Texas Photochemical Modeling Results—Model Performance Statistics by Area and Day

Interactive bar chart and data table of model performance statistics comparing the results of the TCEQ’s air quality modeling with surface observations.

The purpose of evaluating model performance is to determine how well the model 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, the 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)

Statistics by area and day
Statistics by episode and site

This page shows interactive chart and data table of ozone performance statistics by days for a selected area from the 2012 photochemical modeling.

The statistical performance of the TCEQ's base case ozone modeling is comparable to and, in many cases, above average of other ozone modeling efforts discussed in a research paper Compilation and Interpretation of Photochemical Model Performance Statistics Published between 2006 and 2012 (Simon, et al, Atmospheric Environment 61:124–139, November 2012).

The median value, Interquartile Range (IQR) , and value range of ozone statistics presented in this paper (Fig. 4) are available to overlay on the chart for MB, ME, RMSE, NMB, NME, and R² of hourly, daily maximum of hourly, and daily maximum of eight-hour data.

If you have any questions regarding this interactive chart, please send an email to amda@tceq.texas.gov with the subject "Texas Photochemical Modeling Results - Model Performance Statistics by Area and Day".

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Model Performance Statistics of Hourly O3 Concentrations in tx_4km Domain. Mean Modeled (Mm) and Mean Observered (Mo) of All Data (cell values)

Long description.

No description available.

Structure.

Chart type: Combination chart.

The chart has 2 X axes displaying values and navigator-x-axis.

The chart has 2 Y axes displaying Mean Concentration (ppb) and navigator-y-axis.

View as data table.

Chart graphic.

Model Performance Statistics of Hourly O3 Concentrations in tx_4km Domain (cell values)
camx650_cb6r4h.tx.bc12_12sep.r6f2_r4f.2012_wrf371_p2ma_i2mSNgqsfc0_h.tx_4km

All Data
Episode Date	Valid Data	Mo ppb	Mm ppb	MB ppb	ME ppb	RMSE ppb	NMB %	NME%	FB %	FE %	R²
20120901	2438	20.88	25.55	4.67	6.94	8.66	22.39	33.26	24.04	36.2	0.667
20120902	2564	19.81	23.32	3.5	6.4	7.71	17.68	32.31	19.93	38.63	0.635
20120903	2559	20.05	24.24	4.19	6.55	7.82	20.89	32.68	22.2	38.19	0.699
20120904	2523	20.8	24.48	3.68	6.82	8.36	17.7	32.78	21.19	40.8	0.71
20120905	2526	19.74	23.88	4.14	7.11	8.69	21	36.04	26.86	45.56	0.734
20120906	2512	23.38	29.15	5.77	10.13	13.72	24.67	43.32	32.15	55.24	0.657
20120907	2561	24.12	33.3	9.18	11.45	14.66	38.08	47.47	43.59	55.18	0.717
20120908	2541	31.45	36.36	4.92	9.12	11.2	15.63	29.01	24.14	36.68	0.644
20120909	2613	35.21	38.46	3.25	8.46	10.9	9.24	24.02	18.27	33.15	0.638
20120910	2599	38.51	41.4	2.89	10.86	13.91	7.51	28.2	25.94	45.46	0.671
20120911	2623	43.27	45.27	2	11.93	15.28	4.62	27.56	12.28	39.17	0.437
20120912	2619	28.93	30.96	2.03	7.88	9.77	7.01	27.22	6.09	33.63	0.651
20120913	2598	19.63	27.87	8.24	10.93	13.85	41.95	55.67	36.54	51.14	0.293
20120914	2592	21.92	33.41	11.49	12.8	14.94	52.39	58.41	41.97	52.03	0.537
20120915	2546	28.34	39.08	10.75	11.99	14.08	37.92	42.3	33.82	41.16	0.664
20120916	2607	27.88	36.58	8.7	10.56	12.9	31.2	37.89	32.3	40.48	0.644
20120917	2619	27.78	40.06	12.28	12.98	15.29	44.19	46.71	41.3	44.36	0.588
20120918	2637	27.01	34.55	7.54	11.38	13.83	27.92	42.13	41.46	55.42	0.565
20120919	2624	33.34	34.51	1.17	7.69	9.87	3.52	23.08	11	33.18	0.708
20120920	2619	37.51	35.93	-1.57	10.5	13.46	-4.2	28.01	11.24	45.23	0.657
20120921	2655	38.75	39.19	0.44	12.1	15.03	1.14	31.24	17.76	49.44	0.575
20120922	2587	34.34	40.06	5.72	12.59	15.73	16.66	36.67	30.85	50.9	0.537
20120923	2657	32.96	39.36	6.4	10.88	13.49	19.43	32.99	33.54	48.43	0.687
20120924	2643	37.47	40.12	2.64	11.03	14.11	7.06	29.43	19.95	44.48	0.571
20120925	2613	41.42	41.13	-0.28	8.22	10.73	-0.69	19.86	0.35	24.72	0.404
20120926	2645	39.47	36.33	-3.14	7.79	10.47	-7.96	19.75	-9.49	26.58	0.473
20120927	2641	30.66	33.49	2.83	9.22	11.43	9.23	30.08	13.58	39.23	0.523
20120928	2620	20.71	29.97	9.25	11.91	14.35	44.68	57.51	46.04	60.62	0.521
20120929	2520	18.02	21.05	3.03	5.99	7.59	16.82	33.24	13.1	38.32	0.538
20120930	2674	29.18	32.59	3.41	6.28	7.87	11.68	21.52	9.63	22.49	0.596
all days	77775	29.18	33.8	4.62	9.63	12.3	15.84	33.01	23.33	42.19	0.614

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

choose ozone area

click a legend item to toggle the display of corresponding data series on the chart

click here to save chart image or data series

hold the left mouse button and select a rectangle in the chart area to zoom in

hover the cursor over chart to show the data values of a particular day

move the cursor into this label area, hold the left mouse button and move up or down to change the upper value; double-click to reset to a default value

similarly, change the bottom value here; the bottom value cannot be changed below zero

change date range by sliding the left and/or right handles on this navigation bar