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 2006 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)
camx620_cb6r2.tx.bc06_06jun.r3d.2006_5layer_YSU_WSM6_3dsfc1h_fddats_gq_sfc_0.tx_4km

All Data
Episode Date	Valid Data	Mo ppb	Mm ppb	MB ppb	ME ppb	RMSE ppb	NMB %	NME%	FB %	FE %	R²
20060531	2526	26.02	38.89	12.88	15.95	19.73	49.5	61.29	39.75	59.74	0.353
20060601	2519	27.05	47.07	20.01	21.55	25.09	73.99	79.67	58.27	71.64	0.39
20060602	2537	36.21	47.8	11.59	17.98	22.58	32.01	49.66	42.22	65.41	0.463
20060603	2508	43.24	57.13	13.89	15.96	19.31	32.13	36.91	35.86	45.69	0.737
20060604	2547	46.31	58.51	12.2	15.06	19.37	26.34	32.53	30.35	36.92	0.626
20060605	2493	45.6	55.97	10.37	12.96	15.9	22.75	28.41	27.12	34.17	0.767
20060606	2462	48.76	57.46	8.69	12.51	16.3	17.83	25.64	22.36	32.27	0.673
20060607	2506	46.23	57.44	11.21	13.71	17.23	24.24	29.66	25.53	31.98	0.609
20060608	2516	48.88	61.69	12.81	15.7	19.31	26.21	32.12	31.4	38.49	0.704
20060609	2532	50.87	64.57	13.7	17.56	22.11	26.93	34.51	31.06	39.49	0.604
20060610	2457	51.48	66.19	14.72	16.73	20.87	28.59	32.51	30.88	34.56	0.565
20060611	2544	44.23	57.05	12.82	14.33	19.3	28.98	32.39	30.69	34.05	0.392
20060612	2532	40.39	54.45	14.06	16.81	21.33	34.81	41.63	41.74	50.29	0.681
20060613	2528	42.7	58.83	16.13	18.02	22.58	37.78	42.19	45.26	52.56	0.67
20060614	2509	58.01	61.91	3.9	9.88	13.18	6.72	17.03	9.62	21.72	0.706
20060615	2545	50.58	62.86	12.28	14.61	18.54	24.29	28.88	28.19	33.25	0.566
20060616	2600	23.89	31.57	7.68	8.37	10.25	32.14	35.05	27.67	31.98	0.683
20060617	2470	22.91	27.99	5.08	11.3	13.19	22.17	49.31	32.73	49.3	0.343
20060618	2587	30.99	28.44	-2.55	14.29	17.69	-8.24	46.12	4.98	52.55	0.371
20060619	2574	27.01	28.01	1.01	9.31	11.31	3.73	34.46	2.93	49.89	0.584
20060620	2619	19.68	28.59	8.9	10.83	13.42	45.24	55.03	37.83	51.77	0.343
20060621	2639	17.22	34.26	17.04	17.2	19.44	98.99	99.89	72.31	73.86	0.449
20060622	2642	19.06	32.01	12.94	13.56	15.43	67.88	71.15	57.44	62.97	0.581
20060623	2640	24.48	40.72	16.24	17.4	21.1	66.36	71.11	58.79	66.99	0.648
20060624	2569	29.17	48.2	19.03	20.39	23.39	65.24	69.9	60.15	68.37	0.63
20060625	2664	36.42	52.55	16.13	17.69	21.57	44.28	48.56	50.18	56.55	0.576
20060626	2644	44.86	51.4	6.53	12.63	16.71	14.57	28.15	18.09	34.45	0.408
20060627	2642	47.34	51.53	4.19	10.17	14.09	8.85	21.48	12.37	29.32	0.63
20060628	2651	49.41	58.2	8.79	14.69	19.67	17.79	29.72	26.75	44.32	0.594
20060629	2716	53.01	62.33	9.32	14.29	19.28	17.58	26.95	26.68	40.51	0.662
20060630	2704	46.72	65.12	18.4	21.06	25.58	39.38	45.07	41.45	48.93	0.515
20060701	2601	31.27	55.8	24.54	25.87	29.63	78.48	82.75	61.69	69.16	0.392
20060702	2664	23.38	54.25	30.88	31.32	33.84	132.1	133.98	84.81	86.8	0.328
all days	84887	37.91	50.22	12.31	15.77	19.98	32.48	41.61	36.71	48.62	0.608

select an episode
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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