2×2-cell bi-linear interpolated or cell value

choose hourly or eight-hour value

change marker size
change data range for marker colors
show/hide data value label on markers
show/hide map legend

display table data from sites of a selected area

export table data to a CSV file

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