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_12may.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
20120501	2667	26.96	33.72	6.76	8.81	10.86	25.09	32.68	18.44	28.69	0.548
20120502	2662	26.49	31.9	5.41	7.78	9.41	20.42	29.38	19.62	31.35	0.602
20120503	2643	23.83	28.07	4.24	7.02	8.43	17.79	29.46	16.75	34.27	0.703
20120504	2675	24.48	29.13	4.65	8.14	9.97	19.01	33.25	24.61	39.02	0.625
20120505	2609	25.29	30.4	5.11	9.09	10.67	20.19	35.95	23.13	39.36	0.513
20120506	2619	27.39	30.05	2.66	7.71	9.53	9.73	28.17	12.39	30.71	0.581
20120507	2595	25.63	30.22	4.59	8.94	10.97	17.92	34.9	25.49	43.46	0.66
20120508	2618	35.29	36.68	1.39	13.31	16.65	3.94	37.72	2.28	41.49	0.06
20120509	2621	35.57	40.25	4.67	9.78	11.85	13.13	27.49	17.13	31.43	0.587
20120510	2615	41.63	44.38	2.75	9.52	12.45	6.61	22.87	9.78	30.13	0.538
20120511	2560	43.81	43.45	-0.36	9.85	12.34	-0.81	22.47	-0.1	24.95	0.202
20120512	2442	39.28	39.41	0.13	8.97	11.5	0.33	22.84	-0.04	26.35	0.372
20120513	2577	37.49	40.61	3.12	7.97	10.11	8.32	21.26	12.38	26.33	0.634
20120514	2542	38.55	43.16	4.61	10.25	13.43	11.96	26.59	26.4	44.04	0.703
20120515	2540	36.68	44.19	7.51	12.69	15.97	20.47	34.6	23.79	40.26	0.39
20120516	2574	42.79	44.47	1.68	10.36	13.56	3.93	24.21	10.57	32.91	0.607
20120517	2586	47.07	46.72	-0.36	11.8	15.07	-0.76	25.06	12.7	40.27	0.638
20120518	2600	48.29	48.94	0.65	11.1	14.65	1.35	22.99	7.71	32.5	0.48
20120519	2514	47.84	51.03	3.19	9.58	13.27	6.66	20.02	9.23	25.47	0.454
20120520	2587	43.61	48.63	5.02	10.23	13.56	11.51	23.45	14.17	28.15	0.403
20120521	2573	43.67	44.88	1.21	9.93	12.89	2.77	22.74	9.25	31.08	0.634
20120522	2586	46.41	41.99	-4.43	8.44	11.16	-9.54	18.18	-10.16	24.47	0.679
20120523	2588	38.5	39.63	1.14	7.57	9.6	2.95	19.68	1.31	21.83	0.451
20120524	2582	35.13	39.56	4.43	7.78	9.32	12.63	22.16	10.23	21.67	0.396
20120525	2584	29.19	35.78	6.59	9.49	11.35	22.58	32.52	19.57	30.45	0.305
20120526	2529	29.94	37.44	7.51	9.76	11.35	25.08	32.59	22.22	30.64	0.418
20120527	2573	29.11	35.25	6.13	9.02	10.59	21.07	30.99	18.92	30.45	0.407
20120528	2567	26.57	33.62	7.05	9.33	11.15	26.54	35.11	24.85	34.7	0.526
20120529	2552	24.98	31.67	6.69	8.99	10.67	26.8	35.98	28.67	38.39	0.654
20120530	2561	27.12	33.79	6.67	12.46	14.81	24.6	45.95	30.03	47.23	0.441
20120531	2564	29.6	37.24	7.64	14.44	17.12	25.79	48.78	31.17	50.66	0.317
all days	80105	34.73	38.54	3.81	9.67	12.27	10.98	27.85	15.26	33.32	0.566

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